The expression of the lac structural genes is _______ when lactose is absent from the culture medium and is _______ when lactose is added, because lactose binds to the _______ and inactivates it.ow;
high; lac promoter
high; low; lac operator
low; high; lac repressor
low; high; lac operator
high; low; lac inducer
low; high; lac repressor
A(n) _______ operon is turned off unless needed.

constitutive
clustered
repressible
inducible
non-inducible

inducible
Predict what would happen to the synthesis of the enzyme HMG CoA reductase (an enzyme that catalyzes an initial step in the synthesis of cholesterol) if trichostatin A, a histone deacetylase inhibitor, is added to liver cells.

HMG CoA reductase would undergo a conformational change and lose function.
The amount of HMG CoA reductase would increase.
HMG CoA reductase would not be synthesized.
The amount of HMG CoA reductase would decrease.
HMG CoA reductase levels would not change.

The amount of HMG CoA reductase would increase.
4. A(n) _______ operon is turned on unless not needed.

repressible
active
constitutive
inducible
clustered

repressible
An enzyme adds a(n) _______ tag to proteins that are recognized by proteasomes for destruction.

methyl
lactate
methionine
phosphate
ubiquitin

ubiquitin
_______ are present in prokaryotes, and bind to and direct the polymerase to specific promoters.

Ribosomes
Proteases
Sporulation proteins
Reverse transcriptatses
Sigma factors

Sigma factors
Operons

consist of a promoter, an operator, structural genes, and a repressor gene.
include inducer genes.
are common in eukaryotes.
consist of structural genes only.
consist of a promoter, an operator, and two (or more) structural genes.

consist of a promoter, an operator, and two (or more) structural genes.
Epigenetics may be defined as changes in the expression of a gene or set of genes by _______ and _______.

transcription factors; DNA methylation
promoters; DNA methylation
DNA methylation; chromosomal protein alteration
promoters; chromosomal protein alteration
chromosomal protein alteration; transcription factors

DNA methylation; chromosomal protein alteration
Bacterial viruses (phages)

have a cell membrane.
can reproduce on their own.
are alive.
require a host cell to replicate.
carry out metabolism.

require a host cell to replicate.
Which of the following does not regulate gene expression after transcription?

Alternative splicing
Transcription factor binding
Translational repressor proteins
Modifications to the 5? cap
MicroRNA

Transcription factor binding
Regulation of gene expression during the phage lytic cycle does not include

stimulation of viral late gene transcription.
downregulation of the host’s gene transcription.
enhancement of the host’s gene transcription.
enhancement of viral early gene transcription.
binding of a host RNA polymerase to a viral promoter.

enhancement of the host’s gene transcription.
Which statement about RNA polymerase is true?

Bacteria contain more regulatory sequences than eukaryotes do.
In eukaryotes, RNA polymerase II binds directly to the DNA promoter and initiates transcription.
Eukaryotes use RNA polymerase III to transcribe ribosomal RNA.
Eukaryotes use different RNA polymerases to transcribe rRNA and mRNA.
Bacteria use RNA polymerase III to transcribe tRNA and mRNA.

Eukaryotes use different RNA polymerases to transcribe rRNA and mRNA.
Prokaryotes and eukaryotes differ in transcription in that

initiation of transcription is more complex in prokaryotes.
eukaryotic promoters contain operons.
there are three RNA polymerases in eukaryotes.
prokaryotic promoters have a TATA box.
structural genes for a pathway are less likely to be clustered in prokaryotes.

there are three RNA polymerases in eukaryotes
DNA methylation

involves the modification of the pyrimidine cytosine.
is not important in the development of mammalian embryos.
is not abundant in promoters.
requires a histone methylase.
does not repress the transcription of genes.

involves the modification of the pyrimidine cytosine.
Gene expression cannot be regulated

after transcription but before translation.
during transcription.
at or after translation.
before transcription.
during replication.

during replication.
_______ genes are expressed at a constant rate most of the time.

Inducible
Clustered
Constitutive
Repressed
Activator

Constitutive
Which of the following is/are not involved in the process of transcription?

TATA box
RNA polymerase
Ribosomes
Promoters
Transcription factors

Ribosomes
A retrovirus

has a single-stranded DNA genome.
has a double-stranded RNA genome.
integrates its genome directly into the host’s genome.
encodes a reverse transcriptase.
has a double-stranded DNA genome.

encodes a reverse transcriptase.
In the initiation of the transcription of protein-coding genes in eukaryotes, _______ cannot bind directly to _______. Initiation requires _______ and other regulatory proteins called _______.

RNA polymerase III; the initiation site; TFIID; initiation factors
RNA polymerase I; the TATA box; TFIID; transcription factors
RNA polymerase II; the initiation site; TFIID; transcription factors
RNA polymerase I; the TATA box; initiation factors; TFIID
TFIID; RNA polymerase I; an initiation site; transcription factors

RNA polymerase II; the initiation site; TFIID; transcription factors
structural genes

code for structural proteins.
encode proteins not involved in gene regulation.
are absent in eukaryotes.
are regulatory regions of DNA.
are always constitutively expressed.

encode proteins not involved in gene regulation.
x

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