Answer Correct Genetic Linkage & Mapping Flashcards

Suppose a three-point testcross was conducted involving the genes A, B, and C. If the most abundant classes are CaB and cAb and the rarest classes are cab and CAB, which gene is in the middle?

The tendency of genes to be transmitted together exemplifies __________ and a unit of genetic map distance is called a __________.

In humans, the genes for red-green color blindness (R=normal, r=color-blind) and hemophilia A (H=normal, h=hemophilia) are both X-linked and only 3 map units apart. Suppose a woman has four sons, and two are colorblind and have hemophilia and two are normal. What is the probable genotype of the woman?

In Drosophila, singed bristles (sn) and cut wings (ct) are both caused by recessive, X-linked alleles. The wild type alleles (sn+ and ct+) are responsible for straight bristles and intact wings, respectively. A female homozygous for sn and ct+ is crossed to a sn+ct male. The F1 flies are interbred. The F2 males are distributed as follows: genotype number sn ct 15 sn ct+ 34 sn+ ct 33 sn+ ct+ 18 What is the map distance between sn and ct?

The Q and P genes are linked and 20 map units apart. In the cross Qp/qP x qp/qp what fraction of the progeny will be QP/qp?

The map of a chromosome interval is X 5 Y 10 Z. From the cross Xyz/xYZ x xyz/xyz, how many double crossovers would be expected out of 1000 progeny?

If the map distance between genes A and B is 15 map units and the map distance between genes B and C is 40 map units, what is the map distance between genes A and C?

The measured distance between genes D and E in a two point test cross is 50 map units. What does this mean in physical terms?

In tetrad analysis, NPD asci result from:

A wild-type yeast strain is crossed with another strain that is auxotrophic for both arginine and uracil (needs both arginine and uracil added to medium to grow). The resulting heterozygous diploid cells are allowed to undergo meiosis and the products of meiosis are analyzed. There are three classes of unordered tetrads observed: Class one: 2 spores that fail to grow without arginine and uracil (125 tetrads) 2 wild-type spores Class two: 2 spores that fail to grow without arginine, but can grow without uracil (5 tetrads) 2 spores that fail to grow without uracil, but can grow without arginine Class three: 1 spore that fails to grow without arginine and uracil (70 tetrads) 1 wild-type spore 1 spore that fails to grow without arginine, but can grow without uracil 1 spore that fails to grow without uracil, but can grow without arginine What is the map distance between the arg and ura genes?

An underlying assumption about linkage can be given by __________ and a statistical test of linkage is called __________.

Determine which gene is in the middle for each of the three experiments in the table below. Experiment Gametes produced from heterozygote A B C + + + 303 1 41 + + c 61 3 232 + b + 11 29 82 + b c 3 75 201 a + + 1 77 194 a + c 19 31 77 a b + 72 4 235 a b c 253 1 46

A true-breeding wild-type female fly is crossed to a true-breeding ebony male with vestigial wings and cardinal eyes. All traits are autosomal recessive. The resulting heterozygotes are testcrossed and the frequencies of the phenotypes are shown in the table below. Draw a linkage map of the three genes. eye color body color wings number cardinal ebony vestigial 245 red tan normal 241 cardinal ebony normal 235 red tan vestigial 225 cardinal tan vestigial 10 red ebony normal 14 cardinal tan normal 14 red ebony vestigial 16 Total 1000 What is the order of and map distance between the three genes?

In Drosophila, the genes A, B, and C are linked and in the order given. The distances are A-B = 5 m.u. and B-C = 15 m.u. The interval exhibits 20% interference. How many double crossovers would be recovered in a three-point cross involving A, B, and C out of 500 progeny?

A trihybrid (3 genes heterozygous) produces the following gametes: ABC 46 Abc 63 ABc 4 aBc 381 abc 38 aBC 71 abC 2 AbC 395 total 1000 What is the order of and map distance between the three genes?