The addition of a new deoxynucleotide to a growing DNA chain requires more energy than can be obtained by the hydrolysis of ATP to ADP + Pi
What alternative series of reactions is used, and how does this help overcome the energy barrier for DNA synthesis?
The hydrolysis of ATP to ADP is favorable, with a ?G between –11 and –13 kcal/mole. However, this is not sufficient to drive the addition of a nucleotide to the end of a growing DNA strand. Instead, two reactions are used. The first reaction converts ATP to a DNA-linked AMP residue when a phosphodiester bond is formed during DNA synthesis; simultaneously, a pyrophosphate molecule (PPi) is released. In the second reaction, the PPi is hydrolyzed to form two molecules of Pi. This second reaction is also favorable, providing roughly another –13 kcal/mole. Adding up the ?G for the entire process, there will be about –26 kcal/mole to drive the addition of the nucleotide to the growing DNA chain, which is sufficient to drive the reaction strongly in one direction.
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A. their ability to leave their environment relatively unchanged. B. their large body sizes. C. their effect on high amounts of biomass and energy transfer between populations. D. their roles as prey species for predator populations in the community. E. their avoidance of antagonistic interactions.
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Fill in the blank(s) with correct word
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A. 2; 200 B. 4; 100 C. 2; 100 D. 4; 200