BIO325 exam1 2006 - 6 1 Exam SUMMER 2006 Total points:...

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Unformatted text preview: 6 1 Exam SUMMER 2006 Total points: 120‘ 4 / \ GENETICS (BIO S325) 7/19/06 There are 24 questions in this exam. Each question carries 5 points. Answer all 24 questions for a maximum of 120 points. Select ONE answer in questions with multiple choices. 1. Leg] CIZXVZV"zY‘QYVeV’ffvflVi23(V2\<i/2\ 2. 3f The allele c causes albinism in mice (C causes mice to be black). If the cross C/c x c/c is made, and there are 10 progeny, what is the probability that all the / progeny will be black? L C @2 cc”;- C‘ Cc (c In a diploid organism with 2n = 6, there are two long, two intermediate, and two short chromosomes. Which one of the following is the most accurate representation of a gamete resulting fro meiofi in this organism? =——< (a) “C X 120:2): In moss, the genes A and B are expressed only in the gametophyte. A sporophyte of genotype A/a,: B/b is allowed to produce gametophytes. . . . t r i . “l (1) What proportion of the gametophytes Will be A; B? c“ b t > e " H; . ‘ ‘/L/ 1' ‘ “ . (ii) If fertilization 1s random, what proportion of sporohytes in the next generation will be A/a; B/b? '44 {m ( (AM My 4. Answer if the following statements are true or false: (a) Homologous chromoso es carry alleles for the same genes in the same ' r _ relative positions. Trved ' (b) Homologous chro osomes regularly exchange parts by crossing over at meiosis. T‘W 7 g (c) Homologous chromosomes physically pair at mitosis. Arnke/ (d) Homologous chromosomes are found in pairs but they do not physically pair in interphase in a diploid cell. pave] (e) Homologous chromosomes duplicate before entering prophase of mitosis such, that each chromosome has two chromatids. Rug, 5. 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 females. Assuming there is a single father for the litter, what is his probable color? YC‘XC X X Y )(CXc-FQ M 7 ~ eeeee 5313?}75375%3 ><asxcxciiaw Maw l/ *X . X Y ‘ l I'/Ll lyi‘a'? wail» l/q (wt/(4 . ’I/U mellow “Li 'A,‘ (ii) A yellow cat has a litter of four kittens: 1 yellow and 3 calico. Assuming there is a single father for the litter, what is the probable sex of the yellow kitten? Xg \( L r ,i ' ,{ IN a l/ - . XC’ / )(CYC‘. X 7/, MKC— -‘ V i .C y 17:...4" r I." 6. (i) In a plant in which 2n = 24, what is the total number of chromatids present during prophase I of meiosis? / (ii) In a plant in which 2n = 24, what is the total number of chromatids present during prophase of mitosis? m : q (S (i) Identify the most likely mode of inheritance (autosomal dominant, autosomal recessive, X-linlgeddominant, X-linlgedrecessive, Y-linked, cytoplasmic) for the following pedigree. ' V A a“ (ii) What is the probability that individuals Ill-1 and 111—4 will have an affected child if they decide to get married? 1/5, t Y \ /. Kb , (i) Indicate whether the following statements are true or false. flag (a) The DNA of a eukaryotic chromosome is one long double helix. \ " (b) A centromere is always in the middle of a eukaryotic chromoso . ABC (c) A telomere is always on the end of a eukaryot' chromosome. T «‘1 ‘31 (d) Histories are rich in‘basic amino acids. ’M _ / (e) Each eukaryotic chromosome has multiple origins of replication. Xm’fl, (ii) A nucleosome is composed of DNA and histones. Mention the histones present in the nucleosome and the ratio in which they occur. 42A ‘ VU‘ HZ?) : ‘H W; : Va M r (i) Which of the following is the correct order of increasing levels of chromosome packing (smallest to largest)? (a) Nucleosomes-loops-solenoid-supercoils M Solenoid-nucleosomes—loops-supercoils Solenoid-nucleosomes-supercoils-loops V Nucleosomes-solenoid—loops-supercoils ,(e’) Solenoid-loops-nucleosomes-supercoils (ii) The central scaffold a) Is found only in prokaryotes ® Is largely composed of the enzyme topoisomerase ll (c) Is the site where DNA polymerase binds (d) Is the attachment site for centromeric microtubuies (e) ls made up histone proteins 3 10. Tall, yellow-flowered crocus is mated with short, white-flowered crocus. Both varieties are true breeding. All the F 1 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 1:1 :1 :1 segregation. (i) Determine the chi-square value form the giyzén data. 3 . 