Exam 3 review
The critical step in the regulation of most bacterial genes occurs _____________.
A. during transcription.
B. at release of mRNA.
C. during ranslation.
What would be the phenotype of a nonsense mutation in the lac repressor function?
A. constitutive expression of the Lac operon.
B. inducible expression of the Lac operon.
C. permanently repressed expression of the Lac operon.
D. cannot predict what would happen to expression of the Pac operon
Transcription and translation can be coupled in bacteria but not eukaryotes since
A. there is no nuclear membrane in prokaryotes.
B. there is no nuclear membrane in eukaryotes.
C. the bacterial DNA is in the nucleoid
D. eukaryotic chromosomes are found in nucleoids.
Proteins that have their activity regulated by binding of another molecule at a site other than the active site are termed
B. allosteric proteins.
C. regulatory proteins.
D. activator proteins.
E. inhibitory proteins.
Catabolic pathways that break down complex substances into more usable units are usually regulated by the
A. end products of the pathway.
B. the levels of the molecule that is to be broken down.
C. other metabolites that are limiting.
D. other enzyme binding..
How is glucose involved in the catabolite repression of the lactose operon?
A. It has nothing to do with regulation of the lactose operon.
B. It results in decreased cAMP levels, which in turn leads to decreased CRP binding; thus the lac operon is repressed even if lactose is present along with the glucose.
C. It is also a substrate for β-galactosidase and thus competes with lactose for this enzyme.
D. Its presence in the cell increases the amount of lac repressor in the cell.
A common amino acid motif found in many of the polypeptides that function as repressors is
A. Leucine zipper motif.
B. Zinc finger motif.
C. Helix-turn-helix motif.
D. Helix-loop-helix motif.
- As a general principle of gene regulation through operons, regulatory genes encode
A. trans-acting proteins that interact with cis-acting DNA elements.
B. cis-acting proteins that interact with cis-acting DNA elements.
C. cis-acting proteins that interact with trans-acting DNA elements.
D. trans-acting proteins that interact with trans-acting DNA elements.
Transcription in prokaryotes and eukaryotes is similar in that
A. transcriptional machinery controls compaction and decompaction of chromatin.
B. the mRNA produced can undergo alternative splicing.
C. both prokaryotic and eukaryotic proteins have identical affinities for DNA.
D. both are contained within the cell nucleus.
E. both are regulated by attachment of proteins to DNA adjacent to the gene being transcribed.
The primary point of control for most genes for the amount of gene product synthesized is
A. termination of replication.
B. transport of mRNA to the cytoplasm.
C. initiation of transcription.
D. alternative splicing.
E. regulation of translation.
Zinc-finger peptide motifs are responsible for what aspect of protein function?
A. Kinase activity
B. DNA binding
C. mRNA splicing
D. DNA replication
DNA sequences that serve as binding sites for proteins regulating transcription and are often found adjacent to a gene are said to be
D. origins of transcription.
E. transcription factors.
What is the name of the cis-acting DNA sequence that serves as the binding site for the transcriptional initiation complex?
What is the term for the cis-acting DNA sequences that often function at a distance from the gene they are regulating?
A. Promoter elements
B. Terminator elements
C. Enhancer elements
D. Regulator elements
E. Initiator elements
In generating a reporter construct to study gene regulation, the reporter gene introduced replaces
B. a random region of DNA.
C. the cis-acting regulatory DNA sequence.
E. the coding region of the gene being studied.
The gene products encoded by trans-acting elements perform their function by
A. associating with regulatory sequences distant from the gene from which they were transcribed.
B. regulating the expression of the gene from which they were transcribed.
C. the association of nucleotides with the elongating RNA transcript.
D. physically associating with DNA polymerase.
E. regulating the activity of telomerase.
What is the term for the repeating structural unit of chromatin, consisting of approximately 200 base pairs of DNA and associated histone proteins?