Attenuation of the trp operon fails to occur when
A) a lack of tryptophan causes stalling of ribosomes on the leader sequence of the RNA.
B) an RNA stem-loop forms that allows transcription to continue.
C) an RNA stem-loop that causes transcription to terminate fails to form.
D) the cell has enough tryptophan.
E) the operator is mutated.
D
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What role does clathrin play in receptor-mediated endocytosis?
a. Clathrin is the receptor where the highly specific binding takes place. b. Clathrin initiates the transcription of the receptor proteins that will coat the pit. c. Clathrin attaches to the plasma membrane’s cytoplasmic side, forming the coated pit. d. Clathrin production blocks the formation of the coated pit.
Knoblike sacs where the inner colon lining protrudes through the intestinal wall are called
a. diverticula. b. ulcers. c. haustra d. sphincters. e. appendices.
The blood vessels that supply oxygenated blood to the heart tissue itself are the
A. pulmonary veins. B. coronary arteries. C. coronary sinuses. D. pulmonary trunks. E. venae cavae.
Sister chromatids separate and move toward the poles of the cell during ________ of mitosis
A) telophase B) anaphase C) metaphase D) interphase E) prophase