An enzyme adds a(n) _______ tag to proteins that are recognized by proteasomes for destruction.
ubiquitin
Which of the following does not regulate gene expression after transcription?
Transcription factor binding
Epigenetics may be defined as changes in the expression of a gene or set of genes by _______ and _______.
DNA methylation; chromosomal protein alteration
Regulation of gene expression during the phage lytic cycle does not include
enhancement of the host’s gene transcription.
DNA methylation
involves the modification of the pyrimidine cytosine.
_______ are present in prokaryotes, and bind to and direct the polymerase to specific promoters.
Sigma factors
Which statement about RNA polymerase is true?
Eukaryotes use different RNA polymerases to transcribe rRNA and mRNA.
Gene expression cannot be regulated
during replication.
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.
The amount of HMG CoA reductase would increase.
Operons
consist of a promoter, an operator, and two (or more) structural genes.
A(n) _______ operon is turned off unless needed.
inducible
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 II; the initiation site; TFIID; transcription factors
Prokaryotes and eukaryotes differ in transcription in that
there are three RNA polymerases in eukaryotes.
A retrovirus
encodes a reverse transcriptase.
Which of the following is/are not involved in the process of transcription?
Ribosomes
Bacterial viruses (phages)
require a host cell to replicate.
A(n) _______ operon is turned on unless not needed.
repressible
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.
low; high; lac repressor
_______ genes are expressed at a constant rate most of the time.
Constitutive
x

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