Review Activities

Test Your Knowledge of Terms and I

1. According to the fluid-mosaic model of the plasma membrane a. protein and phospholipids form a regular, repeating structure.

b. the membrane is a rigid structure.

c. phospholipids form a double layer, with the polar parts facing each other.

d. proteins are free to move within a double layer of phospholipids.

2. After the DNA molecule has replicated itself, the duplicate strands are called a. homologous chromosomes.

b. chromatids.

c. centromeres.

d. spindle fibers.

3. Nerve and skeletal muscle cells in the adult, which do not divide, remain in the a. Gj phase.

4. The phase of mitosis in which the chromosomes line up at the equator of the cell is called a. interphase.

b. prophase.

c. metaphase.

d. anaphase.

e. telophase.

5. The phase of mitosis in which the chromatids separate is called a. interphase.

b. prophase.

c. metaphase.

d. anaphase.

e. telophase.

6. Chemical modifications of histone proteins are believed to directly influence a. genetic transcription.

b. genetic translation.

c. both transcription and translation.

d. posttranslational changes in the newly synthesized proteins.

7. Which of these statements about RNA is true?

a. It is made in the nucleus.

b. It is double-stranded.

c. It contains the sugar deoxyribose.

d. It is a complementary copy of the entire DNA molecule.

8. Which of these statements about mRNA is false?

a. It is produced as a larger pre-mRNA.

b. It forms associations with ribosomes.

c. Its base triplets are called anticodons.

d. It codes for the synthesis of specific proteins.

9. The organelle that combines proteins with carbohydrates and packages them within vesicles for secretion is a. the Golgi complex.

b. the granular endoplasmic reticulum.

c. the agranular endoplasmic reticulum.

d. the ribosome.

10. The organelle that contains digestive enzymes is a. the mitochondrion.

b. the lysosome.

c. the endoplasmic reticulum.

d. the Golgi complex.

11. Which of these descriptions of rRNA is true?

a. It is single-stranded.

b. It catalyzes steps in protein synthesis.

c. It forms part of the structure of both subunits of a ribosome.

d. It is produced in the nucleolus.

e. All of these are true.

12. Which of these statements about tRNA is true?

a. It is made in the nucleus.

b. It is looped back on itself.

c. It contains the anticodon.

d. There are over twenty different types.

e. All of these are true.

13. The step in protein synthesis during which tRNA, rRNA, and mRNA are all active is known as a. transcription.

b. translation.

c. replication.

d. RNA polymerization.

14. The anticodons are located in a. tRNA.

d. ribosomes.

e. endoplasmic reticulum.

Test Your Understanding of Concepts and Principles

1. Give some specific examples that 5. illustrate the dynamic nature of the plasma membrane.1

2. Describe the structure of nucleosomes, 6. and explain the role of histone proteins in chromatin structure and function.

3. What is the genetic code, and how does it affect the structure and function of the body? 7.

4. Why may tRNA be considered the "interpreter" of the genetic code?

Compare the processing of cellular proteins with that of proteins secreted by a cell.

Explain the interrelationship between the endoplasmic reticulum and the Golgi complex. What becomes of vesicles released from the Golgi complex?

Explain the functions of centrioles in nondividing and dividing cells.

Test Your Ability to Analyze and Apply Your

1. Discuss the role of chromatin proteins 3. in regulating gene expression. How does the three-dimensional structure of the chromatin affect genetic regulation? How do hormones influence genetic regulation?

2. Explain how p53 functions as a tumor suppressor gene. How can mutations in p53 lead to cancer, and how might 4.

gene therapy or other drug interventions inhibit the growth of a tumor?

Knowledge

Release of lysosomal enzymes from white blood cells during a local immune attack can contribute to the symptoms of inflammation. Suppose, to alleviate inflammation, you develop a drug that destroys all lysosomes. Would this drug have negative side effects? Explain. Antibiotics can have different mechanisms of action. An antibiotic called puromycin blocks genetic translation. One called actinomycin D

8. Describe the phases of the cell cycle and explain how this cycle may be regulated.

9. Distinguish between oncogenes and tumor suppressor genes and give examples of how such genes may function.

10. Define apoptosis and explain the physiological significance of this process.

blocks genetic transcription. These drugs can be used to determine how regulatory molecules, such as hormones, work. For example, if a hormone's effects on a tissue were blocked immediately by puromycin but not by actinomycin D, what would that tell you about the mechanism of action of the hormone?

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Good Carb Diet

Good Carb Diet

WHAT IT IS A three-phase plan that has been likened to the low-carbohydrate Atkins program because during the first two weeks, South Beach eliminates most carbs, including bread, pasta, potatoes, fruit and most dairy products. In PHASE 2, healthy carbs, including most fruits, whole grains and dairy products are gradually reintroduced, but processed carbs such as bagels, cookies, cornflakes, regular pasta and rice cakes remain on the list of foods to avoid or eat rarely.

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Responses

  • Edoardo Padovano
    Why may trna be considered the interpreter of genetic code?
    8 years ago
  • Are proteins free to move within a double layer of phospholipids?
    8 years ago
  • Stephanie
    What are some specific examples that illustrates the dynamic nature of the plasma membrane?
    8 years ago
  • sarah
    What step in protein synthization are mRNA, tRNA, and rRNA all active?
    7 years ago
  • tanja rosendahl
    What step in protein synthesis during which tRNA rRNA and mRNA are all active?
    6 years ago

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