Question

The mammalian expression vector shown below contains two genes (Gene 1 and Gene 2) in tandem, separated by an IRES element. These genes are placed downstream of a strong mammalian promoter (CMV). Would both genes be expressed if this vector were transfected into a mammalian cell? Explain with reason/s.

A.

Yes, but first, a long mRNA product containing both Genes 1 and 2 will be made, which would allow for the formation of both translation products

B.

Gene 1 and Gene 2 will be expressed equally. The IRES stimulates the peptidyl transferase

C.

Yes, but Gene 2 will be expressed ten times less than Gene 1. The IRES allows re-entry of the ribosome complex for the translation of Gene 2

D.

No. Eukaryotic genes are not polycistronic

E.

Yes, both Gene 1 and Gene 2 will be expressed equally. The IRES allows re-entry of the ribosome complex for the translation of Gene 2

2.

Human liver expresses apoB-100, but human intestine cells express apoB-48. Do these proteins come from the same gene? State how they are expressed.

A.

Yes; deamination in the intestinal cells converts a C to U in the apoB-100 RNA, which yields an early stop codon

B.

No; they come from two different genes located on different chromosomes

C.

Yes; but cell-type specific recombination yields the apoB-48 gene from the apoB-100 gene

D.

No; they come from two alleles of the same gene, of which one has a C to U mutation

3.

The codons UUA and CUA both produce Leucine and the codons CGA and AGA both produce arginine. How many tRNAs are used for each amino acid in these cases?

A.

Four

B.

One

C.

Two

D.

Three

Answer 1