8 ‘1 _ (ii) What are the degrees of freedom in thisfxample? '* (iii) Determine the approximate probability (P value) from the given table. 6 2W 0 . 5’ «NA 0 _\ (iv) Based on the P value, is the hypotheéis accepted or rejected? Accéf 1 Z . K : 1 o e ’ / (M o e (mes (go, (.915. l,”— . - 3‘45 TRKK \(c 11% 1W1 20% 61 81 g - » 1 '5 tau wk‘Kc 27/5 log ‘2 5201 ‘ a“ KKK” mg 20S -10 \oo o "154‘g gm amt: (W 205 —\'1 zen 3411. . —:/‘ f 4520 $20 3 «(6’1 Table 2-2 ('z'itix'aI \"aluox 0111110 ,\' Distribution P (11‘ 0.995 0.5175 0.0 0.5 0.1 0.05 0.025 0.01 0.005 1 .000 .000 0.016 0.455 2.706 3.841 5.024 6.635 7.879 2 0.010 0.051 0.211 1.386 4.605 5.991 7.378 0.210 10.597 3 0.072 0.216 0.584 [2.366 6.251 ‘ 7.815. 9.348 11.345 12.838 4 0.207 0.484 1.064 3.357 7.771 9.488 11.143 13.277 14.860 5 0.412 0.831 1.610 4.351 9.236 11.070 12.832 15.086 16.750 6 0.676 1.237 2.204 5.348 10.645 12.592 14.449 16.812 18.548 7 0.989 1.690 2.833 6.346 12.017 14.067 16.013 18.475 20.278 8 1.344 2.180 3.490 7.344 13.362 15.507 17.535 20.000 21.955 9 1.735 2700 4.168 8.343 14.684 1691‘:1 19.023 21.666 23.589 10 2.156 3.247 r 4.865 9.342 15.987 18.307 20.483 23.209 25.188 11 2.603 3.816 5.578 10.341 17.275 19.675 21.020 24.725 26.757 12 3.074 4.404 6.304 11.340 18.545) 21.026 23.337 26.217 28.300 13 3.565 5.009 7.042 12.340 19.812 22.362 24.736 27.688 29.819 14 4.075 5.629 7.790 13.339 21.064 23.685 26.119 29.141 31.319 15 4.601 6,262 8.547 14.339 22.307 24.996 27.488 30.578 32.801 (11 ‘JVJKDJNH \10‘ 15% ll 12 13 14 15 5 N igékw‘hal WWMHW of their first child having Tay-Sachs disease? 3 ’ ‘1" 0\/Y(7\ p 12. 13. fiffi * A couple without an ancestral histo ' of Tay-Sachs disease (an autosomal recessive) have two normal children and an infant affected with Tay-Sachs. The sister of the husband wants to marry the brother of the wife; in such a mating, ‘ F‘l‘l N“ ‘ L l . 6" x— L F r: fixéflfLaxQ Z 2 :1‘ . H Al .‘ lg L’l [‘0 w ; h d m d f 1 h h £11" F51“ H0 M A uman iseasea icte a amiyass own int e o owin ei ree. "2a.,a t/J—g—bg h t ‘ O I a A t X a x Y N“ I A I O O O O O I I L I Xc\ O O 1 O I I I I I ‘ O I What is the most likely mode of inheritance of this disease? 667K—\ Mach Am Wank The maize genes sh and bz are linked and are 40 map units apart. If a plant with the genotype is sh+ bz / 5/1 [72’ is testcrossed, what proportion of the progeny will have the genotype: Y 5h k? Hr Z (i) sh bz/sh bz %bT?_ P.- with? o L w a D“ W I. S a? J 3 9" a; ‘Tflfj (100/6 (gig \[2 ; gin - ‘W'; (ii) sh+ bz/sh bz 51? 7 c/O ” ’ ‘ 055 o o lfl:ff0 /(/ (l’L’l‘O kl 14. For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. f7 fl ,—_ An organism that has five homologous pairs 16f chromosomes can produce, in t genetically possible. 5 8 10 15. absence of recombination, fferent types of gametes. Recombination will MIA-Case, the number of genetically different gametes 15 25 32 3?. decrease increase $6 A trihybrid cross is a cross between two individuals who are heterozygous for three genes. For example: A/a - B/b - C/c x A/a - B/b - C/c. Assuming these three genes are unlinked and assorting independently, what phenotypic ratio would be observed in the offspring resulting from this cross? W (b)lilili1 .4 ' 16:9:9:3:3:1 27:9:9:9:3:3:3:1 ) 12:9:3zl H ‘70 enotype B r/b r? p: \ggvlo‘i/j (1 1 B v ’V \01“ 7 V2 400 A trihybrid corn plant of genotype A/a ° B/b ° C/c (order of genes is not known 18 A fruit fly of genotype B [Vb r is crossed to a fly with the genotype b r/b r. In 84" percent of the meioses, there are no chiasmata between the linked genes; in 16 percent of the meioses, there is one chiasma between the linked genes. What 6 proportion of the progeny from this cross will have the g F E) 1 r v . testcrossed. The trihybrid produces gametes with the following phenotypes and .09; A :— :’ 16% t Z W V 17. frequencies CAB 7% ABC bm‘o ’10 abc C m?) Hfil _ aBC