Download 2) Homework

Nutrition and
Gene Expression
Homework assignments
on mutations
Feb 5, 2015
THE CONSEQUENCES OF MUTATIONS:
Homework assignment
How is each mRNA sequence translated?
For each 24-base mRNA sequence, predict how it will be
translated by the ribosomes.
-For each sequence, there is a SINGLE base that is different
from sequence #1. What is the product in each case?
-How would the biochemical properties of each product
be different, when compared to sequence #1?
(You will need to use the table of codons, to determine which
amino acid is incorporated into each product. You will then need
to examine the table of amino acid side chains, to determine the
properties of each peptide).
The top strand is the original sequence for the RNA. The
changed RNA CODON is underlined, for each mutation.
GCA-UUC-GAA-CUA-AAG-AUG-UAC-AGC
GCA-UUC-GAA-CUC-AAG-AUG-UAC-AGC
GCA-UUC-GAA-AUC-AAG-AUG-UAC-AGC
GCA-UUC-GUA-CUA-AAG-AUG-UAC-AGC
GCA-UUC-GAA-CUA-UAG-AUG-UAC-AGC
AUAUGCUACAGCGCAUAU
What protein could this very short sequence of RNA
produce? For that you need to review the genetic code:
AUA-UGC-UAC-AGC-GCA-UAU
Ile - Cys - Tyr - Ser - Ala- Tyr
New protein
Problems: Frequency of the appearance of recessive traits in
offspring (child inherits the recessive gene from both parents).
G G G G G
Gr G G G G
B B B Br B
B B B B B
These two populations of females and males each
have 10% occurrence of a recessive trait. In the
following calculations, assume EQUAL PROBABILITY
that any female, and any male, will have a child together.
In this case, the probability that Gr x Br will have a child,
is given by 0.1 x 0.1 = 0.01.
Example 1. The occurrence of the recessive trait within
a population is 0.2.
-what it the likelihood of a marriage between Gr and Br?
-what is the likelihood of a the full recessive in the child?
Example 2. The occurrence of the recessive trait within
a population is 0.05.
-what it the likelihood of a marriage between Gr and Br?
-what is the likelihood of a the full recessive in the child?
Example 3. The occurrence of the recessive trait within
a population is 0.01.
-what it the likelihood of a marriage between Gr and Br?
-what is the likelihood of a the full recessive in the child?
THE NEXT PROBLEMS CONCERN SITUATIONS WHERE MARRIAGE
OCCURS BETWEEN POPULATIONS WITH DIFFERENT FREQUENCIES
OF THE RECESSIVE TRAIT THAT WE ARE CONSIDERING
G G
Gr G
G G
G G
G G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
B B B Br
Br B B B
B Br B B
Br B B B
B B Br B
B
B
B
B
B
In this case, the probability that Gr x Br will have a child,
is given by 0.04 x 0.2 = 0.008.
MARRIAGES BETWEEN FEMALES AND MALES BETWEEN
TWO POPULATIONS, WHERE FREQUENCY OF SHARED RECESSIVE
TRAITS IS VERY DIFFERENT BETWEEN THE POPULATIONS.
Example 4. The occurrence of the recessive trait within
POPULATION A is 0.2 AND POPULATION B IS 0.01.
-what it the likelihood of a marriage between Gr and Br?
-what is the likelihood of a the full recessive in the child?
Example 5. The occurrence of the recessive trait within
POPULATION A is 0.5 AND POPULATION B IS 0.001.
-what it the likelihood of a marriage between Gr and Br?
-what is the likelihood of a the full recessive in the child?