The Genetics of Behavior

Hierarchy Control Maritime

To say that behavior is inherited does not mean that specific genes code for specific behaviors. Genes code for proteins, and there are many complex steps between the expression of a gene as a protein product and the expression of a behavior. In no case are all the steps between a gene and its influence on a behavior known. Nevertheless, it is clear that behavior has genetic determinants. In this section we will look at three approaches to investigating how genes affect behavior hybridization,...

Does Plasma Membrane Glow When Current Is Supplied

Host E. coli are screened to detect the presence of recombinant DNA. 1 A plasmid has genes for resistance to both ampicillin (ampr) and tetracycline (tetr). Foreign DNA is inserted at the BamHI recognition site, which is within the tetr gene. Foreign DNA is inserted at the BamHI recognition site, which is within the tetr gene. The resulting recombinant DNA has an intact functional gene for ampicillin resistance but not for tetracycline resistance. pBR322 recombinant Resistant plasmid Phenotype...

The Regulation of Food Intake

Obesity is a major health issue in the United States. People spend billions of dollars every year on schemes to lose weight, but the problem still increases. A simple rule take in fewer calories than your body burns, but maintain a balanced diet should solve the problem, but it doesn't. Why As we noted at the beginning of this chapter, social and lifestyle factors play a major role in obesity, but these factors play out against a genetic and regulatory background. 50.20 Fuel Molecule Traffic...

Some cancers are caused by viruses

Peyton Rous's discovery in 1910 that a sarcoma in chickens is caused by a virus that is transmitted from one bird to another spawned an intensive search for cancer-causing viruses in humans. At least five types of human cancer are probably caused by viruses (Table 17.1). Hepatitis B, a liver disease that affects people all over the world, is caused by the hepatitis B virus, which contaminates blood or is carried from mother to child during birth. The viral infection can be long-lasting and may...

Ggacacctc Cctgtggag

Membrane Cancer Cells

AS AS AA AS Genotypes of family members deduced from allele-specific hybridization AS AS AA AS Genotypes of family members deduced from allele-specific hybridization 17.13 A Cancer Cell with Its Normal Neighbors This small-cell lung cancer cell yellow green is quite different from the surrounding lung epithelial cells from which it came. This particular form of cancer is very lethal, with a 5-year survival rate of less than 10 percent. Most cases are caused by smoking. 17.13 A Cancer Cell with...

Info

Primary Transcript Rna

12 18 24 Number of weeks after conception 18 24 30 36 Number of weeks after birth 12 18 24 Number of weeks after conception 18 24 30 36 Number of weeks after birth The vertical dimension of these shapes represents the relative expression of the globin genes in different tissues. As we saw in the previous section, eukaryotic protein-coding genes contain some sequences that do not appear in the mature mRNA that is translated into proteins. To produce the mature mRNA, the primary transcript...

Sources of energy can be stored in the body

Steps Starvation

Although the cells of the body use energy continuously, most animals do not eat continuously. Therefore, animals must store fuel molecules that can be released as needed between meals. Carbohydrates are stored in liver and muscle cells as glyco-gen, but the total glycogen store represents only about a day's basal energy requirements 1,500-2,000 Cal . Fat is the most important form of stored energy in the bodies of animals. Not only does fat have more energy per gram than glycogen, but it can be...

Fertilizers and lime are used in agriculture

Agricultural soils often require fertilizers because irrigation and rainwater leach mineral nutrients from the soil and because the harvesting of crops removes the nutrients that the plants took up from the soil during their growth. Crop yields decrease if any essential element is depleted. Mineral nutrients may be replaced by organic fertilizers, such as rotted manure, or by inorganic fertilizers of various types. organic and inorganic fertilizers. The three elements most commonly added to...

Cancer cells differ from their normal counterparts

Cancer cells differ from the normal cells from which they originate in two major ways. CANCER CELLS LOSE CONTROL OVER CELL DIVISION. Most cells in the body divide only if they are exposed to extracellular influences, such as growth factors or hormones. Cancer cells do not respond to these controls, and instead divide more or less continuously, ultimately forming tumors large masses of cells . By the time a physician can feel a tumor or see one on an X ray or CAT scan, it already contains...

Decreasing heat loss is important for life in the cold

The coldest habitats on Earth are in the Arctic, the Antarctic, and at the peaks of high mountains. Many birds and mammals, but almost no reptiles or amphibians, live in these places. What adaptations besides endothermy characterize species that live in the cold The most important adaptations of endotherms to cold environments are those that reduce heat loss to the environment. Since most heat is lost from the body surface, many cold-climate species have a smaller surface area than their...

T Cells The Cellular Immune Response

Cell Helper Immune Response

Thus far we have been concerned primarily with the humoral immune response, whose effector molecules are the antibodies secreted by plasma cells that develop from activated B cells. T cells, as we have seen, are involved in the humoral immune response, but they are also the effectors of the cellular immune response, which is directed against any factor, such as a virus or mutation, that changes a normal cell into an abnormal cell. In this section, we will describe two types of effector T cells...

Interpretation

Movement Cortex Human

This model would explain the results of cell-to-cell connections. Relay cells Simple cells Complex cells Retinal ganglion cells in thalamus in cortex in cortex Conclusion Cells in the retina, thalamus, and cortex are connected in such a way as to respond to specific patterns of light. Relay cells Simple cells Complex cells Retinal ganglion cells in thalamus in cortex in cortex Conclusion Cells in the retina, thalamus, and cortex are connected in such a way as to respond to specific patterns of...

Most species produce more than one nitrogenous waste

Humans are ureotelic, yet we also excrete uric acid and ammonia. The uric acid in human urine comes largely from the metabolism of nucleic acids and caffeine. In the condition known as gout, uric acid levels in the tissue fluid increase, and uric acid precipitates out of solution in the joints and elsewhere, causing swelling and pain. The excretion of ammonia is an important mechanism for regulating the pH of the tissue fluid. In some species, different developmental stages live in different...

