Biol. 10504 Exam #2 Fall, 2009 70 questions
1. A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in
which the transgene has integrated into the yeast genome. In four of the lines, the transgene is
expressed strongly, but in the fifth there is no expression at all. Which is a likely explanation
for the lack of transgene expression in the fifth cell line?
(A) A transgene integrated into a heterochromatic region of the genome
(B) A transgene integrated into a euchromatic region of the genome
(C) The transgene was mutated during the process of integration into the host cell
genome
(D) The host cell lacks the enzymes necessary to express the transgene
(E) A transgene integrated into a region of the genome characterized by high histone
acetylation
2. The fact that RNA can have catalytic activity is important in thinking about prebiotic
evolution because it shows:
(A) how chickens came from eggs;
(B) that a molecule could have simultaneously evolved both informational and catalytic
functions;
(C) how proteins are synthesized;
(D) more than one of the above are correct;
(E) all of the above (a-c) are correct.
3. Up to 60% of all medicines used today exert their effects by influencing what structures in
the cell membrane?
(A) tyrosine-kinases receptors
(B) ligand-gated ion channel receptors
(C) growth factors
(D) G proteins
(E) cholesterol
4. Transcription of the structural genes in an inducible operon:
(A) occurs continuously in the cell
(B) starts when the pathway’s substrate is present
(C) starts when the pathway’s product is present
(D) stops when the pathway’s product is present
(E) does not result in the production of enzymes
5. Complementary bases in the DNA double helix are connected by _____ bonding:
(A) covalent,
(B) ionic,
(C) hydrogen,
(D) van der Waals.
(E) James