CAM» 50 “5‘20 Abc c. Id "34010 ABC C o\\: 2 abc C “5 (5‘3 ch c ms 583’ MC 74 70 44 50 3] We 368 3% 1000 19 (i) Determine the order of enes. g 6A0 lama (ii) Calculate the map diétance for the adjacent gcggb Lg C {£2 fl A60 Eflwc Y2: t, AC, \WC m /:7 B 6/16 7-- m 15 C, f3. cg / / f f or i /flc /".t5 .IlA H03 221 M [‘\ Pb : 18. In Neurospora, a linear biochemical pathway synthesizes an amino acid Z. V% E 1, 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 with compounds ‘ ‘ or X (3‘ (N (6» Y or z (c) WorXorYorZ (d) Z only (e) W only 6 19. Based on their studies in Neurospora, Beadle and Tatum proposed the one-gene— one-enzyme hypothesis. Explain why it is more accurate to call it the one-gene- one—polypeptide hypothesis. A 03% (,pv- mkucixw cock Ca» mew; M 0% park'th 1111 WWW, W17 14%? 63¢, Ill/1611 NW em 0 all 01. W} f A rare. curly-winged mutant of Drosophila was found in nature. A mating of this fly with a true-breeding, normal laboratory stock produced progeny in the ratio 1 curly-winged to 1 normal (both sexes had the same ratio). All curly-winged \ progeny of this cross, mated with normal progeny of the same cross, again yielded \ ' 1 curly-winged to 1 normal fly. When mated with one another, the curly-winged B ,, \ progeny of the first cross yield a progeny of 623 curlyz323 normal. This ratio "1 ' strongly suggests which of the following: (a) Curly and normal are in the 3:1 ratio expected from intercrossing monohybrid genotypes for a recessive mutant allele (curly). (b) Curly and normal are in the 3:1 ratio expected from intercrossing V monohybrid genotypes for a dominant mutant allele (curly). (9) The curly-winged parent of the curly x curly cross is homozygous. 4/85 The curly allele is lethal in the homozygous state and flies homozygous for the curly allele never survive. 21. In maize, two plants that are both heterozygous for the recessive alleles a and b are crossed. What frequency of double-mutant progeny (a b/a_b) will appear if a and b are 7.2 map units apart, and both parents are dihybrids in the trans), 1, 6 configuration? /0\% X A \p /O\ L tam». _ T/ 7‘ if; IUll/Z (I p: w ’7 a)“ 7 Tl ‘ 3: 7; r‘, 1 Vii _' 14 @’V M ‘y/ [0739 N639 23. 6 TL: \4~ 24. Indicate whether the following statements are true or false. (a) The smaller the proportipé/of recombinants in the progeny. the tighter the linkage of genes. Try (b) The maximum recombination between two loci on a single chromosome is 50% because only two of the fou associated chromatids participate in an A, individual recombination event. Fox ‘ 17 “Al 2 i __._, (c) Pleiotropism is the situation in w 'ch 3 gene affects two or more unrelated aspects of a phenotype. Twé I / (d) For X-linked dominant traits, affected sons always h 6 affected mothersfl Wee, (e) A dihybrid genotype is represented as A/B; a/b. Fakgp if ‘ ‘ mm,- g/ L, )Z’flr to Z O . . A segment of map a ----- --b ----------- --c 15 shown. where the distance between a («it and b is 10 map units, and the distance between b and c is 20 map units. With 0% interference, what would be the observed frequency of double crossovers? abscwedeCG L‘A \hww expected DCQ ('l 7‘ '2» fr ABO blood types in humans are determined by a single gene having three alleles, l4, [8, and i. (i) A mother with blood type A has a child with blood type 0. What is the mother’s genotype? t/t \ 14/]; 1A/ (ii) A mother with blood type B has a child with blood type 0. What are all possible genotypes of the father? I” / L/L) 1/» Ill/q 18/ L A (iii) A woman of blood type AB marries a man of blood type AB. What blood types are possible among their children? IA/IB x iA/I‘g l’WP IRE/AB ‘ Thealleles for the ABO blood type gene exhibit (a) complete dominance only M 0) incomplete dominance only co-dominance only both dominance and co-dominance ...
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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 at Austin.

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BIO325 exam1 2006 - 6 1 Exam SUMMER 2006 Total points:...

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