Fungal Associations

Glomus Caledonium

Earlier in this chapter we mentioned mycorrhizae and lichens, two kinds of symbiotic, mutualistic associations between fungi and other organisms. Now that we have learned a bit about fungal diversity, let's consider mycorrhizae and lichens in greater detail. Mycorrhizae are essential to many plants Almost all tracheophytes require a symbiotic association with fungi. Unassisted, the root hairs of such plants do not absorb enough water or minerals to sustain growth. However, their roots usually...

The Phosphorus Cycle

Phosphorus Mine Image

Phosphorus accounts for only about 0.1 percent of Earth's crust, but it is an essential nutrient for all life forms. It is a key component of DNA and ATP. Unlike the other elements discussed in this section, phosphorus lacks a gaseous phase. Some phosphorus is transported on dust particles, but in general the atmospheric compartment plays a very minor role in the phosphorus cycle. The global phosphorus cycle takes millions of years to complete because the processes of rock formation on the...

The adrenal gland is two glands in one

Amine Hormone Adrenal Medulla

An adrenal gland sits above each kidney, just below the middle of your back. Functionally and anatomically, each adrenal gland consists of a gland within a gland Figure 42.10 . The core, called the adrenal medulla, produces the hormone epinephrine also known as adrenaline and, to a lesser degree, norepinephrine or noradrenaline , which also acts as a neurotransmitter in the nervous system . Surrounding the medulla is the adrenal cortex, which produces other hormones. The medulla develops from...

Basal metabolic rates of endotherms are related to body size

Obviously, the total basal metabolic rate of an elephant is greater than that of a mouse. After all, the elephant is more than 100,000 times more massive than the mouse. However, the metabolic rate of the elephant is only about 7,000 times greater than that of the mouse. That means that the metabolism of a gram of mouse tissue is much greater than the metabolism of a gram of elephant tissue more than 20 times greater Figure 41.13 . Across all of the endotherms, basal metabolic rate per gram of...

Skeletal Systems

Leg Muscles Joints Tendons Kick Ball

To create significant movement, they must have something to pull on. In some cases, muscles pull on each other consider the trunk of the elephant or the arms of an octopus. In most cases, however, skeletal systems provide rigid supports against which muscles can pull, creating directed movements. In this section, we'll examine the three types of skeletal systems found in animals hydrostatic skeletons, exoskeletons, and endoskeletons. A hydrostatic skeleton...

Chylomicrons Are Like The Tiny Micelles Of Dietary Fat In The Lumen Of The Small Intestine In That Both

Most of the metabolic energy that a bird requires for a longdistance migratory flight is stored as 2. Which statement about essential amino acids is true a. They are not found in vegetarian diets. b. They are stored by the body for the times when they are needed. c. Without them, one is undernourished. d. All animals require the same ones. e. Humans can acquire all of theirs by eating milk, eggs, and meat. 3. Which statement about vitamins is true a. They are essential inorganic nutrients....

Sickle Cell Anemia Mutation

Missense Mutation Sickle Cell Anemia

J Cleaving the polypeptide allows the fragments to fold into different shapes. Adding sugars is important for targeting and recognition. Added phosphate groups alter the shape of the protein. most polypeptides are modified after translation, and these modifications are essential to the final functioning of the protein Figure 12.16 . Proteolysis is the cutting of a polypeptide chain. Cleavage of the signal sequence from the growing polypeptide chain in the ER is an example of proteolysis the...

Four features characterize the immune system

Plasma Membrane Features

The characteristic features of the immune system are specificity, the ability to respond to an enormous diversity of foreign molecules and organisms, the ability to distinguish self from nonself, and immunological memory. I A fragment of a bacterium binds to the receptor CD14. I A fragment of a bacterium binds to the receptor CD14. The transcription factor, NF-kB is phosphorylated. The transcription factor, NF-kB is phosphorylated. 18.5 Cell Signaling and Defense Binding of a molecule from a...

Carnivorous and Heterotrophic Plants

Heterotrophic Plants

Some plants that are found primarily in nitrogen-deficient soils augment their nitrogen and phosphorus supply by capturing and digesting flies and other insects. There are about 450 of these carnivorous species, the best-known of which are Venus flytraps genus Dionaea Figure 37.9a , sundews genus Drosera Figure 37.9b , and pitcher plants genus Sarracenia . Carnivorous plants are normally found in boggy regions where the soil is acidic. Most decomposing organisms require a less acidic pH to...

Disorders of the Immune System

Sometimes the immune system fails us in one way or another. It may overreact, as in an allergic reaction it may attack self antigens, as in an autoimmune disease or it may function weakly or not at all, as in an immune deficiency disease. After a look at allergies and autoimmune diseases, we will examine the acquired immune deficiency that characterizes AIDS. hypersensitivity. A common type of condition arises when the human immune system overreacts to is hypersensitive to a dose of antigen....

Plasma Membrane

Animal Critical Temperatures

Lower Upper critical critical temperature temperature Below the lower critical temperature, the animal produces metabolic heat to compensate for increased heat loss to the environment. Above the upper critical temperature, the animal must expend energy to lose heat by panting or sweating, which makes its metabolic rate increase. Below the lower critical temperature, the animal produces metabolic heat to compensate for increased heat loss to the environment. Above the upper critical temperature,...

The Role of Differential Gene Expression in Establishing Body Segmentation

Drosophila Maternal Gene Nanos Bicoid

Insects such as the fruit fly Drosophila melanogaster develop a highly modular body composed of different types of segments. Complex interactions of different sets of genes underlie the pattern formation of segmented bodies. Unlike the body segments of segmented worms such as earthworms, which are all essentially alike, the segments of the Drosophila body are clearly different from one another. The adult fly has an anterior head composed of several fused segments , three different thoracic...

