Chapter 8

Question 1

DeltaG and the reaction rate are…?

Answer 1

independent.

Question 2

What is the reaction rate?

Answer 2

How quickly a reaction happens.

Question 3

What does DeltaG tell us?

Answer 3

If the reaction will occur without a net input of energy.

Question 4

How does temperature influence reaction rate?

Answer 4

As temp increases so does reaction rate.

Question 5

How can cells increase or decrease the reaction rate?

Answer 5

By manipulating the activation energy.

Question 6

What is activation energy?

Answer 6

The energy you have to invest to get the reactants to the transition state.

Question 7

What is the transition state?

Answer 7

The intermediate state where all the components are separated and ready to collide to form a reaction producing the products.

Question 8

on the graph displaying a chemical reaction what does it mean if the products are lower than the reactants?
Or if the reactants are lower than the products?

Answer 8

1. ) if the products are the lowest point on the chemical reaction graph the reaction is exergonic or spontaneous.
2. ) if the products are the higher than the point of the reactants on the chemical reaction graph, the reaction is endergonic or non-spontaneous.

Question 9

What does lowering the activation energy do?

Answer 9

It creates a faster rate of reaction.

Question 10

How do cells lower activation energy?

Answer 10

Via catalyst.

Question 11

What are enzymes?

Answer 11

A class of proteins that serve as a biological catalyst used to lower the activation energy of a reaction, thus increasing the rate of the reaction.

Question 12

T/f Each is enzyme is the same shape?

Answer 12

false, each enzyme has to be shaped perfectly so that it fits each with the reactants or substrates. in order for them to be brought to their transition states.

Question 13

The correct shaped enzyme paired with correct substrate/reactant = ?

Answer 13

the reactants reaching their transition state

Question 14

What is the portion of the enzyme where the substrates nestle?

Answer 14

The active site.

Question 15

Describe how you can tell the difference between an uncatalyzed and catalyzed reaction?

Answer 15

You can give each an increase in substrate concentration.

• Catalyzed reaction: they initial take up producing massive amounts of products but then slowly tappers off.
• Uncatalyzed reaction: there is a slow and linear increase in the rate of product formation.

Question 16

T/F: the same enzyme in two different organism’s will not be exactly the same? Why?

Answer 16

• Those two organisms don’t live in the exact same environments. Proteins fold differently based on environment, therefor the “same” enzymes will have differing structures.

Question 17

Describe the steps of the model of enzyme action?

Answer 17

1. ) Initiation: substrates bind to the active site in a specific orientation, forming an an enzyme-substrate complex
2. Transition state facilitation: interactions between enzyme and substrate lower the activation energy.
3. Termination: products have lower affinity for active site and are released. Enzyme is uncharged after the reaction.

Question 18

What is competitive inhibition?

Answer 18

cell produces some molecule that is similar enough in shape as the substrate to fit into the active site,
- but it is also different enough in shape that it doesn’t get modified by the active site.
EFFECTIVLY BLOCKING FURTHER SUBSTRATES FROM ENTERING THE ENZYME.

Question 19

Allosteric regulation (inhibition) ?

Answer 19

A molecule binds to some other site ( not the active site) and causes the active site to change in shape.
- This in turn allows for the active site to no longer interact with the substrate.

Question 20

Allosteric regulation (activation) ?

Answer 20

A molecule binds to some other site ( not the active site) and causes the active site to change in shape.
- This in turn allows for the active site to better intake of the substrates.

Question 21

what are the ways in which an enzyme can be activity regulated?

Answer 21

1. What is competitive inhibition
2. Allosteric regulation (inhibition)
3. Allosteric regulation (activation)

Question 22

What is the difference in Allosteric vs Competitive regulation?

Answer 22

Allosteric regulation: the molecules that regulates the activity of the enzyme binds to the some other site on the enzyme, rather than the active site like it does in competitive regulation.

Question 23

T/F, an enzyme can simultaneously catalyze an exergonic and endergonic reaction?
Why or why not?

Answer 23

True, because: The energy released form the exergonic reaction can be used to drive the endergonic reaction.

Question 24

What is the idea of an enzyme catalyzing an exergonic and endergonic reaction at the same time known as?

Answer 24

Energetic coupling

Question 25

What are the two forms of energetic coupling?

Answer 25

1. ) the exergonic reaction is ATP hydrolysis.

2. ) there exergonic reaction is a redox reaction

Question 26

What is a Metabolic Pathway?

Answer 26

Is a set of sequential enzyme-catalyzed reactions that culminate the formation of some important biochemical product.

Question 27

What is feedback inhibition?

Answer 27

the product of one step in the pathway acts as an allosteric inhibitor of an earlier step

Question 28

What is the retro-evolutionary hypothesis?

Answer 28

• Some key molecule, nucleotide, and some readily available substrate was available in the environment and an enzyme evolved that could take that substrate and turn it into the nucleotide.
• Now once this has happened for a while selective pressure occurs to make more substrates so the first enzyme can make more of the enzyme 2.
• this happens repeatedly.