1. Use the following info to answer part a) to d) Part A A normal chromosome (al
ID: 64434 • Letter: 1
Question
1. Use the following info to answer part a) to d)
Part A
A normal chromosome (all caps) and its homolog (all lower-case) carrying a mutation are shown below. The dot represents the centromere (the all caps and all lower case versions are just used to differentiate between the two different homologs and do not represent dominant or recessive versions of the genes in this example):
Normal: ABC•DEFGHIJK
Mutant: abc•dhgfeijk
a) What type of gross chromosomal mutation is present in this individual?
Options:
a
Non-reciprocal translocation
b
Reciprocal translocation
c
Deletion
d
Insertion
e
Pericentric inversion
f
Paracentric inversion
b) If a crossover occurs between genes “B” and “C” what proportion of the gametes will be viable?
options:
a
0% viable
b
25% viable
c
50% viable
d
75% viable
e
100% viable
c) If a crossover occurs between genes “F” and “G” what proportion of the gametes will be viable?
Options:
a
0% viable
b
25% viable
c
50% viable
d
75% viable
e
100% viable
d) If a crossover occurs between genes “F” and “G” what is the sequence of the acentric fragment that is produced?
Format: text only corresponding to the genes on the chromosome eg. ABFGIJK
Part B: Use the following to answer part e) to g)
A common mutation associated with Sickle Cell Anemia is a Glu6Val mutation (this shows that amino acid #6 is Glu in wild type individuals and Val in individuals with the Sickle Cell allele).
e) Would you characterize this mutation as silent, missense or nonsense at the amino acid level?
options:
a
Silent
b
Missense
c
Nonsense
f) Do the amino acids Glutamic acid and Valine share similar R-groups? How might these differences affect hemoglobin function?
g) Which type of mutation at the DNA level likely caused this change from Glu to Val?
options:
a
base substitution, transition
b
base substitution, transversion
c
deletion
d
insertion
a
Non-reciprocal translocation
b
Reciprocal translocation
c
Deletion
d
Insertion
e
Pericentric inversion
f
Paracentric inversion
Explanation / Answer
a) The mutation is paracentric type as one arm of chromosome underwent some with the arrangement of genes.
b)50% of the gametes would be viable.
c) 50% of the gametes would be viable.
d)If a crossover occurs between genes “F” and “G” then the sequence of acentric fragment would be ABC•DEGFHIJK.
e) Sickle cell anemia involves the substitution of Glu to Valine which shows missense type of mutation.
f) No, Glutamic acid and Valine do not have similar R-group. The substituted amino acid i.e. valine causes the hemoglobin to distort to a sickle shape when deoxygenated as the polar amino is replaced by a nonpolar group.
g) The mutation involved is transition mutation as it involves the conversion of G-C to A-T.
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