Chapter 8- An Introduction to Metabolism

Question 1

Metabolism

Answer 1

The totality of an organism’s chemical reactions

Question 2

Metabolic pathway

Answer 2

A sequence of chemical reactions that transforms a starting molecule into a final product.

Question 3

Enzymes

Answer 3

Proteins that accelerate (catalyze) spontaneous chemical reactions.

Question 4

Catabolic pathways

Answer 4

BREAKS DOWN molecules
Releases energy (ex: ATP)

Question 5

Anabolic pathways

Answer 5

Builds molecules
CONSUMES energy

Question 6

1st law of thermodynamics

Answer 6

The energy of the universe is constant. No energy can be created or deleted.

Question 7

2nd law of thermodynamics

Answer 7

Every energy transfer increases the entropy of the universe

Question 8

Entropy

Answer 8

“Disorder”
The more random assortment of molecules

Question 9

Spontaneous process

Answer 9

Occurs without an energy input
Energetically favorable
Increase in entropy

Question 10

Nonspontaneous process

Answer 10

Requires an energy input
Decreases entropy

Question 11

Gibbs free energy
(Include formula)

Answer 11

Defines the amount of FREE ENERGY in a system
ΔG= G (final state) - G (initial state)

Question 12

In the Gibbs free energy, if G is negative, the reaction is ___________ and therefore __________.
If G is positive, the reaction is __________ and therefore _________.

Answer 12

Spontaneous, exergonic
Nonspontaneous, endergonic

Question 13

Exergonic reaction

Answer 13

Releases free energy, SPONTANEOUS
*Downhill

Question 14

Endergonic reaction

Answer 14

Absorbs free energy
Nonspontaneous
*Uphill

Question 15

Which is more energetically favorable? Exergonic or endergonic?

Answer 15

Exergonic

Question 16

Activation

Answer 16

The initial amount of energy needed to “activate” an exergonic reaction.

Question 17

Equilibrium

Answer 17

The state of maximum stability (G=0)

Question 18

ATP
1: structure
2: how it transfers energy

Answer 18

1: Ribose+adenine+3 phosphate groups
2: Hydrolysis breaks phosphate bonds, releases energy. Energy is transferred via phosphorylation.

Question 19

Phosphorylation
(also include the enzyme that catalyzes it)

Answer 19

The way ATP drives endergonic reactions
Transfers a phosphate group to a reactant, putting it in a less stable (more energetic) state.
Catalyzed by the enzyme kinase.

Question 20

Enzyme

Answer 20

A catalyst that helps speed up exergonic reactions.
Lower the activation energy requiered.
Operate under optimal temperature and pH

Question 21

Enzyme substrate complex

Answer 21

Formed by the substrate binding to the enzyme’s active site.
Enzyme slightly changes shape to fit the substrate “snug and tight”

Question 22

What are 4 ways an enzyme can lower the activation barrier?

Answer 22

1: Orient the substrates in the correct position
2: Provide a suitable environment (pH, temp, etc)
3: Covalently bond to the substrate
4: Strain substrate bonds

Question 23

What are the functions of Cofactors/Coenzymes?

Answer 23

Both help an enzyme.
Cofactors: Inorganic compounds that assist the enzyme by helping provide a more suitable shape to fit the substrate
Coenzyme: Same as cofactors, except organic

Question 24

Explain the details of the Michaelis-Menten Enzyme Kinetics
V(max) and K(m)

Answer 24

V(max)- the maximum velocity that an enzyme can operate at
K(m)- the number of substrates available in order for an enzyme to operate at 50% of its maximum speed.

Question 25

What is allosteric regulation?

Answer 25

The binding of a molecule to a non-active site, affecting the active site. In other words, a type of regulation that affects the rate at which an enzyme operates.

Question 26

What is competitive inhibition? What happens to the V(max) and K(m)?

Answer 26

It is when the inhibitor (small molecule) binds to the enzyme's active site and competes with the substrate. V(max) stays the same K(m) increases

Question 27

What is an uncompetitive inhibitor? How does it affect the V(max) and K(m)?

Answer 27

Bind only to the SIDE of an enzyme ONLY when it ALREADY has a substrate in it. Prevents it from completing its reaction. V(max) decreases, K(m) decreases

Question 28

What are noncompetitive inhibitors? How does it affect the V(max) and K(m)?

Answer 28

A type of mixed inhibitor. Bind to the empty enzyme AND the free enzyme with equal chance. Different from noncompetitive inhibitors- binds to EMPTY enzymes AS WELL. V(max) decreases, K(m) stays the same

Question 29

What are mixed inhibitors? How do they affect the V(max) and K(m)?

Answer 29

Bind to an empty enzyme and an enzyme-substrate complex (occupied enzyme) with different affinities. V(max) decreases. K(m) can increase OR decrease, depending on the type of mixed inhibition.

Question 30

Cooperativity

Answer 30

When binding of a substrate to one active site of an enzyme activates/deactivates ALL the enzyme's active sites

Question 31

How does positive cooperativity affect the Michaelis-Menten curve?

Answer 31

The curve becomes sigmoidal. (there is a sudden steep "boost" in the middle of the curve)

Question 32

What measures the extent to which enzyme cooperativity occurs? What do each of the values signify?

Answer 32

The Hill coefficient (n) measures the extent to which cooperativity occurs. 1: n>1: Positive cooperativity. (sigmoidal curve) 2: n=1: No cooperativity (hyperbolic shape) 3: n<1: Negative cooperativity (logarithmic shape)

Question 33

What is a type of molecule that exhibits cooperativity?

Answer 33

Hemoglobin

Question 34

What is feedback inhibition? Why is it good for a cell?

Answer 34

Feedback inhibition is when the end product of a metabolic pathway shuts down the pathway. This is good, because it regulates the amount of a process that can occur.