Hormones can be divided into three chemical groups

There is enormous diversity in the chemical structure of hormones, but most of them can be divided into three groups Peptides or proteins e.g., insulin Steroid hormones derivatives of the steroid cholesterol e.g., testosterone Amines derivatives of the amino acid tyrosine e.g., thyroxine Most hormones are peptides or proteins. They are water-soluble and therefore easily transported in the blood, but they cannot easily pass through lipid-rich cell membranes. Therefore, peptide and protein...

Ulothrix Life Cycle

Ulothrix Life Cycle

The zygote is the only diploid cell in the haplontic life cycle. 28.27 A Haplontic Life Cycle In the life cycle of Ulothrix, a filamentous, multicellular haploid gametophyte generation alternates with a diploid sporophyte generation consisting of a single cell the zygote . Like Ulva gametophytes, Ulothrix gametophytes can also reproduce asexually left side of figure . The zygote is the only diploid cell in the haplontic life cycle.

Nffi Fertilization is the union of sperm and egg

Slow Block Polyspermy

f The union of the haploid sperm and the haploid egg 1 f creates a single diploid cell, called a zygote, which will develop into an embryo. Fertilization does more, however, than just restore the full genetic complement of the animal. The events and processes associated with fertilization help eggs and sperm get together, prevent the union of sperm and eggs of different species, guarantee that only one sperm will enter an egg, and activate the egg metabolically. Fertilization involves a...

Glucagon Release

Glucagon Release

b Fuel traffic during the postabsorptive period b Fuel traffic during the postabsorptive period glucagon is released if blood glucose falls too low glucagon is released if blood glucose falls too low Triglycerides and fatty acids Glucose and glycogen Proteins and amino acids 50.21 A Single-Gene Mutation Leads to Obesity in Mice Leptin serves as a negative feedback signal to the brain to limit food intake. The fat cells of the ob ob mouse on the left do not produce leptin. The wild-type mouse...

Glial cells are also important components of nervous systems

Schwann Cell

Neurons are not the only type of cell in the nervous system. In fact, there are more glial cells than neurons in the human brain. Like neurons, glial cells come in several forms and have a diversity of functions. Some glial cells physically support and orient the neurons and help them make the right contacts during embryonic development. Other glial cells insulate axons. In the peripheral nervous system, Schwann cells wrap around the axons of neurons, covering them with concentric layers of...

[V h The Mammalian Excretory System

Capillary Adrenal Gland

' The adaptations of mammals and birds that allowed them to produce urine hyperosmotic to their tissue fluid were an important step in vertebrate evolution. These adaptations enabled the excretory system to conserve water while still excreting excess salts and nitrogenous wastes. Mammals and birds have high body temperatures and high metabolic rates, and therefore have the potential for a high rate of water loss. Being able to minimize water loss from their excretory systems made it possible...

General Biology of the Prokaryotes

Bacteria With Flagella

There are many, many prokaryotes around us everywhere. Although most are so small that we cannot see them with the naked eye, the prokaryotes are the most successful of all creatures on Earth, if success is measured by numbers of individuals. The bacteria in one person's intestinal tract, for example, outnumber all the humans who have ever lived, and even the total number of human cells in their host's body. Some of these bacteria form a thick lining along the intestinal wall. Bacteria and...

Blood flows from right heart to lungs to left heart to body

Heart Pressure Left Right Ventricle

Let's follow the circulation of the blood through the heart, starting in the right heart. The right atrium receives deoxy-genated blood from the superior upper vena cava and the inferior lower vena cava see Figure 49.3 , large veins that collect blood from the upper and lower body, respectively. contract, the atrioventricular valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 3 Blood is pumped out of the ventricles and into the aorta and pulmonary...

Which Biome Is Dominated By Low-growing Shrubs And Trees That Have Tough Evergreen Leaves

Thorny Trees Madagascar

Low stature shrubs and herbaceous plants Plants Extremely high in South Africa and Australia Animals Rich in rodents and reptiles very rich in insects, especially bees Fynbos vegetation, Cape of Good Hope, South Africa Fynbos vegetation, Cape of Good Hope, South Africa The chaparral climate is dry and pleasant The chaparral biome is found on the west sides of continents at moderate latitudes around 30o , where cool ocean waters flow offshore. Winters in this biome are cool and wet summers are...

Most chemical digestion occurs in the small intestine

Liver And Bile Secretion

In the small intestine, the digestion of carbohydrates and proteins continues, and the digestion of fats and the absorption of nutrients begin. The small intestine takes its name from its diameter it is in fact very large organ, about 3 meters long in an adult. Because of its length, and because of the folds, villi, and microvilli of its lining, its inner surface area is enormous about 550 m2, or roughly the size of a tennis court. Across this surface, the small intestine absorbs all the...

Start

Conjugation Paramecium

After a mosquito ingests blood, male and female gametocytes develop into gametes, which fuse. The resulting zygote, the only diploid stage in the life cycle, enters the mosquito's gut wall and forms a cyst. After a mosquito ingests blood, male and female gametocytes develop into gametes, which fuse. The resulting zygote, the only diploid stage in the life cycle, enters the mosquito's gut wall and forms a cyst. 3 Within the cyst, the zygote gives rise to sporozoites. 5 The mosquito injects...

Reproductive technologies help solve problems of infertility

There are many reasons why a man and woman may not be able to have children. The man's rate of sperm production may be low, or his sperm may lack motility. The mucus in the woman's reproductive tract may be thick and not conducive to sperm reaching the oviducts. Structural problems may also exist, such as blockage of the oviducts by scar tissue or by endometriosis, a proliferation of endometrial cells outside of the uterus. In some cases, treatment with powerful chemicals to cure cancer damages...

Nuclear Transplantation

Nuclear Transplantation Sheep

Question Are differentiated animal cells totipotent An egg is removed from a Scottish blackface ewe. Question Are differentiated animal cells totipotent An egg is removed from a Scottish blackface ewe. 8 The embryo develops and Dolly is born. Dorset sheep, genetically identical to 1 Conclusion Differentiated animal cells are totipotent in nuclear transplant experiments. 8 The embryo develops and Dolly is born. Dorset sheep, genetically identical to 1 Conclusion Differentiated animal cells are...

