7.2 Metabolism

Question 1

Define Metabolism.

Answer 1

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways which manage the material and energy resources of the cell.

Question 2

Define Anabolic and Catabolic pathways.

Answer 2

Anabolic: Pathways that consume energy to build complex molecules from simpler ones (e.g., protein synthesis). Catabolic: Pathways that release energy by breaking down complex molecules (e.g., cellular respiration).

Question 3

Define Exergonic vs. Endergonic reactions.

Answer 3

Exergonic: A spontaneous reaction that releases free energy (−ΔG). Endergonic: A non-spontaneous reaction that absorbs free energy from its surroundings (+ΔG).

Question 4

What is the difference between Hydrolysis and Synthesis?

Answer 4

Hydrolysis: Using water to break a chemical bond (usually catabolic). Synthesis (Dehydration): Removing water to form a chemical bond (usually anabolic).

Question 5

Describe the ATP Cycle.

Answer 5

The continuous process where ATP is broken down into ADP and Inorganic Phosphate (Pi​) to release energy, and then regenerated from ADP and Pi​ using energy from food during cellular respiration.

Question 6

Describe the Graph of an Exergonic reaction.

Answer 6

The energy level of the reactants is higher than the energy level of the products. The curve drops downward, representing a net release of energy (−ΔG).

Question 7

Describe the Graph of an Endergonic reaction.

Answer 7

The energy level of the reactants is lower than the energy level of the products. The curve climbs upward, representing a net gain/storage of energy (+ΔG).

Question 8

Relate the terms: Is an Anabolic reaction typically Exergonic or Endergonic?

Answer 8

Anabolic reactions are Endergonic. They require an input of energy to “build” or synthesize complex molecules from smaller building blocks.

Question 9

Relate the terms: Is a Catabolic reaction typically Exergonic or Endergonic?

Answer 9

Catabolic reactions are Exergonic. They release the energy stored in the chemical bonds of complex molecules as they are broken down.

Question 10

Which part of the ATP Cycle is Catabolic and Exergonic?

Answer 10

The conversion of ATP → ADP + Pi​. This is a hydrolysis reaction that breaks a bond to release energy for cellular work.

Question 11

Which part of the ATP Cycle is Anabolic and Endergonic?

Answer 11

The conversion of ADP + Pi​→ ATP. This is a synthesis reaction that requires an energy input (from cellular respiration) to create a high-energy bond.

Question 12

Provide an example of an Exergonic reaction being linked (coupled) with an Endergonic reaction.

Answer 12

Example: The hydrolysis of ATP (exergonic) is coupled with the building of a protein from amino acids (endergonic). The energy released by ATP is used to drive the protein synthesis.

Question 13

Why must the Exergonic reaction occur “first” or simultaneously in a coupled system?

Answer 13

Because endergonic reactions are non-spontaneous (+ΔG), they physically cannot happen without an external source of energy. The exergonic reaction provides the necessary “push” or free energy required to overcome the energy barrier of the endergonic process.

Question 14

In an exergonic reaction, how does the energy of the products compare to the energy of the reactants?

Answer 14

The products have less energy than the ractants. Since exergonic reactions release energy, the starting materals had more stored energy than the final products.

Question 15

Which process is typically used to break the terminal phosphate bond of ATP to release energy?

Answer 15

hydrolysis

Question 16

The conversion of ADP + Pi into ATP is an example of a(n) ________ reaction. A) exergonic and catabolic B) exergonic and anabolic C) endergonic and catabolic
D) endergonic and anabolic

Answer 16

D) endergonic and anabolic. Building ATP from ADP requires an input of energy, making it both anabolic and endergonic

Question 17

Which of the following is the most accurate relationship between catabolism and anabolism?
A) They are independent processes that do not interact
B) Catabolic reactions provide the energy needed to drive anabolic reactions
C) Both processes are exergonic and release energy into the environment
D) Anabolic reactions provide the energy needed to drive catabolic reactions

Answer 17

B) catabolic reactions provide the energy needed to drive anabolic reactions

Question 18

Do hydrolysis reactions tend to be exergonic or endergonic?

Answer 18

exergonic

Question 19

Do dehydration synthesis reactions tend to be endergonic or exergonic?

Answer 19

endergonic

Question 20

A reaction that releases more energy than it requires is known as

Answer 20

exergonic

Question 21

A reaction that requires more energy than it releases is known as

Answer 21

endergonic

Question 22

Breaking bonds _____ energy while forming bonds _______ energy

Answer 22

requires // releases