I need help in this genetic problem questions. its 2 qeustion only pleas help me
BIO340
Problem Set 7
Due May 3rd at 11:59pm
** Please TYPE your answers in BLACK TEXT in the space after the question**
*Save your completed homework as a PDF and upload the PDF to blackboard*
1) Look at the key for the previous problem set. Identify one question you got wrong and
explain why you got it wrong and what the right answer is. If you didn’t get a question wrong,
which question do you think was the hardest and why? (1pt)
2) Why is the frequency of recombinant gametes always half the frequency of crossing over?
(5pts)
3) In maize plants, large kernel size (k) is recessive to small kernel size (k+), yellow kernel color
(y) is recessive to red kernel color (y+), and long cobs (c) is recessive to small cob (c+) The genes
encoding these phenotypes are linked, with the following cM between them. (24pts total)
6
13
a) what are the genotypes/phenotypes and frequencies of the offspring of a triple homozygous
mutant corn crossed with a triple homozygous wildtype corn. Explain your answer (4pts).
b) The offspring from part a is used in a testcross. What are the genotypes/phenotypes and
frequencies of the offspring from this test cross? Explain your answer (10pts).
c) In a separate cross, a triple heterozygous mutant with the c+ allele in trans to the other
wildtype alleles is crossed to a triple homozygous mutant fly. What are the
genotypes/phenotypes and frequencies of the offspring from this test cross? Explain your
answer (10pts).
3) In the nematode C. elegans, there are many phenotypes due to recessive alleles, three of
which are shown in the picture below (25pts total)
BIO340
Problem Set 7
Due May 3rd at 11:59pm
Dpy (dumpy) worms are short
and fat (dpy+ is the wt allele
and dpy is the mutant).
Rol (rolling) worms display a Ushaped body and cannot move
in a strait line (rol+ is the wt
allele and rol is the mutant).
Muv (mutli-vulva) worms
display multiple non-functional
vulvas (arrowheads) and can
have problems laying eggs
(muv+ is wt allele and muv is
the mutant).
a) The genes encoding these three phenotypes are linked. What are the genotypes/phenotypes
and frequencies of the offspring of a triple homozygous mutant worm crossed with a triple
homozygous wildtype worm? Explain your answer (3pts).
b) A test cross is performed using the worms made in part a. The results are shown in the table
below. what is the order of the genes on the chromosome? Explain your answer (10pt)
Progeny Phenotype
Number
All WT
274
All mutant
320
Muv only
57
Dpy and Rol
45
Muv and Dpy
6
Rol only
5
Muv and Rol
0
Dpy only
1
Total
708
c) in the empty column, describe the recombination event (No CO, CO1, CO2 or 2xCO) that gave
rise to the offspring phenotype in each row. (8 pts)
d) What is the cM between each gene? (4pts)
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