The Nitrogen Cycle

Mississippi River Dead Zones

Nitrogen gas N2 makes up 78 percent of the atmosphere, but most organisms cannot use nitrogen in its gaseous form. Only a few species of microorganisms can convert atmospheric N2 into forms that are usable by plants, a process called nitrogen fixation. Denitrification, the principal process that removes nitrogen from the biosphere and returns it to the atmosphere, is also carried out by microorganisms. These movements of nitrogen among organisms and between organisms and the atmosphere were...

Speciation Is An Important Component Of Evolution Because It

A. actually interbreeding natural populations that are reproductively isolated from other such groups. b. potentially interbreeding natural populations that are reproductively isolated from other such groups. c. actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. d. actually or potentially interbreeding natural populations that are reproductively connected to other such groups. e. actually interbreeding natural populations that are...

Spraying Dwarf Plants With Gibberelin

Plants Without Gibberellins

Gibberellin Aj important in stem growth Gibberellin A3 commercially available In 1809, the study of the gibberellins began indirectly with observations of the bakanae, or foolish seedling, disease of rice. Seedlings affected by this disease grow tall more rapidly than their healthy neighbors, but this rapid growth gives rise to spindly plants that die before producing seeds the rice grains used for food . The disease has had considerable economic impacts in several parts of the world. It is...

Distal Convoluted Tubule Function

Medullary Venule

Urine leaves the kidney from the inner surface of the medulla and is collected in the ureter. Urine leaves the kidney from the inner surface of the medulla and is collected in the ureter. fytyi 51.9 The Human Excretory System a The human kidneys If fi are positioned in the upper dorsal region of the abdominal V j cavity, ft The human kidney has a regular internal tissue ' structure that is the basis for its function, c The glomeruli and the proximal and distal convoluted tubules are located in...

Light Absorption Optic Nerve

Retina Inverted

A bright light stimulus results in a strong hyperpolarization. opsin pass through several unstable intermediate stages. One of these stages is known as photoexcited rhodopsin because it triggers a cascade of reactions that result in the alteration of membrane potential that is the photoreceptor cell's response to light. To get a better idea of how rhodopsin alters the membrane potential of a photoreceptor cell and how that photoreceptor cell signals that it has been stimulated by light, let's...

Self Quiz

Which of the following describes the route of sensory information from the foot to the brain a. Ventral horn, spinal cord, medulla, cerebellum, midbrain, thalamus, parietal cortex b. Dorsal horn, spinal cord, medulla, pons, midbrain, hypothalamus, frontal cortex c. Dorsal horn, spinal cord, medulla, pons, midbrain, thalamus, parietal cortex d. Ventral horn, spinal cord, pons, cerebellum, midbrain, thalamus, parietal cortex e. Dorsal horn, spinal cord, medulla, pons, midbrain, thalamus,...

Tissues Organs and Organ Systems

Four Types Tissue

Cells are the basic building blocks of multicellular animals. When cells with the same characteristics or specializations are grouped together, they form a tissue. There are four basic types of tissues epithelial, connective, muscle, and nervous but there are variations on each basic type. An organ is usually made up of several different tissue types Figure 41.2 . 41.2 Four Types of Tissue All cells can be classified into one of four tissue types. An organ such as the stomach is made up of...

Environments and animals can be classified in terms of salts and water

Salt Gland Marine Birds

The salt concentration, or osmolarity, of ocean water is about 1,070 milliosmoles liter mosm l , and fresh water is generally between 1 and 10 mosm l. Aquatic environments grade continuously from fresh to extremely salty. Consider a place where a river enters the sea through a bay or a marsh. Aquatic environments within that bay or marsh range in os-molarity from that of the fresh water of the river to that of the open sea. Evaporating tide pools can reach an even greater osmolarity than...

Uh Endocytosis and Exocytosis

Concentration Outside Cell

1 f Macromolecules such as proteins, polysaccharides, and nucleic acids are simply too large and too charged or polar to pass through membranes. This is a fortunate property. Think of the consequences if these molecules could diffuse out of cells A red blood cell would not retain its hemoglobin On the other hand, cells must sometimes take up or secrete intact large molecules. As we saw in Chapter 4, this can be done by means of vesicles that either pinch off from the plasma membrane and enter...

Human brains became larger

The earliest members of Homo sapiens had larger brains than members of the earlier species of Homo. Brain size in the lineage increased rapidly, reaching modern size by about 160,000 years ago. This striking change was probably favored by an increasingly complex social life. The ability of group members to communicate with one another would have been valuable in cooperative hunting and gathering and for improving one's status in the complex social interactions that must have characterized early...

Flowering plants have microscopic gametophytes

Tube Cell Nucleus

Before reading this section, you may wish to review the section in Chapter 29 entitled Life cycles of plants feature alternation of generations pages 571-572 . Central to understanding plant reproduction is the concept of alternation of generations, in which a multicellular diploid generation alternates with a multicellular haploid generation. In angiosperms, the diploid sporophyte generation is the larger and more conspicuous one. The sporophyte generation produces flowers. The flowers produce...

. Negative Feedback A. Is Not As Common As Positive Feedback In Regulatory Systems Of The Body. B. Is A Feature Of

If the Q10 of the metabolic rate of an animal is 2, then a. the animal is better acclimatized to a cold environment than if its Q10 is 3. c. the animal consumes half as much oxygen per hour at 20 C as it does at 30 C. d. the animal's metabolic rate is not at basal levels. e. the animal produces twice as much heat at 20 C as it does at 30 C. 2. Which statement about brown fat is true a. It produces heat without producing ATP. b. It insulates animals acclimatized to cold. c. It is a major...

