To attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid
, but it is not able to attach the tRNA. What must occur for the final attachment to occur?
A) The ATP must first have to attach to the tRNA.
B) The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme.
C) The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase.
D) The tRNA molecule must alter its shape to be able to fit into the active site with the other two molecules.
E) The end of the tRNA must be cleaved before it can have an attached amino acid.
Answer: B
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A. A biological catalyst. B. Energy from ADP. C. A pump, to drive a concentration gradient. D. A mechanism to control self-replication. E. Both a mechanism to control self-replication and energy from ADP.
If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring
will be produced? a. all intermediate forms b. all tall
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In 1859, naturalist ________ suggested an explanation for why evolution occurs.
A. Thomas Malthus B. Peter Grant C. Charles Darwin D. Charles Lyell E. Robert McKormick