BIO325 exam1 2007

BIO325 exam1 2007 - Twit/(my Wm THC UQ $ GENETICS (BIO...

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Unformatted text preview: Twit/(my Wm THC UQ $ GENETICS (BIO i325) SUMMER 2007 1 Exam 6/12/07 Total points: 120 There are 24 questions in this exam. Each question carries 5 points. Answer all 24 questions for a maximum of 120 points. Select only ONE answer in questions with multiple choices. 1. The allele 6 causes albinism in mice (C causes mice to be black). lfthe cross (7% x 0/6 is made. and there are 10 progeny, what is the probability that all the progeny will be black? Cc IC ere 8C5 (C 2. A couple without an ancestral history of Tay-Sachs disease (an autosomal recessive) have two normal children and an infant affected with Tay-Sachs. The sister ofthe husband wants to marry the brother ofthe wife; in such a mating. wrfirat Brould be the prgga‘bihtytaitheirkfi ‘t ch'tleAli’aving Tay-Sachs disease? n P in Ii 0 w P“ a AA 1 [2 3 A human disease afflicted a family as shown in the following pedigree. a X“ xh XL Y KfixhxpyA Wt I f/ What is the most likely mode of inheritance ofthis tlisea‘ ' . | 4. A/A 6/b An A an M /\ M. fl‘“ 5. 6. 7. In moss, the genes A and B are expressed only in the gametophyte. A sporophyte of genotype A/a; B/h is allowed to pr uce gametophytes. (i) What proportion of the etophytes will be A; B? “4 AB K/q fififi (iif‘b If fertilization is random, what proportion of sporophytes in the next generation will be A/a; B/b? Answer if the following statements are true or false: (a) Homologous chromosomes carry alleles for the same genes in the same relative positions. ’( Ht 2 (b) Homologous chromosomes regularly ex meiosis. TWA Q (C) Homologous chrom somes ph (d) Homologous chrom some re found in pairs but they do not physically pair in interphase in a di 10' ’(VMQ (e) Homologous chromosomes duplicate before entering prophase of mitosis such that each chromosome has two chromatids. Tyme nge parts by crossing over at air at mitosis. {A UK The black and yellow pigments in the coats of cats are controlled by an X-linked pair of alleles. Females heterozygous for these alleles have areas of black and areas of yellow in their coat (called tortoise-shell. or calico if there are also patches of white hair). (i) A calico cat has a litter of eight kittens: 1 yellow male, 2 black males, 2 yellow females, and 3 calico fe es. Assuming there is a single father for the litter, what is his proba color? \ x“ Y XAXDN Ox K X”X _ , : 1 yellow and 3 calico. Assuming , what is the probable sex of the yellow X“xe l X“me-X“V % X'W“ (ii) A yellow cat has a litter of four kitte there is a single father for the litt kitten? A trihybrid cross is a cross between two individuals that are heterozygous for three genes. Ber example: A/a - B/b - C/c x A/a - B/b - C/c. Assuming these three genes are linked and assorting independently, what phenotypic ratio would be in the offspring resulting from this cross? ,,_. l6:9:9:3:3:l ijooaayai (6)12r913zl 23:24 8. . “9% 1 :: /"¢ /‘ ¢ 1;: ’S N” /’.T f l 9. 10. (i) In a plant in which/211 = 2.3. what is the total number of chromatids present during prophase I ofmeiosis? (i) Identify the most likely mode of inheritance (autos ominant, autosomal recessive, X-liWant. X-linked recessive, cypplasmic) for the following pedigree. A A A“ am A AMAH ,1 f/l fhfl (ii) What is the probability that individuals Ill-1 and 111-4 will ha ' affected child if they decide to get married? V2 X VZX V4 : an Indicate whether the following statements are true or false. (a) The DNA ofa eukaryotic chromosome is one long double helix. l p we 1n the middle of a eukaryotic chromosome. Mite (c) A telomerej ways on the end ofa eukaryotic chromosome. / {wmé (d) Histones are rich in basic amino acids. ’A True (e) Each eukaryotic chromosome has multiple origins of replication. TWMQ (b) A