Birds Make Extremely Efficient Use Of Air. This System Enables Them To Fly Even At An Altitude Of 8 000 Meters Where

Respiratory Diffusion

And so back up the gradual slopes, the wind behind me. A much greater effort this, stopping every few yards with a slight anxiety lest I should not make the distance. As I approached the tents, I was astonished to see a bird, a chough, strutting about on the stones near me. During this day, too, Charles Evans saw what must have been a migration of small grey birds. Neither of us had thought to find any signs of life as high as this. Sir John Hunt, Ascent of Everest, 1953 In his book about the...

9. Which Statement About Enzyme Inhibitors Is Not True

Coenzymes differ from enzymes in that coenzymes are a. only active outside the cell. e. always carriers of high-energy phosphate. 2. Which statement about thermodynamics is true a. Free energy is used up in an exergonic reaction. b. Free energy cannot be used to do work, such as chemical transformations. c. The total amount of energy can change after a chemical transformation. d. Free energy can be kinetic but not potential energy e. Entropy tends always to a maximum. a. the rate depends on...

A hierarchy of meristems generates a plants body

Meristems Plants Lateral Apical

Apical meristems give rise to the primary plant body, which is the entire body of many plants. Lateral meristems give rise to the secondary plant body. The stems and roots of some plants most obviously trees form wood and become thick it is the lateral meristems that give rise to the tissues responsible for this thickening. apical meristems. Apical meristems are located at the tips of roots and stems and in buds. They extend the plant body by producing the cells that subsequently expand and...

Possession Of Which Feature Is Not Desirable In A Vector For Gene Cloning

B. cleave DNA at highly specific recognition sequences. c. are inserted into bacteria by bacteriophages. d. are made only by eukaryotic cells. e. add methyl groups to specific DNA sequences. 2. When fragments of DNA of different sizes are placed in an electrical field, a. the smaller pieces migrate most quickly to the positive pole. b. the larger pieces migrate most quickly toward the positive pole. c. the smaller pieces migrate most quickly toward the negative pole. d. the larger pieces...

Steps Of Muscle Contraction

Sarcoplasmic Reticulum Cycles

RESULTS Autonomic neurotransmitters alter membrane resting potential and thereby determine the rate that smooth muscle cells fire action potentials. Conclusion Smooth muscle contraction is stimulated by stretch and by the parasympathetic neurotransmitter acetylcholine. 47.2 Mechanisms of Smooth Muscle Activation Stretching depolarizes the membrane of smooth muscle cells, and this depolarization causes action potentials that activate the contractile mechanism.The neurotransmitters acetylcholine...

The Cytoskeleton

Components Cytoskeleton

In addition to its many membrane-enclosed organelles, the eukaryotic cytoplasm contains a set of long, thin fibers called the cytoskeleton. The cytoskeleton fills at least three important roles It maintains cell shape and support. It provides for various types of cellular movement. Some of its fibers act as tracks or supports for motor proteins, which help move things within the cell. In the discussion that follows, we'll look at three components of the cytoskeleton microfilaments, intermediate...

Functional Subsystems of the Nervous System

Dorsal Ventral Horn Afferent

We have just surveyed the development of the nervous system in terms of anatomically distinct structures. At any one time, these various structures are engaged in many simultaneous tasks a property known as parallel processing of information. Specific tasks are carried out by subsystems that may involve several different anatomical regions or structures of the nervous system. We will now examine several of these functional subsystems. The spinal cord receives and processes information from the...

Ectotherms and endotherms respond differently to changes in environmental temperature

A small lizard can serve as an example of an ectotherm. We can compare it with a mouse, which is an endotherm of the same body size. We can put each animal in a closed chamber and measure its body temperature and metabolic rate as we change the temperature of the chamber from 0 C to 35 C. The results obtained from the two species differ. The body temperature of the lizard equilibrates with that of the chamber, whereas the body temperature of the mouse remains at 37 C Figure 41.7a . The...

Characteristics

Leaf Type Peroxisomes Charophytes

No filamentous stage gametophyte flat Embedded archegonia sporophyte grows basally Filamentous stage sporophyte grows apically from the tip Microphylls in spirals sporangia in leaf axils Differentiation between main axis and side branches Gymnosperms Cycadophyta Ginkgophyta Gnetophyta Pinophyta Compound leaves swimming sperm seeds on modified leaves Deciduous fan-shaped leaves swimming sperm Vessels in vascular tissue opposite, simple leaves Seeds in cones needlelike or scalelike leaves...

Cytoplasmic Determinants

Cytoplasmic Determinants

The embryo is bisected horizontally, separating animal pole cells from vegetal pole cells. The embryo is bisected vertically, leaving each half with both animal and vegetal cells. Cells remain Abnormal larva Normal, but small, larvae embryonic Conclusion The animal and vegetal pole halves differ in their developmental potential. Cells remain Abnormal larva Normal, but small, larvae embryonic Conclusion The animal and vegetal pole halves differ in their developmental potential. 19.7 Asymmetry in...

Membrane Composition and Structure

Integral Membrane Proteins

The physical organization and functioning of all biological membranes depend on their constituents lipids, proteins, and carbohydrates. The lipids establish the physical integrity of the membrane Stephen Hawking The effects of motor neuron disease have confined the famous physicist to a wheelchair. A major cellular manifestation of this disease is the lack of ability of the nerve cells to stimulate the opening of channels through muscle cell membranes that would result in normal muscle...

Ftiii The hormones insulin and glucagon I 0 control fuel metabolism

' f During the absorptive period, blood glucose levels rise as carbohydrates are digested and absorbed. During this time, the P cells of the pancreas release a hormone called insulin see Chapter 42 . Insulin plays a major role in directing glucose to where it will be used or stored. Insulin enhances the uptake of glucose from the blood and its conversion to glycogen by liver and muscle cells. It stimulates fat cells to take up glucose from the blood and convert it to stored fat, and it...

Uptake of mineral ions requires membrane transport proteins

Buildup Muscles

Mineral ions, which carry electric charges, generally cannot move across a membrane unless they are aided by transport proteins explained in Chapter 5 . When the concentration of these charged ions in the soil is greater than that in the plant, ion channels and carrier proteins can move them into the plant by facilitated diffusion, which is a passive process. The concentrations of most ions in the soil solution, however, are lower than those required inside the plant. Thus the plant must take...

