LS4 MT1 practice

LS4 MT1 practice - 1 LS 4 Example Midterm 1 questions...

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Unformatted text preview: 1 LS 4 Example Midterm 1 questions INTRODUCTORY GENETICS 2 1. Mitosis/Meiosis We consider an organism with three pairs of chromosomes: the sex chromosomes X and Y, and the pairs of autosomal chromosomes 1 and 2. The female is the heterogametic sex. The structure of these chromosomes (shown as one-chromatid-chromosomes) is shown below. Y X 1 2 1A. Draw the expected arrangement of chromosomes at metaphase of meiosis I in a male. Indicate and label chromosomes and centromeres. 1B. Draw the expected arrangement of chromosomes at metaphase of mitosis in a female. Indicate and label chromosomes and centromeres. 1A. 1B. equatorial plane, metaphase plate 3 2. Pedigree The following pedigree concerns a very rare human disorder that causes premature puberty in males. 1 2 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Which mode(s) of inheritance can explain the above pedigree (circle the correct answer; there may be more than one correct answer). ASSUME COMPLETE PENETRANCE EXCEPT FOR F. A A. B. C. D. E. F. B C D E F Autosomal Dominant Autosomal Recessive X-linked dominant X-linked recessive Y-linked Y-linked with incomplete penetrance 3. In human beings, the absence of molars is inherited as a dominant trait. If two heterozygotes have four children, what is the probability that: 6A. all will have no molars? Show your calculation. 6B. the first two will have molars and the second two will have no molars? Show your calculation. 4 4. ABO pedigree A human pedigree is shown below. The ABO blood types of some of the members of the family are shown. I 1 A 2 II O 1 2 O 3 AB 4 III B 1 2 3 IV 1 A. For the individuals listed below, circle their correct genotype. If there is more than one possible genotype, then circle all of the possibilities. Individual I- 1 Possible Genotypes IAIA IAIB IBIB IAi IAIA IAIB IBIB IAi IAIA IAIB IBIB IAi IAIA IAIB IBIB IAi IBi IBi IBi IBi ii II-2 ii III-1 ii IV-1 ii B. What is the probability that IV-1 will have blood type AB? (circle the correct answer) 1 15/16 7/8 3/4 5/8 9/16 1/2 7/16 3/8 5/16 1/4 3/16 1/8 1/12 1/16 1/32 1/64 0 (none of above) 5 5. Consider the following pedigrees from human families containing a male with Klinefelter syndrome ( a set of abnormalities seen in XXY individuals; indicated as black boxes). In each, A and B refer to codominant alleles of the X-linked G6PD gene. The phenotypes of each individual (A, B, or AB) are shown in the pedigree. Indicate if non-disjunction occurred in the mother or the father of the child with klinefelter syndrome for each of the three examples. Can you tell if the non-disjunction was in the first or the second meiotic division? Fill answers into the provided boxes. A 5A B nondisjunction in mother or father, or can be in either AB non-disjunction in meiosis I or II, or can be in either AB 5B AB AB A A AB 5C A A B A 6 6. Crosses Consider a cross between the following two genotypes: a/a; B/b; c/c; D/d; E/e X a/a; b/b; C/c; D/d; E/E 6A. What proportion of progeny will be genotypically the same as the first parent. Show your work/calculations to get full credit. 6B. What proportion of progeny will be phenotypically the same as the first parent. Show your work/calculations to get full credit. 6C. What proportion of progeny will be genotypically different from both parents. Show your work/calculations in detail to get full credit. ...
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This note was uploaded on 04/15/2010 for the course LS LS 4 taught by Professor Ribaya during the Winter '07 term at UCLA.

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