Number Of Genes

Transcription control RNA processing Nerve impulse transmission Tissue formation Cell interactions

Cell-cell signaling

Zinc finger; homeobox RNA binding domains Gated ion channels Collagens

Extracellular domains;

glycotransferases G protein-linked receptors; protein kinases; protein phosphatases

The puffer fish is a vertebrate with a compact genome

The puffer fish, Fugu rubripes, is prized in the culinary world as a gourmet item from Japan that must be carefully prepared, as it contains a lethal poison called tetrodotoxin that inhibits membrane channels in nerve cells. In the biological world, it is prized for its genome, which is the most compact known among vertebrates. It has 365 million base pairs and about 30,000 genes. The human genome has one-third fewer genes in eight times the amount of DNA.

A comparison of the human and puffer fish genomes showed that many genes in the two organisms are similar, so that, as lead scientist Sydney Brenner (who also led the study of the C. elegans genome) put it, "the Fugu genome is the 'Reader's Digest version of the Book of Man.'" A major difference between the two genomes is in repetitive DNA sequences, which make up 40 percent of the human genome but a much smaller proportion in the puffer fish. The significance of this finding is unknown. Of course, humans are obviously much more complex than fish; how we accomplish this with a set of genes that is even smaller in number than the fish's is not known, but certainly points up the fact that it is not genes alone that determine the complexity of an organism.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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