Cell Fractionation

Lamina Nuclear

The cell homogenate contains large and small organelles._ The heaviest organelles can be removed and the remaining suspension re-centrifuged until the next heaviest organelles reach the bottom of the tube. 4.8 Cell Fractionation The organelles of cells can be separated from one another after cells are broken open and centrifuged. The heaviest organelles can be removed and the remaining suspension re-centrifuged until the next heaviest organelles reach the bottom of the tube. The nuclear lamina...

Neurulation Initiating the Nervous System

Gastrulation produces an embryo with three germ layers that are positioned to influence one another through inductive interactions. During the next phase of development, called organogenesis, many organs and organ systems develop simultaneously and in coordination with one another. An early process of organogenesis that is directly related to gastrula-tion is neurulation, the initiation of the nervous system in vertebrates . We will examine this event in the amphibian embryo, but it occurs in a...

Chemical digestion begins in the mouth and the stomach

Pepsin Activation

The enzyme amylase is secreted by the salivary glands and mixed with food as it is chewed. Amylase hydrolyzes the bonds between the glucose monomers that make up starch molecules. The action of amylase is what makes a chewed piece of bread or cracker taste slightly sweet if you hold it in your mouth long enough. Most vertebrates can rapidly consume a large volume of food, but digesting that food is a slower process. The stomach stores the consumed food until it can be digested. The se The...

Biological Evolution Changes over Billions of Years

Mammalian Forelimbs

Long before the mechanisms of biological evolution were understood, some people realized that organisms had changed over time and that living organisms had evolved from organisms that were no longer alive on Earth. In the 1760s, the French naturalist Count George-Louis Leclerc de Buffon 1707-1788 wrote his Natural History of Animals, which contained a clear statement of the possibility of evolution. Buffon observed that the limb bones of all mammals were remarkably similar in many details...

Cell Recognition and Adhesion

Complementary Proteins

Some organisms, such as bacteria, are unicellular that is, the entire organism is a single cell. Others, such as plants and animals, are multicellular composed of many cells. Often these cells exist in specialized blocks of cells with similar functions, called tissues. Your body has about 60 trillion cells, arranged in different kinds of tissues such as muscle, nerve, skin, and so forth. Two processes allow cells to arrange themselves in groups Cell recognition, in which one cell specifically...

Development Begins with Fertilization

Cortical Cytoplasm

Fertilization is the union of a haploid sperm and a haploid egg to produce a diploid zygote. Fertilization does more, however, than just restore a full complement of maternal and paternal genes. The entry of a sperm into an egg activates the egg metabolically and initiates the rapid series of cell divisions that produce a multicellular embryo. Also, in many species, the point of entry of the sperm creates an asymmetry in the radially symmetrical egg. This asymmetry is the initiating event that...

Parenchyma cells are alive when they perform their functions

Sclerenchyma Cells

The most numerous cell type in young plants is the parenchyma cell Figure 35.9a . Parenchyma cells usually have thin walls, consisting only of a primary wall and the shared middle lamella. Many parenchyma cells have shapes with multiple faces. Most have large central vacuoles. 35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other materials between cells. 35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other...

Mosses And Ferns Share A Common Trait That Makes Water Droplets A Necessity For Sexual Reproduction. What Is That Trait

Mosses and ferns share a common trait that makes water droplets a necessity for sexual reproduction. What is that trait 2. Are the mosses well adapted to terrestrial life Justify your answer. 3. Ferns display a dominant sporophyte generation with large fronds . Describe the major advance in anatomy that enables most ferns to grow much larger than mosses. 4. What features distinguish club mosses from horsetails What features distinguish these groups from rhyniophytes From ferns 5. Why did...

Materials are exchanged in capillary beds by filtration osmosis and diffusion

Red Cells Squeezing Through Capillary

The walls of capillaries are made of a single layer of thin en-dothelial cells. In most tissues of the body other than the brain, capillaries have tiny holes called fenestrations Latin, anatomical characteristics of blood vessels match their functions. Red blood cells must pass through capillaries in single file. Red blood cells must pass through capillaries in single file. 49.11 A Narrow Lane Capillaries have a very small diameter, and blood flows through them slowly. windows . Capillaries are...

The arrival of a nerve impulse causes the release of neurotransmitter

Nerve Impulse And Acetylcholine

What causes the presynaptic membrane to release neurotransmitter Neurotransmitter is released when a nerve impulse arrives at the axon terminal. The presynaptic membrane contains voltage-gated calcium channels. When a nerve impulse depolarizes the axon terminal, it causes these channels to open see Figure 44.13 . Because Ca2 concentra The acetylcholine receptor-mediated channel is normally closed. When ACh binds at specific sites on the receptor, the channel opens, allowing Na to enter the...

Both marine and terrestrial vertebrates must conserve water

Malpighian Tubules

Some paleontologists believe that the immediate ancestors of the vertebrates lived in fresh water. If that is true, the nephron would have evolved as a structure to excrete excess water. Indeed, the Uric acid precipitates in rectum and is secreted. Uric acid precipitates in rectum and is secreted. Semisolid wastes including uric acid Uric acid, Na , and K are transported into the Malpighian tubules H2O follows. Semisolid wastes including uric acid Uric acid, Na , and K are transported into the...

Blood and lymph tissues play important roles in defense systems

Thoracic Conduct Lymph

The components of the mammalian defense system are dispersed throughout the body and interact with almost all of its other tissues and organs. The lymphoid tissues, which include the thymus, bone marrow, spleen, and lymph nodes, are essential parts of the defense system Figure 18.1 , but central to their functioning are the blood and lymph. Blood and lymph are both fluid tissues that consist of water, dissolved solutes, and cells. Blood plasma is a yellowish solution containing ions, small...

