Nutrition andGene Expression

Homework assignmentson mutations

Feb 6, 2014

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 differentfrom sequence #1. What is the product in each case?

-How would the biochemical properties of each productbe different, when compared to sequence #1?

(You will need to use the table of codons, to determine whichamino acid is incorporated into each product. You will then needto examine the table of amino acid side chains, to determine theproperties of each peptide).

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

GCA-UUC-GAA-CUC-AAG-AUG-UAC-AGCGCA-UUC-GAA-CUC-AAG-AUG-UAC-AGC

The top strand is the original sequence for the RNA. The changed RNA CODON is underlined, for each mutation.

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

AUAUGCUACAGCGCAUAU

New protein

Problems: Frequency of the appearance of recessive traits in offspring (child inherits the recessive gene from both parents).

G G G G GGr G G G G

B B B Br BB B B B B

In this case, the probability that Gr x Br will have a child,is given by 0.1 x 0.1 = 0.01.

These two populations of females and males eachhave 10% occurrence of a recessive trait. In thefollowing calculations, assume EQUAL PROBABILITYthat any female, and any male, will have a child together.

Example 1. The occurrence of the recessive trait withina 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 withina 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 withina 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 MARRIAGEOCCURS BETWEEN POPULATIONS WITH DIFFERENT FREQUENCIESOF THE RECESSIVE TRAIT THAT WE ARE CONSIDERING

G G G G GGr G G G GG G G G GG G G G GG G G G G

B B B Br BBr B B B BB Br B B BBr B B B BB B Br 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.

Example 4. The occurrence of the recessive trait withinPOPULATION 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?

MARRIAGES BETWEEN FEMALES AND MALES BETWEENTWO POPULATIONS, WHERE FREQUENCY OF SHARED RECESSIVE TRAITS IS VERY DIFFERENT BETWEEN THE POPULATIONS.

Example 5. The occurrence of the recessive trait withinPOPULATION 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?