Name ___________________
PID ___________________
Section (circle):
1- Karen
2- Robyn
3- Veronica
CSS 350
Homework Assignment 7 (corrected version)
Assigned 2/2/01
Due 2/16/01
Assume Mendel’s seed shape (alleles=R or r, R_= round,
rr=wrinkled) and seed color (alleles=Y or y, Y_=yellow,
yy=green)are linked and 10 map units apart. The R locus is 20 map
units from the centromere, and the Y locus is 30 map units from
the centromere.
1)
What frequency of cells undergoing meiosis are expected to
have a cross over between the R and Y loci?
2)
What frequency of gametes are expected to be recombinant
from a dihybrid for these genes?
Create a drawing of metaphase in mitosis for plants with the
following genotypes or phenotypes(your drawings will only
include the chromosome(s) with the R and Y loci):
3)
rryy
4)
RRYY
5)
rrYY
6)
RRyy
7)
the F1 from a cross of rryy and RRYY
8)
the F1 from a cross of RRyy and rrYY
9)
the F1 from a cross of rrYY and RRyy
10) the F1 from a cross of RRyy and RRYY
11) Ry/rY
Name ___________________
PID ___________________
Section (circle):
1- Karen
2- Robyn
3- Veronica
12) a seed that is green and wrinkled
Draw Metaphase I, Metaphase II, and the four meiotic products
for the following genotypes (assume any crossovers involve only
1 chromatid from each homolog:
13) Ry/rY with no crossovers
14) Ry/rY with a crossover between the centromere and the R
locus.
15) Ry/rY with a cross over between the R and Y loci.
Write the frequency distribution of gametic genotypes expected
from these genotypes (include the decimal frequency and the
gametic genotype)
16) Ry/rY
17) ry/RY
18) RY/Ry
[NOTE: the following background information was wrong in the
version handed out in class 3/2/01. That version described a
test cross of a plant from a green, round seed. This also
affected question 22]
Assume you do not know the linkage arrangement of the R and Y
genes. A testcross of a plant grown from a Yellow, round seed
has the following progeny:
Phenotype
number of progeny
Green, Round
222
Green, Wrinkled
280
Yellow, Round
280
Yellow, Wrinkled
218
total 1000
19) What are the expected numbers for the test cross progeny
phenotypic classes if R and Y are not linked?
Name ___________________
PID ___________________
Section (circle):
1- Karen
2- Robyn
3- Veronica
20) Calculate X2 to test the hypothesis that R and Y are linked
given the data above. Show all work including the degrees
of freedom and the p value.
21) State what the p value means from question 20.
22) Assuming the genes are linked, draw the two chromosomes of
this homologous pair in metaphase of mitosis of the plant
that was tested (the one from the yellow,round seed). Label
the loci with the alleles on each chromatid, and indicate
the distance between the loci in centimorgans.