mol bio final exam practice questions

Transport of the protein out of the cell

Which of the following is NOT generally a way to control the activity of a positive regulatory transcription factor?
a. Binding of an inhibitor that affects its ability to bind to DNA
b. Synthesis of protein in a specific tissue type
c. Covalent modification of a protein
d. Transport of the protein out of the cell
e. Binding of a ligands

may require a coactivator with an active domain

An activator that does NOT have an activating domain:
a. must directly interact with RNA polymerase.
b. must also not have a DNA-binding domain.
c. may require a coactivator with an active domain.
d. is mutant and cannot activate a gene.
e. is called a repressor.

ATPase

All chromatin remodeling complexes have a subunit for __________ that is encoded by one member of a gene superfamily.
a. histone-binding
b. ATPase
c. repressor-binding
d. DNA-binding
e. transcription factor-binding

displacing nucleosomes from a promoter

Transcription activation via a remodeling complex often involves:
a. histone deacetylation.
b. recruiting an activator to a promoter.
c. DNA methylation.
d. displacing nucleosomes from a promoter.
e. breaking apart nucleosomes

DNA methylation is generally associated with transcriptional inactivity

Which statement best describes the relationship between methylation and gene activity?
a. DNA methylation is generally associated with transcriptional inactivity.
b. DNA methylation is generally associated with translational inactivity.
c. DNA methylation is generally associated with transcriptional activity.
d. Histone methylation is generally associated with transcriptional inactivity.
e. Histone methylation is generally associated with transcriptional activity.

occurs in a series of transesterifications that require no hydrolysis for energy

The self-splicing of Group I introns:
a. requires energy from the hydrolysis of ATP.
b. gains energy from exergonic reactions involving inorganic compounds.
c. occurs in a series of transesterifications that require no hydrolysis for energy.
d. requires energy from the hydrolysis of GTP.
e. gains energy directly from an electron transport chain.

viroids

“Hammerheads” are self-cleaving structures found in:
a. mitochondria.
b. viroids.
c. retroviruses.
d. eubacteria.
e. archaea.

transiently binds deacylated tRNA

The ribosomal E site:
a. binds aminoacyl-tRNA.
b. binds the peptidyl-tRNA.
c. binds the Shine-Dalgarno sequence.
d. transiently binds deacylated tRNA.
e. binds the mRNA start codon.

assist the entry of the inhibitor tRNA into the ribosome

In bacteria, the function of IF-2 is to:
a. prevent premature binding of the 50S ribosomal subunit.
b. assist the entry of the initiator tRNA into the ribosome.
c. facilitate the binding of the 30S ribosomal subunit to mRNA.
d. prevent entry of aminoacyl-tRNA into the A site.
e. stabilize the 30S ribosomal subunit.

EF-Tu

In bacteria, which protein complexes with aminoacyl-tRNAs and GTP to bind to the ribosomal A site?
a. EF-Tu
b. eIF2
c. IF-2
d. EF-Ts
e. EF-G

23S rRNA

What part of the bacterial ribosome has peptidyl transferase activity?
a. A protein in the 30S ribosomal subunit
b. 23S rRNA
c. A protein in the 50S ribosomal subunit
d. 16S rRNA
e. 5S rRNA

ATPase

Which of the following is NOT usually an independent domain of an activator transcription factor?
a. ATPase
b. Dimerization
c. DNA-binding
d. Transcription activation
e. All of these are potential independent domains of an activator

most active promoters are free of nucleosomes

Which of the following is true about chromatin organization at active promoters?
a. It contains a high density of nucleosomes.
b. It is always free of nucleosomes.
c. Most active promoters are free of nucleosomes.
d. DNA of promoters is heavily methylated.
e. Histone H3 is methylated at the K9 position

Cytosine deamination

Which of the following types of DNA damage directly results in a mismatched base-pair?
a. Cytosine deamination
b. Ultraviolet irradiation
c. Double-strand breaks
d. Base methylation
e. Depurination

base excision repair

Glycosylases and lyases are directly involved in:
a. recombination repair.
b. photoreactivation.
c. base excision repair.
d. mismatch repair.
e. nucleotide excision repair.

base pairing between spacer/PAM RNAs and phage DNA protospacer sequences, preventing expression of phage genes

Which of the following is crucial for CRISPR-Cas9 mediated phage immunity?
a. Inhibition of translation of phage mRNAs by base pairing between spacer/PAM RNA and viral mRNAs
b. Base pairing between spacer/PAM RNAs and phage DNA protospacer sequences, preventing expression of phage genes
c. Prevention of phage DNA replication by inhibition of initiation
d. Ribozyme activity of the spacer/PAM RNA
e. Some combination of all of these mechanisms

siRNA-encoding genes that produce a transcript that folds to become double-stranded

Eukaryotic siRNAs originate from:
a. viral infection.
b. siRNA-encoding genes that produce a transcript that is processed into many small RNAs.
c. degraded messenger RNAs.
d. siRNA-encoding genes that produce a transcript that folds to become double-stranded.
e. introns removed during mRNA processing.

Drosha

Which of the following proteins is responsible for the first step in processing pre-miRNA?
a. Dicer
b. Argonaute
c. Drosha
d. Exportin-5
e. MCPP1

piRNAs

Which of the following is a special class of eukaryotic miRNAs that are active in germ cells?
a. CRISPRs
b. CUTs
c. piRNAs
d. siRNAs
e. sRNAs