Which of the following mechanisms leads to INCREASED transcriptional activity?
A) An sRNA binds to the ribosome binding site.
B) Ribonuclease activity is blocked by sRNA complementary binding to the end of a transcript.
C) The ribosome binding site is made available from sRNA binding to part of it.
D) Recruitment of RNA polymerase is enhanced when sRNA binds to and removes a repressor.
Answer: C
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How does sickle cell disease cause death?
a. The malformed red blood cells cannot transport oxygen. b. The malformed red blood cells can block capillaries. c. The malformed blood cells have a higher affinity for CO2 than for oxygen. d. The mutant hemoglobin polypeptide cannot bind O2 due to a change in three amino acids. e. More cells assume the sickle shape as oxygen concentration in the tissues increases.
Tamryn has a son who has Duchenne muscular dystrophy, which is inherited as an X-linked recessive trait. At a molecular level, the disease is due to lack of the protein dystrophin. Tamryn participates in a study that looks at dystrophin levels in various muscles. The study samples cells from 10 different muscles. The study finds that some cells make dystrophin and some do not. An explanation for this finding is that
A) the mutation is only in some muscle cells. B) Tamryn is making less dystrophin as she gets older. The study should be repeated at different ages. C) the X chromosome that bears the mutation is turned on in some cells but off in others. D) Tamryn does not have a Y chromosome.
Which of the following is not a part of the bark?
a. phloem b. periderm c. cork d. xylem e. resin ducts
Miller and Urey
1.put forth the theory of evolution. 2.created a laboratory simulation of conditions thought to exist on early Earth. 3.discovered they could produce DNA. 4.proved Mendel's work. 5.discovered that they could produce proteins.