Understand structure and importance of ATP

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AP Biology › Understand structure and importance of ATP

Questions 1 - 6
1

Which is not part of an ATP molecule?

alpha phosphate, beta phosphate, and gamma phosphate groups

ribose sugar

adenine

threonine

Explanation

ATP consists of 3 phosphate groups, a ribose sugar, and adenine.

2

Which is NOT a reason that the phosphoanhydride bonds of ATP are high energy?

Repulsion of positively charged phosphate and negatively charged oxygen

Resonance stabilization of products of ATP hydrolysis

Entropy is increased when bonds are broken

Large mass of phosphate provides significant energy when combusted

Explanation

The phosphoanhydride bonds of ATP, or the bonds between phosphate molecules, are high energy. This is due to the close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. Also, there is resonance stabilization of the products of ATP hydrolysis (ADP and Pi); thus ADP is more stable than ATP. Additionally, entropy is increased when ATP is hydrolyzed; the second law of thermodynamics states that the entropy of a system always increases.

3

What is the primary energy currency for cells?

oxygen

GTP

ATP

carbohydrate

Explanation

ATP is the primary energy currency for cells. The phosphoanhydride bonds of ATP, or the bonds between phosphate molecules, are high energy. This is due to the close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. Also, there is resonance stabilization of the products of ATP hydrolysis (ADP and Pi); thus ADP is more stable than ATP. Carbohydrates are broken down during glycolysis to produce ATP.

4

Which is true of an ATP molecule?

When hydrolyzed, delta G> 0

It is unstable

It is used for long-term energy storage

When hydrolyzed, a phosphoanhydride bond is formed

Explanation

ATP is unstable; there is close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. When hydrolyzed, delta G is <0 (exergonic). ATP is not used for long term-energy storage, as it is unstable. When hydrolyzed, a phosphoanhydride bond is broken.

5

Which is true of ADP

It contains 2 phosphate groups

ATP is produced when ADP is broken down

It contains more energy than ATP

It contains 3 phosphate groups

Explanation

When ATP is hydrolyzed and a phosphoanhydride bond is broken, ADP and a phosphate are the products. ADP then has 2 phosphate groups.

6

Which cellular process produces ATP?

DNA synthesis

Cellular respiration

Na+/K+ pump

mitosis

Explanation

Cellular respiration is the process through which ATP is produced through the oxidation of glucose.

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