centromere is alwa l 1. In a dihybrid (A/a;B/l)) the genes shown are located on different chromosomes. Which one ofthe following diagrams does répresent a stage of meiosis in this organism? ‘ (Note: For each answer only some chromatids may be represented.) Na XV A wWNj/ b g L A '1 b: I B , 16 to we a huff/8’ ”“ A l/«ex/s A W N 12. Tall. yellow-flowered crocus is mated with short. white-flowered crocus. Both varieties are true breeding. All the F. plants are testcrossed with the short, white— flowered variety. This backcross yielded 214 tall yellow, 223 tall white, 195 short yellow, and 188 short white plants. Perform a chi-square test to determine if the observed result fits the hypothesis of a 121:1:1 segregation. (i) What is the chiysquare value in this exar‘nglefi’j ‘ 3 ‘04 hat are the degrees of freedom in this example? a (tug; WW :1 ELM/hat is the approximate probabilitl Pvalue from the given table. . I z. \0 L #3 ’X, . 3 (iv) Based on the P value, is the hypothesis accepted or rejec ed? / 20$ ‘1 (at we leg «to too “We ‘ "’i"/’ ' ’ ' v 2 3011 S 3* 'i ‘3‘ Table 3-1 Critical Values of the x2 Distribution ll?! 25 l ‘ t 1 p df 0.995 0.975 0.9 0.5 0.1 0.05 0.025 0.01 0.005 df 1 .000 .000 0.016 0.455 2.706 3.841 5.024 6.635 7.879 1 2 0.010 0.051 0.211 1.386 4.605 5.991 7.378 9.210 10.597 2 3 0.072 0.216 0.584 2.366 6.251 7.81 5 9.348 11 .345 12.838 3 4 0.207 0.484 1.064 3.357 7.779 9.488 11.143 13.277 14.860 4 5 0.412 0.831 1.610 4.351 9.236 11.070 12.832 15.086 16.750 5 6 0.676 1.237 2.204 5.348 10.645 12.592 14.449 16.812 18.548 6 7 0.989 1.690 2.833 6.346 12.017 14.067 16.013 18.475 20.278 7 8 1.344 2.180 3.490 7.344 13.362 15.507 17.535 20.090 21.955 8 9 1.735 2.700 4.168 8.343 14.684 16.919 19.023 21.666 23.589 9 10 2.156 3.247 4.865 9.342 15.987 18.307 20.483 23.209 25.188 10 11 2.603 3.816 5.578 10.341 17.275 19.675 21.920 24.725 26.757 11 12 3.074 4.404 6.304 11.340 18.549 21.026 23.337 26.217 28.300 12 13 3.565 5.009 7.042 12.340 19.812 22.362 24.736 27.688 29.819 13 14 4.075 5.629 7.790 13.339 21.064 23.685 26.119 29.141 31.319 14 1 5 4.601 6.262 8.547 14.339 22.307 24.996 27.488 30.578 32.801 15 3. The maize genes 3'11 and b2 are linked and are 40 map units apart. If a plant with the genotype is sh z Wsh z is testcrossed. what proportion of the progeny will have the genotype: (i) sh bz/sh b: 96 be , “Z L‘LTJ 2/ (ii) sh'bz/sh bz _ r: l'.”l:_~,l£, 2’; 14. A fruit fly of genotype B R/b r is crossed to a fly with the genotype b M) r. In 84 percent ofthe meioses, there are no chiasmata between the linked genes; in 16 percent of the meioses, there is one chiasma between the linked genes. What proportion of the progeny from this cross will have the genotype B N) r? B P— .__l2__L__ b "if lo \/ 15. In maize, two plants that are botliwheterozygous for the recessive alleles a and b are crossed. What frequency of double-mutant progeny (a In: b) will ap eat if a and b are 7.2 map units apart, and both parents are dihybrids in the ns confi vuratio 1' L e 2 g it’ll— ..EE—h l2 / fig- 03% ” ’ fl”? 7‘ w i i s l i“ 0 73 L0 " 0 so 2 n in ~13.7, V ’ .017, .oaox. owflo . 0012 “ital 16. 17. 18. I Indicate whether the following statements are true or false. (a) The smaller the propoltiin‘of recombinants‘inthe progeny, the tighter the linkage of genes. «(a M Q (b) The maximum r/ecombination between two loci on a single chromosome is 50% becau only two of the four associated chromatids participate in an indivi recombination event. TB [/1 Q (c) Pl ' tropism is the situation in wMgmmfiemtwo or more unrelated spects of a phenotype. 1%. me For X-linked dominant traits, affected sons always have affected mothers/[’K/[A6 A dihybrid genotype is represented as A/B; a/b. pa [5‘ Q ( (e) In a testcross of a female Drosophila heterozygous for three linked genes, th following phenotypes of progeny were obtained: a bid 413-7? 