Organelles that Process Energy

Leucoplast

A cell uses energy to synthesize cell-specific materials that it can use for activities such as growth, reproduction, and movement. Energy is transformed from one form to another in mitochondria found in all eukaryotic cells and in chloro-plasts found in eukaryotic cells that harvest energy from sunlight . In contrast, energy transformations in prokaryotic cells are associated with enzymes attached to the inner surface of the plasma membrane or extensions of the plasma membrane that protrude...

Nitrogenase catalyzes nitrogen fixation

Plant Root Bacteroid Nitrogenase

Nitrogen fixation is the reduction of nitrogen gas. It proceeds by the stepwise addition of three pairs of hydrogen atoms to N2 Figure 37.6 . In addition to N2, these reactions require The enzyme nitrogenase binds a molecule of nitrogen gas. 2 A reducing agent transfers three successive pairs of hydrogen atoms to N2. 37.6 Nitrogenase Fixes Nitrogen Throughout the chemical reactions of nitrogen fixation, the reactants are bound to the enzyme nitrogenase. A reducing agent transfers hydrogen atoms...

Many stems and roots undergo secondary growth

Primary Growth Woody Stems

Some stems and roots remain slender and show little or no secondary growth. However, in many eudicots, secondary growth thickens stems and roots considerably. This process gives rise to wood and bark, and it makes the support of tall trees possible. Secondary growth results from the activity of the two lateral meristems vascular cambium and cork cambium see Figure 35.13 . Vascular cambium consists of cells that divide to produce secondary xylem and phloem cells, while cork cambium produces...

Detecting Stimuli that Distort Membranes

Transduction Sound Auditory Nerve

Mechanoreceptors are cells that are sensitive to mechanical forces. Physical distortion of a mechanoreceptor's plasma membrane causes ion channels to open, altering the membrane potential of the cell, which in turn leads to the generation of action potentials. The rate of action potentials tells the CNS the strength of the stimulus exciting the mechanorecep-tor. Mechanoreceptor cells are involved in many sensory systems, ranging from skin sensations to sensing blood pressure. Sensory cells use...

Diversity in the Kingdom Fungi

Rhizopus Life Cycle Figure

In this section on fungal diversity, we'll consider four phyla Chytridiomycota, Zygomycota, Ascomycota, and Basid-iomycota Figure 31.6 Table 31.1 . The first two groups are probably not clades, but the Ascomycota and Basidiomycota are clades. Chytrids probably resemble the ancestral fungi The earliest-diverging fungal group is the chytrids phylum Chytridiomycota . These aquatic microorganisms were formerly classified with the pro- tists. However, morphological cell walls Basidiomycota I that...

Melatonin is involved in biological rhythms and photoperiodicity

The pineal gland is situated between the two hemispheres of the brain and is connected to the brain by a little stalk. It produces the hormone melatonin from the amino acid tryp-tophan. The release of melatonin by the pineal occurs in the dark and therefore marks the length of the night. Exposure to light inhibits the release of melatonin. In various vertebrates, melatonin is involved in biological rhythms, including photoperiodicity the phenomenon whereby seasonal changes in day length cause...

Fertilization Of Flowers

Magnoliid Example

30.7 A Generalized Flower Not all flowers possess all the structures shown here, but they must possess a stamen bearing microsporangia , a pistil containing megasporangia , or both in order to play their role in reproduction. Flowers that have both, as this one does, are referred to as perfect. mens, and carpels which are referred to as the floral organs see Figure 19.12 are usually positioned in circular arrangements or whorls and attached to a central stalk called the receptacle. The...

Eukarya

Archaea High Pressure Lovers

Three of the bacterial groups that may have branched out earliest during bacterial evolution are all thermophiles heat lovers , as are the most ancient of the archaea. This observation supports the hypothesis that the first living organisms were thermophiles that appeared in an environment much hotter than those that predominate today. The Proteobacteria are a large and diverse group By far the largest group of bacteria, in terms of numbers of described species, is the proteobacteria, sometimes...

The pituitary is closely associated with the brain

Neurohormonal Regulation

The pituitary gland sits in a depression at the bottom of the skull just over the back of the roof of the mouth Figure 42.5 . It is attached by a stalk to the part of the brain called the hypothalamus, which is involved in many homeostatic regulatory systems see Chapter 41 . The pituitary has two distinct parts that have different functions and separate origins during development. The anterior pituitary originates as an outpocketing of the embryonic mouth cavity, and the posterior pituitary...

Heart Rate Chemoreceptor

Regulating Blood Pressure

Circulating renin activates angiotensin 49.18 Control of Blood Pressure through Vascular Resistance A drop in arterial pressure reduces blood flow to tissues,resulting in local accumulation of metabolic wastes.This change in the extracellular environment stimulates autoregulatory opening of the arteries and would lead to a further decrease in central blood pressure if this were not prevented by the negative feedback mechanisms shown in this diagram, which work by promoting the constriction of...

Ribbon worms are unsegmented

Earthworm Muscular Circular

The carnivorous ribbon worms phylum Nemertea are dorsoventrally flattened. They have nervous and excretory systems similar to those of flatworms, but unlike flatworms, they have a complete digestive tract with a mouth at one end and an anus at the other. Food moves in one direction through the digestive tract and is acted on by a series of digestive enzymes. Small ribbon worms move by beating their cilia. Larger ones employ waves of muscle contraction to move over the surface of sediments or to...

Reptilian lineages diverged

Plates Amniotes

The lineages leading to modern reptiles began to diverge about 250 mya. One lineage that has changed very little over the intervening millenia is the turtles subclass Testudines . Turtles have a combination of ancestral traits and highly specialized characteristics that they do not share with any other vertebrate group. For this reason, their phylogenetic relationships are uncertain. The dorsal and ventral bony plates of modern turtles and tortoises form a shell into which the head and limbs...

