Chapter 8 an Introduction to Metabolism

Question 1

what is a catabolic pathway?

Answer 1

A metabolic pathway which releases energy by breaking down complex molecules to simpler compounds.
ex. cellular respiration

Question 2

What are anabolic pathways?

Answer 2

pathways that consume energy to build polymers from monomers
ex. synthesis of amino acids

Question 3

What is kinetic energy?

Answer 3

energy associated with the relative motion of objects

Question 4

What is thermal energy?

Answer 4

a type of kinetic energy associated with the random movement of atoms or molecules

Question 5

What is potential energy?

Answer 5

energy matter posseses because of its location or structure.

Question 6

What is chemical energy?

Answer 6

term used by biologists to refer to potential energy available for release in a chemical reaction

Question 7

Complex molecules are high in ___ energy

Answer 7

chemical/potential

Question 8

A glucose molecule tends to be ___ unstable than the smaller molecules it can become, meaning it has a ___ delta G

Answer 8

more
higher

Question 9

When is metabolism at equilibrum?

Answer 9

When the cell is dead. If it were at equilibrium it would not be able to do work.

Question 10

Describe the process by which the phosphate bonds in ATP can be broken. What type of reaction is this?

Answer 10

hydrolytic, exergonic rxn
terminal phosphate is broken by H2O
inorganic phosphate leaves the ATP and it becomes ADP

Question 11

Why is the delta G in ATP hydrolysis greater than the delta G of ATP hydrolysis in standard conditions

Answer 11

the conditions in the cell are different, reactant and pdt concentrations differ from 1M

Question 12

Why is the description of ATP phosphate bonds as “high-energy” misleading?

Answer 12

the reactants (ATP and water) have high energy relative to the energy of the products (ADP and phosphate)

the release of energy during ATP hydrolysis comes from the change of the system rather than the phosphate bonds themselves

Question 13

Why does ATP hydrolysis release so much energy?

Answer 13

the three phosphate groups in ATP are negatively charged and repulse each other. Think of them as a compressed sprign

Question 14

What is phosphorylation? When is it performed by the cell?

Answer 14

transfer of a phosphate group from ATP to some other molecule called a phosphorylated intermediate
couples exergonic and endergonic reactions

Question 15

As temperature increases, enzymatic reactions ___ to a certain point

Answer 15

increase

Question 16

What is feedback inhibition?

Answer 16

a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway

Question 17

How do an activator and an inhibitor have different effects
on an allosterically regulated enzyme?

Answer 17

The activator binds in such a way that it stabilizes the active form of an
enzyme, whereas the inhibitor stabilizes the inactive form.

Question 18

Choose the pair of terms that correctly completes this sentence:
Catabolism is to anabolism as ____________ is to ____________.
(A) exergonic; spontaneous
(B) exergonic; endergonic
(C) free energy; entropy
(D) work; energy

Answer 18

Q1. B

Question 19

Most cells cannot harness heat to perform work because
(A) heat does not involve a transfer of energy.
(B) cells do not have much thermal energy; they are
relatively cool.
(C) temperature is usually uniform throughout a cell.
(D) heat can never be used to do work.

Answer 19

Q2 C

Question 20

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
(A) add more of the enzyme.
(B) heat the solution to 90°C.
(C) add more substrate.
(D) add a noncompetitive inhibitor

Answer 20

Q4, A