Enzymes

Question 1

How many cells does the average adult male have?

Answer 1

37.2 trillion

Question 2

What are enzymes and what do they do?

Answer 2

They are proteins that act as biological catalysts. They speed up the rate of reactions by reducing the activation energy needed for reaction to occur. They are sensitive to temperature and pH.

Question 3

What do enzymes not do?

Answer 3

1. Change or get consumed in a reaction
2. Affect the equilibrium of the reaction
3. Affect thermodynamic parameters (𝚫G,𝚫H,𝚫S)
4. Change spontaneity

Question 4

What is an exergonic reaction?

Answer 4

Releases energy so products will be lower than the reactants.

Question 5

What is an endergonic reaction?

Answer 5

Needs energy so the products will be higher than the reactants.

Question 6

What does an enzyme speed up?

Answer 6

It will speed up both the forward and reverse reaction of the process that it catalyzes. Lowers the activation barrier for reverse reaction too.

Question 7

What is a substrate?

Answer 7

A substance that an enzyme operates on.

Question 8

Where do enzyme-substrate interactions occur?

Answer 8

At the active site

Question 9

What are the two areas that make up the active site?

Answer 9

Binding Site

Catalytic Site

Question 10

Describe the binding site.

Answer 10

It is larger than the catalytic site and is where the substrate interacts with the enzyme through intermolecular forces (hydrogen bonding, dipole-dipole interactions, and London dispersion factors). It positions the substrate properly relative to the catalytic site. Gives enzyme specificity (can only interact with very specific substrate).

Question 11

Describe the catalytic site.

Answer 11

It is the specific place where the reaction is catalyzed.

Question 12

When does the enzyme-substrate complex form?

Answer 12

When the substrate interacts with the active site of an enzyme.

Question 13

What is the Lock and Key Theory?

Answer 13

It proposes that the active site of an enzyme and the substrate fit together like puzzle pieces with no change in the tertiary or quaternary structure. Turned out to be an oversimplification.

Question 14

What is the Induced Fit Model?

Answer 14

It proposes that the enzyme and substrate affect each other. The initial stages of binding induce conformational shifts that allow closer binding and more efficient catalysis.

Question 15

What is a ligand?

Answer 15

Any substance that an enzyme interacts with. Can be a substrate or regulatory molecule.

Question 16

What are the two regulatory molecules?

Answer 16

Orthosteric Regulation

Allosteric Regulation

Question 17

What does an orthosteric regulatory molecule do?

Answer 17

It interacts with the enzymes active site.

Question 18

What does an allosteric regulatory molecule do?

Answer 18

It interacts with other sites on the enzyme that are not the active site.

Question 19

What is the suffix of all enzymes?

Answer 19

-ase

Question 20

What does the highest level category of an enzyme tell us?

Answer 20

It describes the chemical mechanism, not the biological function.

Question 21

What are the 6 highest level categories of enzymes?

Answer 21

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

Question 22

What do oxidoreductases do and what are some examples?

Answer 22

They catalyze oxidation/reduction reactions.

Ex. Alcohol Dehydrogenase, Superoxide Dimutase

Question 23

What do transferases do and what are some examples?

Answer 23

They transfer functional groups between molecules.
Ex. Aspartate Transaminase, Creatine Kinase, DNA
polymerase

Question 24

What do hydrolases do and what are some examples?

Answer 24

They catalyze hydrolysis.
Ex. Angiotensin-Converting Enzyme, Pancreatic Lipase,
Lactase

Question 25

What do isomerases do and what are some examples?

Answer 25

They catalyze isomerization which is the conversion of one isomer to another. Isomers have identical formulas but different structure.
Ex. Ribose-5-Phospate Isomerase

Question 26

What do lyases do and what are some examples?

Answer 26

They sever bonds but do not use hydrolysis.

Ex. Pyruvate Decarboxylase Aconitase

Question 27

What do ligases do and what are some examples?

Answer 27

They join molecules together with covalent bonds.
Ex. Aminoacyl tRNA Synthetase, Glutamine Synthetase,
Pyruvate Carboxylase

Question 28

What does the specific name of an enzyme usually reflect?

Answer 28

Its function

Question 29

What are the two popular types of enzymes that invole phosphate groups?

Answer 29

Phosphatases

Kinases

Question 30

What do Phosphatases do?

Answer 30

They remove phosphate groups from a substrate. Dephosphorylation
(Type of Hydrolase)

Question 31

What do Kinases do?

Answer 31

They add a phosphate group to a substrate. Phosporylation - most likely to occur on Serine, Threonine, and Tyrosine.
(Type of Transferase)

Question 32

What type of enzyme is trypsin?

Answer 32

It is a protease. Proteases are enzymes that break down proteins. They are a type of hydrolase enzyme.

Question 33

What is a way that an enzyme can affect the rate of which a biological chemical reaction can occur?

Answer 33

By reducing the physical distance between reactants and manipulated the acid concentration within a catalytic cleft.

Question 34

What is often necessary for certain reactions to occur?

Answer 34

Altering of the local pH.

Question 35

What is a trick to use when you’re unfamiliar with an enzyme name?

Answer 35

You can conclude that the enzyme acts on or breaks down whatever comes before the “-ase” suffix.