01” Wfll 10L +01 “32:. 4?: m be” baidt a , / a_ bi d 12 m0 SRO 0‘ Vt 0, mt“ ({de 19 m 1 + .m abld 20 await brawl in ’ alfdd (1)7NO Mf/ a m (’k lodl Construct a genetic map showing the order of the genes and the distance between adjacent genes. U U + + W (l U. \(loo ‘ ‘ l m at M f 12H? + d _ - “ i m Clx mt- 2'1}? (0 ’ . , r EM; HHZM— 1X20“ 0” V 0(00 If 44 I ll .1 A segment of map a ----- --b ----------- —-c is shown, where the distance between a and b is 10 map units, and the distance between b and c is 20 map units. With 40% interference, what would be the observed frequency of double crossovers? ‘q Mil/(.04 (Ocau ,— l9. ‘ In Neurmpora, a linear biochemical pathway synthesizes an amino acid Z. » E1, E2, and E3 are enzymes that catalyze the three reactions. E1 E2 E3 W—>X—>Y—+Z Null mutants for the gene encoding enzyme E2 will grow on minimal medium supplemented compounds (c) WorXorYorZ (d) 2 only (e) W only 20. Describe briefly the experiments performed by Beadle and Tatum that led to the one-gene-one-enzyme hypothesis. Mention the organism that they used for their V studies and the kind of mutants that they analyzed. I ‘ Mfg ,6 W ‘41m.m_._3 I. W A“, mm} ’ Wl/MMP) \ ile will wit/mm! (. El” ‘ A, “h” “UT 4 Tm; \Afitl WWW! l WVQ (Om 0m + W») WNW Walll’ I f c [Mimi/d A t m MmMMML ‘ WWW M a 14 4mm W1 WlMH/vtal Wad/ltLWN Numwcwm Ul/LCL) l , a A ' (3 M7 “ mw’> tall/littqmeh mutt wlflflct h a. {mm W JVWVWWM MAE/m Yum/\th V wad he ale M{WWWMOU thh/UW, W WWW,meWwflwmwmeWW " ‘ I'll I .. an uuw [Mal malt/HM WWW Mariam“ Macmt‘W’W WWW/Ur we vw Wm M MW, [9154er powwow, ‘ M M (NW/VIM i7. A @L . (chm/Lace I , MM MW 6 WW 4 {W MW (mm m A (zwtlififmw [Mfg Maggi” 21. ABO blood types in humans are determined by a single gene h’avmg three alleles, h 0"” . ' 7! 1'4, [8. and 1'. WM “MW ‘ (i) A mother with blood type B has a c ' possible genotypes of the fa with blood type 0. What are all \ 13L 1“ t a L Ki (ii) The alleles for the ABO blood type gene exhibit 22. Flower color in the plant blue-eyed Many (Ci/linsia parviflora) is governed by two \\ _VJ LNS flmfi (ii) Using your own symbols, show the genotypes associated with the three ' l . h ' “ phenotypic c asses MM] Pk H ‘ Wjam’m '5 B “U W 4 Mpg/r tom 3 M- -, 10/9 WMth 1 m/m‘} 8/~ whit Mil/M a i am 7 to b Wm mummy? Q3) Most pedigrees show polydactyly to be inherited as a rare autosomal dominant trait. However, the pedigrees of some families do nomly conform to the patterns expected for such inheritance. Such a pedigree is shown below. Based on this pedigree, what conclusion can you derive regarding the inheritance of this trait? / M\ mm M Q! vfwmhaw ‘flwM/mt k M 31/3 0% + M“ WM amt/0U AA w A UTE/Am I A. Wk ngb’lfi/‘tlfld’ i8 UNI mam (UU/U' AA AA, , . 1' WhWW’l/‘al/ég—“o/fi mom/WW” wvu WM W (Law 6mm mam W film W W To determine the number of genes involved in leg coordination in Drosophila {Kw/{fl ’ melanogasler. mutant flies showing abnormal leg coordination were identified. Four homozygous recessive mutant lines (labeled 1 through 4) were intercrossed in a complementation test and the following results were obtained. In the table, (+) represents progeny flies with wild-type leg coordination and (-') represents progeny flies with abnormal leg coordination. .u’J ‘ [3 ON flat} 1 z 3 4 1= '1 Wt“) Aim/U 1 - f l + + g “kg 3 2 + - - + WKYW‘“ (/ 3 + - - + 4 + + + - (i) Organize the mutants into c ., plementation groups. 67m fl : 3— 5W. , : 7,473 firm/«V % : Li ’ (ii) Based on the mutants analyzed, at a mi ' tum how ny genes in Drosophila melanogaster are invol in leg coordin tion‘? /. ...
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This note was uploaded on 03/20/2008 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas.

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BIO325 exam1 2007 - Twit/(my Wm THC UQ $ GENETICS (BIO...

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