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Lecture 26

BIOL 112 Lecture Notes - Lecture 26: Coupling Reaction, Exergonic Reaction, Endergonic ReactionPremium


Department
Biology
Course Code
BIOL 112
Professor
Megan Barker
Lecture
26

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Nov. 14th, 2014
BIOL 112 - Biology of the Cell - Chapter 3 (Lecture 26):
Introduction to Metabolism
ATP
Coupled Reactions
Recapitulation of the Last Lecture
Metabolism consists of anabolic and catabolic reactions
Anabolic process breaks down ATP and synthesizes macromolecules
Needs energy, endergonic (positive G)
Catabolic process breaks down macromolecules to generate ATP
Releases energy, exergonic (negative G)
ATP
The more metabolically active the cell, the more ATP that will be generated and used
It has high potential energy, why?
ATP works by phosphorylation (transferring a phosphate group is a highly exergonic
reaction and releases and lot of energy)
Four negative charges in the three phosphate groups repel each other (thus high
potential energy)
Adding the water molecule to ATP
Separate ATP into ADP and phosphate group
ADP + phosphate is more stable and strongly bonded than ATP (becasue of less
repulsion)
Adenosine: ribose + adenine
Adenosine 5’-monophosphate: adenosine and one phosphate group
Adenosine 5’-diphosphate: adenosine and two phosphate groups
Adenosine 5’-triphosphate: adenosine and three phosphate groups
Questions
Which of the changes in this chemical system listed below contribute to the availability of
free energy to do work?
Change from weakly bonded to strongly bonded
A change from motion restricted to less restricted motional state
What happens when ATP breaks down into ADP and pi?
delta G- negative (releases energy)
delta H - negative
delta T - positive (more motional freedom)
Coupled Reaction
Biosynthetic reaction (synthesis of molecules) have a positive G, which is not
spontaneous
Coupled reactions help biosynthetic reactions happen
Endergonic reactions are coupled with exergonic reactions
● Example
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