Question

1) Design a set of 6 base pair long primers that scientists could use to amplify the entire sequence of the gene in Q11 from the coronavirus genome. Be sure to label the 5' and 3' ends of your primers!

2) Unverricht-Lundborg disease is caused by an increased number of copies (expansion) of the dodecamer repeat in the CSTB gene on chromosome 21. Most people with this disorder have more than 30 repeats of the dodecamer sequence in both copies of the CSTB gene. Neither Pam or her partner Rick have Unverricht-Lundborg disease but their child Oscar has both Down syndrome and Unverricht-Lundborg disease. Primers specific to the CSTB gene are used in a PCR reaction to genotype all three family members by geneticists curious about the origin of the two disorders. The results obtained by gel electrophoresis indicate that the nondisjunction event occurred in Pam.

On the diagram draw the results that support this conclusion.

3)The spike protein on the surface of SARS-CoV-2 virus particles interacts with the ACE2 protein on our cells to initiate infection. The protein, TMPRSS2, then cleaves the spike protein allowing the virus to enter the cell. This leads to both cell death via pyroptosis and a widespread inflammatory response that damages the lung infrastructure.

Scientists have identified a mutation in the TMPRSS2 gene that reduces viral entry in mice. Infected cells with the tmprss2 mutation make TMPRSS2 protein that is unable to cleave the spike protein. Based on this information the mutation is most likely:

• A.

  loss of function

• B.

  null

• C.

  gain of function

Answer 1

1.- (You forgot to provide the gene sequence)

2.- Okay, if their child has the disease, it means both parents are carriers, each one of them has a CSTB gene allele with more than 30 repeats. Now, the chlid has Down Syndrome, it means a trisomy in chromosome 21, thus one of his parents nondisjunctioned the 21 chromosome during Meiosis. Using PCR we expect to find that the child has the 2 alleles from one parent and 1 allele from the other. If the results say that the mother is the one that failed to segregagte the chromosomes, that is because the child's PCR showed the same exact bands as the mother, plus a third band that coincides with one allele from the father. It would look like this:

3.- A. Loss of function. Such mutations are the ones that causes to lose the normal function of the protein, if TMPRSS2 function is to cleave certain substrate and the mutation took away such ability, then it is a loss of function mutation