Fj Cnidarian life cycles have two stages

Different Stages Sperm Development

X J The generalized cnidarian life cycle has two distinct stages Figure 32.8 , although many species lack one of these stages The sessile polyp stage has a cylindrical stalk attached to the substratum. Tentacles surround a mouth anus located at the end opposite from the stalk. Individual polyps may reproduce by budding, thereby forming a colony. As the positions of the mouth and tentacles indicate, the medusa is upside down from the polyp or vice versa. 32.8 A Generalized Cnidarian Life Cycle...

The postsynaptic cell sums excitatory and inhibitory input

Postsynaptic Cell Spatial Summation

Individual neurons can decide whether or not to fire an action potential by summing excitatory and inhibitory postsynaptic potentials. This summation ability is the major mechanism by which the nervous system integrates information. Each neuron may receive a thousand or more synaptic inputs, but it has only one output an action potential in a single axon. All the information contained in all the inputs a neuron receives is reduced to the rate at which that neuron generates nerve impulses in its...

Noncyclic electron transport produces ATP and NADPH

Photosystem Produces

In noncyclic electron transport, light energy is used to oxidize water, forming O2, H , and electrons. Follow the steps in Figure 8.9 as you read this section. tached to each ribose see Figure 7.4 . Whereas NAD partic- 8.9 Noncyclic Electron Transport Uses Two Photosystems Photosystems I and II both make use of the excited chlorophyll molecules of their respective reaction centers. 5 Photosystem I reduces an oxidizing agent, ferredoxin Fd , which in turn reduces NADP to NADPH H . Electrons from...

Information Processing by Neuronal Networks

Ganglion Sympathetic System

The functions of the nervous system can be understood in terms of neuronal networks. In this section we will use two subsystems of the nervous system to demonstrate the functioning of such networks. The first example, the autonomic nervous system, consists of efferent pathways the second, the visual system, consists of afferent and integrative pathways. Techniques that have allowed neurobiologists to trace neuronal connections, identify neurotransmitters at synapses, and record action...

Segmentation improved locomotion in the annelids

Trochophore

Segmentation allows an animal to alter the shape of its body in complex ways and to control its movements more precisely. Fossils of segmented worms are known from the middle Cambrian the earliest forms are thought to have been burrowing marine animals. Segmentation evolved several times among spiralians we will discuss only one of the phyla with segmented members the annelids. The annelids phylum Annelida are a diverse group of segmented spiralian worms Figure 32.22 . The coelom in each...

Sponges Loosely Organized Animals

Coelomate Body Plan

The lineage leading to modern sponges separated from the lineage leading to all other animals very early during animal evolu tion. The difference between pro tist colonies and simple multicellu lar animals is that the animal cells are differentiated and their activities are coordinated. However, sponge cells do not form true organs. Acoelomates do not have enclosed body cavities. Pseudocoelomates have a cavity lined with mesoderm on the outer side, but no mesoderm surrounds the internal organs....

Action potentials can jump down axons

Action Potential Refractory

In vertebrate nervous systems, increasing the speed of action potentials by increasing the diameter of axons is not feasible because of the huge number of axons in these organisms. Each of our eyes, for example, has about a million axons extending from it. Evolution has increased action potential velocity in vertebrate axons in a way that does not require large size. When we described glial cells earlier in the chapter, we saw that certain glial cells wrap themselves around axons, covering them...

Research Method

Freeze Fracture Method Plasma Membrane

5.3 Membrane Proteins Revealed by the Freeze-Fracture Technique This membrane from a spinach chloroplast was first frozen and then separated so that the membrane bilayer was split open. both. This arrangement gives the two surfaces of the membrane different properties. As we will soon see, these differences have great functional significance. Like lipids, many membrane proteins move around relatively freely within the phospholipid bilayer. Experiments using the technique of cell fusion...

Adaptations for Respiratory Gas Exchange

Adaptation For Respiratory Gas Exchange

Now that we know the physical factors that influence the rates of diffusion of respiratory gases between an animal and its environment, let's take a look at some of the adaptations animals have evolved for maximizing their respiratory gas exchange. They include adaptations for increasing the surface area over which diffusion of gases can occur, maximizing partial pressure gradients, and minimizing the diffusion path length through an aqueous medium. Respiratory organs have large surface areas...

Gastrulation Producing the Body Plan

Human Gastrulation

The blastula is typically a fluid-filled ball of cells. How does this simple ball of cells become an embryo, made up of multiple tissue layers, with head and tail ends and dorsal and ventral sides Gastrulation is the process whereby the blastula is transformed by massive movements of cells into an embryo with multiple tissue layers and visible body axes. The resulting spatial relationships between tissues make possible the inductive interactions that trigger differentiation and organ formation....

The ethylene signal transduction pathway is well understood

Ethylene Signal Transduction Pathway

Analysis of Arabidopsis mutants has revealed the steps in the mechanism of ethylene action. Some of these mutants do not respond to applied ethylene, and others act as if they have been exposed to ethylene even though they have not. Studies of the mutant genes and their protein products, coupled with comparisons of their amino acid sequences with those of other known proteins, have revealed some of the details of the signal transduction pathway through which ethylene produces its effects Figure...

The Endomembrane System

Golgi Complex Packing And Transporting

Much of the volume of some eukaryotic cells is taken up by an extensive endomembrane system. This system includes two main components, the endoplasmic reticulum and the Golgi apparatus. Continuities between the nuclear envelope and the endomembrane system are visible under the electron microscope. Tiny, membrane-surrounded droplets called vesicles appear to shuttle between the various components of the endomembrane system. This system has various structures, but all of them are essentially...

The Surviving Nonseed Tracheophytes

Tracheophytes Psilophyta Whisk Fern

The nonseed tracheophytes have a large, independent sporo-phyte and a small gametophyte that is independent of the sporophyte. The gametophytes of the surviving nonseed tra-cheophytes are rarely more than 1 or 2 centimeters long and are short-lived, whereas their sporophytes are often highly visible the sporophyte of a tree fern, for example, may be 15 or 20 meters tall and may live for many years. The most prominent resting stage in the life cycle of a non-seed tracheophyte is the...