Download Genetics Exam: Phenotype, Genotype, Orthologs, Chromatin, Mitotic Spindle, and Probability and more Exams Medical Microbiology in PDF only on Docsity! Name_________________________________________ Genetics Exam #1 October 6, 2004 (5)Define and distinguish between phenotype and genotype. phenotype are the observable characteristics of the organism genotype is the combination of alleles an organism has (5)Define and distinguish between heterochromatin and euchromatin. heterochromatin is gene sparse regions near the telomeres and centromeres euchromatin is the extended, gene dense regions of the chromosomes (3)Define ortholog. homologous gene in a different organism which performs the same function (3)Define Robertsonian translocation. fusion of 1 chromosome with another, giving an abnormal karyotype (3)Define mitotic spindle. series of microtubules which pull apart the chromosomes during mitosis (3)Define pachytene. stage of meosis where homologous chromosomes line up and crossover events occur (3)Define nucleosome. unit of DNA organisation with DNA wrapped around a group of 8 histone proteins (3)Define chromosomal inversion. when a series of genes on the chromosome invert their order ie. abcedf becomes adecbf. (3)Define karyotype. ordered presentation of metaphase chromosomes grouping chromosomes by size (3)What is the probability of having 4 girls of 6 kids? Show your reasoning. by binomial formula, 6!/(4!2!)* (.5)2(.5)4 = 30/2*1/64 = 15/64 by Pascal's triange, coefficient is 15, 26=64 possibilities, so 15/64 (6)You are a plant breeder trying to obtain the perfect rose. If you cross AaBBccDd x aaBbCcDd what is the probability of obtaining a aaBBccDD individual in the F1 generation? 1/2 * 1/2 * 1.2 * 1/4 = 1/32 what is the probability of obtaining a AabbCcDd individual in the F1 generation? 1/2 * 0 * 1/2 * 1/2 = 0 (10)In fruit flies, 6 genes a,b,c,d,e, and f are in the region of polytene band 16.5. 4 deletions are known to occur in this region: #1 deletion for a, b, and e #2 deletion for c and e #3 deletion for b, d, and f #4 deletion for a, b, and d What is the order of genes on the chromosome? a,b,e are together. c and e are together. b,d,f are together. a,b,d are together. (a b e) e c (d f) b d b a f d b a e c OR c e a b d f (10)You cross a red, single flower true breeding snapdragon to a white, clustered flower truebreeding snapdragon. All of the offspring in the F1 generation are pink, single flowered individuals. Using R to represent red, r to represent white, F to represent single flower and f to represent clustered flowers, what are the ratios and phenotypes obtained in a self cross within the F1 generation? pink, single flower = RrFf heterozygote since parents were true breeding ie RRFF and rrff RF Rf rF rf RF RRFF RRFf RrFF RrFf Rf RRFf RRff RrFF Rrff rF RrFF RrFf rrFF rrFf rf RrFf Rrff rrFf rrff 3 red single, 1 red cluster 6 pink single, 2 pink cluster 3 white single, 1 white cluster 1:2:1 red:pink:white, 3:1 single:clustered Degrees
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