ATP1

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Ch. 6 Contents

General
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------------------Online--------------------------------wilcox@sunline.net Ch. 6 Metabolism of carbohydrates, fats, proteins, nucleic acids

5. ATP Coupling

"ATP powers cellular work by coupling exergonic to endergonic reactions," i.e. cells do their work by breaking down molecules (exergonic), releasing the chemical energy and then using this energy to build, maintain and grow (endergonic). The close relationship between the exergonic and endergonic processes, providing for an energy transfer, is described as a coupling.

Consult your text and list the three kinds of work a cell does:
______________________
______________________
______________________

5.1	The structure of ATP.
5.2	Hydrolysis of ATP to ADP
5.3	Phosphorylation of ADP to ATP
5.4	Coupling exergonic to endergonic reactions.

5.1 The structure of ATP.

Compare the structure of the ATP molecule (Fig. 6.8 of text) with the monomers studied in Chapter 5. ATP most closely resembles: _____

a) a monosaccharide
b) a fatty acid
c) an amino acid
d) a nucleotide

ATP acts much like a rechargeable battery. Fully charged it is ATP (adenosine triphosphate). When it has transferred its energy to another molecule, by transferring a phosphate functional group, ATP become ADP (adenosine diphosphate). ATP most closely resembles d) a nucleotide.

Figure 6.10

For instance: the first step in breaking glucose down into carbon dioxide and water, is to phosphorylate it. Consult Figure 9.9 Glycolysis in text. Can you draw a picture of the enzyme hexokinase catalyzing the production of glucose 6-phosphate, in the space below?

check your answer Likewise, the first step in an anabolic reaction, say building a disaccharide out of two monosaccharides, is to phosphorylate one or both of the molecules involved.

5.2 Hydrolysis of ATP to ADP
What happens to break the bonds of the phosphate of ATP releasing it for transfer to glucose?

condensation synthesis/dehydration synthesis
hydrolysis

Answer: see Figure 6.8 b in your text.

Consult Figure 5.2 of your text and write the definition of "hydrolysis" below: ________________________________________________.

**5. ATP Coupling**
5.1	The structure of ATP
5.2	Hydrolysis of ATP to ADP
5.3	Phosphorylation of ADP to ATP
5.4	Coupling exergonic to endergonic reactions