Intermediary Metabolism 1

Question 1

Stability, balance, or equilibrium within a cell or body.

Answer 1

Homeostasis

Question 2

The level or point at which a variable physiological state tends to stabilize.

Answer 2

Set point

Question 3

Self-adjusting mechanism by the internal system

Answer 3

Feedback regulation

Question 4

Two types of feedback regulation

Answer 4

Positive and negative feedback regulation

Question 5

What are the three mechanisms of regulation?

Answer 5

Osmoregulation, Thermoregulation, and chemical regulation

Question 6

What is positive feedback regulation?

Answer 6

Regulation that acts to speed up the direction of change.

Question 7

What is negative feedback regulation?

Answer 7

Regulation that acts to reverse the direction of change to maintain the set point.

Question 8

Which feedback regulation is the most common?

Answer 8

Negative feedback regulation

Question 9

Name and explain the 3 types of osmoregulation solutions

Answer 9

1.Hypertonic solution- The solution outside the cell is more concentrated than the inside of the cell. Water will move out of the cell by osmosis, causing it to shrink.

2. Isotonic solution- The solution inside the cell has the same concentration as the outside of the cell. Water will move in and out of the cell at an equal rate.
3. Hypotonic solution- The solution outside of the cell has a lower concentration than the inside of the cell. Water will move into the cell by osmosis, sometimes causing it to burst.

Question 10

Name the six classes of enzymes.

Answer 10

1.Oxidoreductases
2. Transferases
3.Hydrolases
4.Lyases
5.Isomerases
6.Ligases

Question 11

Explain what oxidoreductases catalyze

Answer 11

They catalyze oxidation-reduction reactions, which involves the loss or gain of protons.

Question 12

Explain what reactions do transferases catalyze

Answer 12

They catalyze the transfer of a C-, N-, or P- containing groups.

Question 13

Explain which reactions do hydrolases catalyze

Answer 13

Catalyze cleavage of bonds by addition of water.

Question 14

What do lyases catalyze

Answer 14

Catalyze the cleavage of C-C, C-S and certain C-N bonds.

Question 15

Which reactions do Isomerases catalyze?

Answer 15

Catalyze the racemization of optical or geometric isomers.

Question 16

Which reactions do ligases catalyze?

Answer 16

Catalyze the formation of bonds between C and O, S, N coupled to hydrolysis of high energy phosphates.

Question 17

Name 4 catalytic strategies

Answer 17

Covalent catalysis
Acid-base reactions
Catalysis by approximating
Metal ion catalysis

Question 18

Briefly explain the covalent catalysis

Answer 18

In covalent catalysis, the enzymes covalently bond to the substrate as the first step.
The active sites contain a reactive group, that forms a covalent bond with the substrate.
Then, the enzyme goes through a mechanism, eventually breaking down the substrate and reforming itself.

Question 19

What occurs in acid-base reactions of enzyme-substrate?

Answer 19

The enzymes generally use a molecule other than water to donate or accept protons as a nucleophile.

Question 20

Briefly explain catalysis by approximation

Answer 20

The close proximity of two substrates can increase the rate of reaction between the two.
Generally, when two molecules combine to become one entropy decreases.
An enzyme that brings the two molecules together decreases the entropy.
This increase in rate is similar to increasing the concentration of the reactants.

Question 21

Briefly explain metal ion catalysis

Answer 21

Metal ions can directly facilitate the formation of bonds.
They are electrophilic and can also act to stabilize the charges on the intermediates in the reaction.

Question 22

What are holoenzymes, and differentiate between holoenzymes and apoenzymes.

Answer 22

Holoenzymes are the enzymes that require molecules other than proteins for enzymic activity.

Holoenzyme- is active with its nonprotein compenent.
Apoenzyme- is inactive without its nonprotein component.

Question 23

Name three factors that affect enzyme function

Answer 23

-Substrate concentration
-Temperature
-pH

Question 24

By definition, what is Km?

Answer 24

Km is the substrate concentration at which the velocity is half of the maximum velocity.

Question 25

Name and describe the two types of inhibitor.

Answer 25

Irreversible inhibitors- binds to enzyme through covalent bonding.
Reversible inhibitors- binds to the enzyme through non-covalent bonding.

Question 26

Name two types of reversible inhibitors

Answer 26

Competitive and non-competitive

Question 27

Briefly explain the two types of reversible inhibition and how they affect Vmax and Km.

Answer 27

Competitive inhibition- the inhibitor binds to the active site of the enzyme, preventing the substrate from binding.
In competitive inhibition Km increases while Vmax remain the same.

Non-competitive inhibition- the inhibitor binds to a different site ( allosteric site) other than the active site of the enzyme, changing the conformation of the active site.
In non-competitive inhibition the Vmax decreases while Km remains the same.

Question 28

Name and explain the two types of allosteric inhibition.

Answer 28

Negative feedback loop, allosterically inhibits the production of a substrate.

Positive feedback loop, allosterically increases the production of a substrate by acting as a cofactor or coenzyme.