bio214c - Biology 214/414 2009 Packet#2 Suggested problems...

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Biology 214/414 2009 Packet #2 Suggested problems: Chapter 3: 1, 2, 6, 7, 8, 12, 18, 20, 22, 26, 28, 30, 34 Chapter 4: 1, 2, 4, 6, 10, 12, 16, 20, 24, 30, 32, 34 Mendelian genetics I. The beginning of modern genetics and the basis for our understanding of genetics starts with Mendel’s discoveries of the 1850’s-1860’s. II. Mendel established the inheritance of traits via physical units (which we now call “genes ”), although the physical/chemical basis for these traits was unknown. a. In a way this is analogous to seeing an animal track in the snow and knowing that a physical entity (ie, an animal) must have made the track, even though you don’t know what the animal was/looked like. b. He worked with single inherited traits in garden peas ( Figure 3- 1 ), and worked on (or reported) only the simplest cases: i. “unlinked ” genes ii. traits determined by only one gene iii. “simple dominance III. What Mendel figured out was essentially as follows; for cells of “higher ” life forms (everything above bacteria): a. Genes come in pairs (with some exceptions). i. There are two copies of each of 1000’s of genes. ii. The copies can be identical. iii. The two copies may be slightly different forms of each other (“alleles ”); one gene may have many different alleles if the entire population is considered. ( Table 4.2 ) 1. For example, for gene x, one individual may be x 1 x 2 , a second may be x 1 x 3 , a third may be x 4 x 5 , etc. iv. While not exactly the same, gene and allele are often used interchangeably.
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b. During generation of gametes (meiosis) members of each pair of genes separate from each other, each one to a separate gamete. This is known as “Mendel’s first law ”. c. Separation of members of a pair is random and (to a first approximation) members of one pair of genes separate independently of all other gene pairs. This is known as “Mendel’s second law ”. d. An important corollary to Mendel’s laws is that a pair of genes comes together again when the egg meets the sperm to form a “zygote ”, and ultimately a new individual. IV. Symbols/terminology/mechanisms of analysis a. A “mutant ” trait/allele is one that differs from the “wild type ”, which is the most common form of the trait/allele. b. Mutants are usually (but not necessarily) “recessive ”; when present as a pair, a recessive trait/allele is masked by a “dominant ” trait/allele. c. Alleles behave according to the laws of probability, particularly the law that states that the probability of >1 independent events occurring = the product of the probability of each individual event. d. For example: D, d are the alleles for the gene determining pea plant height, with D dominant and d recessive, D determining tall plants and d, dwarf plants. i.
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This note was uploaded on 03/03/2010 for the course BIOL 214 taught by Professor Stark during the Fall '06 term at Illinois Tech.

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bio214c - Biology 214/414 2009 Packet#2 Suggested problems...

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