In goldfish normal (gold, G) scales are dominant to white scales (g): Short fins

ID: 282578 • Letter: I

Question

In goldfish normal (gold, G) scales are dominant to white scales (g): Short fins (F) are dominant to long, fancy fins (f). A true breeding gold-scaled fish with fancy fins is mated with a true breeding white scaled fish with short fins. The F1 progeny are crossed with a testcross individual. It is known that the G and F genes are lined and 12 map units apart. 1. Write out the genotypes of the following individuals, as they would appear on chromosomes: a. i. true breeding gold scaled fish with fancy fins: ii. true breeding white scaled fish with short fins: iii. F1 progeny: b. What is the genotype of the testcross parent (written on chromosomes? List the different gamete(s) produced by the testcross parent. c. For each progeny type, state if they are a recombinant or no recombinant (parental) progeny and what percentage of the progeny they should make up. Progeny Phenotype Non-recombinant or recombinant % of progeny gold scaled fish with fancy fins white scaled fish with fancy fins gold scaled fish with short fins white scaled fish with short fins

Explanation / Answer

a).

GGff x ggFF -----Parents

Gf / gF -------------F1

i). True breeding gold scaled fish with fance fins = GGff

ii). True breeding white scaled fish with short fins = ggFF

iii). F1 progeny = Gf / gF

b).

Gf / gF x gf / gf (test cross parent) -------------Test cross

Only one type of gametes are produced from test cross parents & its genotype is gf.

Map unit distance = Recombination frequency (%)

Gf(44%)

Gf / gf (44%) ---Non-recombinant

gF (44%)

gF/gf (44%) –Non-recombinant

GF(6%)

GF/gf (6%)---Recombinant

gf(6%)

Gf/gf (6%)—Recombinat

c).

Progeny pheontype

Non-recombinant or recombinant

% of progeny

Gold scaled fish with fancy fins

Non-recombinant

44%

White scaled fish with fancy fins

Recombinat

Gold scaled fish with short fins

Recombinant

White scaled fish with short fins