genetics - Introduction to Genetics Reading: Freeman,...

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Introduction to Genetics Reading: Freeman, Chapter 13 (read twice, do all the questions at the back of the chapter), also Chapter 12 (to review meiosis, mostly)
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Information Genetics is, quite simply, the study of the process by which information is transmitted from one generation of living things to the next. Every living thing is organized via coded information, called its genetic material . Reproduction involves duplication and transmission of an organisms genetic material.
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WHAT IS A GENE? A gene is an information entity. It is a sequence of DNA that codes for a single genetic instruction. Usually, this instruction is the sequence of a protein, but a gene may also serve to activate or deactivate other genes, in a cell, or in neighboring cells. Every aspect of our species is constructed based on information encoded in genes. The genes themselves do very little, they are information storage molecules. It is the cytological machinery of our cells, passed from one generation to the next, that translate these instructions into a living organism. The effects of every gene depend both upon other genes, and upon the environment.
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What is an allele? An allele is ONE variant of a gene. Many genes have two, several, or many different variants of the same basic genetic information. Some alleles are minor differences that to not significantly affect the organism, others cause profound changes .
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Example: Nucleotide substitutions in the third codon position often produces no change at all, because they code for the same transfer RNA and thus the same protein is produced. In humans…CCU CCA does not cause a change, both triplets code for proline. Other substitutions may produce profound effects, sickle cell anemia is caused by a single nucleotide substitution: GAG GUG changes normal hemoglobin to hemoglobin that “sickles” under low oxygen concentrations.
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Prokaryotes , which include the archaea and bacteria, are the simplest, oldest, and most common organisms on the planet. A typical prokaryote has a much smaller genome than a typical eukaryote. Nearly always, it is in the form of a simple loop of DNA (with associated proteins). This loop is attached to the cell membrane. Even though the structure simple, there is a lot of DNA in a single bacterium. .… Stretched out, the DNA in an E. coli would be 500 times longer than the cell itself. Prokaryotes do not have sexual reproduction, though they have several forms of gene exchange. These include swapping plasmids
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The various genes, about 1200 in a typical bacterium, are arranged along the length of the chromosome, like beads on a string. There is no particular functional grouping to their order, it is mostly evolutionary chance that determines their location In prokaryotes, the DNA loop replicates before fission, with both loops still attached to the cell membrane During fission, as the cell membrane splits in two, one loop of DNA ends up in each new “daughter cell” Thanks to/stolen from fig.cox.miami.edu
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genetics - Introduction to Genetics Reading: Freeman,...

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