In female humans and other mammals, dosage compensation is achieved by the inactivation of one of the two X chromosomes in each cell. Which one of the following does not occur in the X-inactivation mechanism of female mammals?
A. X-inactivation begins with a small region of
the X chromosome that contains a gene for
an X-inactivation specific transcript (Xist).
B. Xist is expressed in low levels except
when an X chromosome is about to be
inactivated.
C. When an X chromosome is about to be
inactivated, Xist RNA transcripts increase
markedly and undergo splicing, but do not
encode a protein.
D. Xist RNA is attracted to and associates
with a protein called the X-chromosome
inactivation center (XIC), which becomes
entirely coated with Xist.
E. Xist RNA recruits factors that promote
DNA methylation, histone modification, and
other changes associated with transcriptional
silencing.
D
You might also like to view...
In fungi, food materials are digested:
a. within food vacuoles b. outside the body c. intracellularly d. by the mitochondria e. by the host organism
When a bacteriophage genome incorporates itself into the chromosome of the host, that phage genome is referred to as a(n) ________
Fill in the blank(s) with correct word
Whether or not an enzyme is active and present within a cell depends on all of the following except
A) if the gene for the enzyme has been turned on and the enzyme made. B) if the enzyme has been activated or inactivated by the addition of a phosphate group. C) whether an inhibitor is bound to the enzyme. D) whether the necessary cofactor is present. E) whether the enzyme catalyzes an endergonic or exergonic reaction.
Which term best describes the relationship between pathogenic bacteria and humans?
A) amensalism B) commensalism C) parasitism D) predation