How do shape changes in RNA polymerase correlate with the stages of transcription?
What will be an ideal response?
Ans: When RNA polymerase binds the promoter to form the closed binary complex, the enzyme is stretched over a length of ~75 base pairs. When promoter recognition is no longer needed and elongation is beginning, the polymerase covers about 50 base pairs. Once the RNA chain reaches a length of 15 to 20 bases, the polymerase contracts further, covering 30 to 40 base pairs.
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A cytologist is examining a tissue under an electron microscope. He notices that the endoplasmic reticulum of each cell is extremely rough in appearance and he knows that the rough appearance is because of the ribosomes embedded there. He asks why there are so many ribosomes. You respond,
A. "This tissue exports lipids and is very involved with mRNA production." B. "This tissue exports proteins to other areas of the body." C. "This tissue exports various nucleic acids, hence the large number of ribosomes present on the endoplasmic reticulum in each of those cells."
In a neuron at rest, the membrane is most permeable to
A. potassium. B. sodium. C. chloride. D. calcium. E. magnesium.
What happens when rocks are newly exposed (or created) in an area?
a. k-selection b. r-selection c. primary succession d. secondary succession
Which of the following statements about Neisseria meningitis is FALSE?
A) A healthy carrier state can exist. B) It is encapsulated. C) It is typically transmitted by droplet aerosols or direct contact with secretions. D) Its most distinguishing feature is a unique rash. E) It is a gram-positive anaerobe.