Dr Quan Exam 1 Study Guide

Question 1

Most critical function of an enzyme

Answer 1

Accelerate reactions by millions fold

Question 2

Optimum temperature for enzymes

Answer 2

37 degrees C

Question 3

Optimum pH for enzymes

Answer 3

~7

Pepsin exception: 1.5-2

Question 4

Composition of complex enzyme

Answer 4

Apoenzyme (protein part) and Cofactor (Prosthetic group or Coenzyme)

Question 5

Catalyze oxidation-reduction reactions

Answer 5

Oxidoreductase

Question 6

Catalyzes group transfers

Answer 6

Transferase

Question 7

Catalyzes hydrolysis rxns where water is acceptor of transferred group

Answer 7

Hydrolase

Question 8

Catalyze isomerization rxns (D to L, L to D)

Answer 8

Isomerase

Question 9

Catalyze the lysis of substrate, generating a double bond in a nonhydrolytic, nonoxidative elimination.

Answer 9

Lyases

Question 10

Catalyze joining of two substrates and requires ATP (energy)

Answer 10

Ligase

Question 11

Specific region of enzyme where substrate molecule is bound

Answer 11

Active Site

Question 12

Enzyme active site only able to accept specific substrate type

Answer 12

Lock and Key Theory (Fischer Theory)

Question 13

Enzyme acts only on one substrate

Answer 13

Absolute Specificity

Question 14

Enzyme acts on different substrates that have same bond type

Answer 14

Relative Specificity

Question 15

Enzyme Activity Definition

Answer 15

1 international unit (IU) of enzyme catalyzes conversion of 1 micromol of substrate to product per minute

Question 16

Km (Michaelis Constant) definition

Answer 16

Substrate concentration @ 1/2 Vmax

Question 17

Reversible Inhibitors

Answer 17

Can rapidly dissociate

Weak, noncovalent interaction

Question 18

Irreversible Enzyme Inhibition

Answer 18

Slow dissociation of EI complex

Tightly bound

Question 19

Competitive Inhibitor

Answer 19

Competes with substrate at active site.

Km increased, Vmax unchanged

Question 20

Non-competitive inhibitor

Answer 20

Binds to enzyme site different from active site.

Km unchanged, Vmax decreased

Question 21

Uncompetitive Inhibitors

Answer 21

Binds to ES complex (not free enzyme)

Decreases both Km and Vmax

Question 22

Positive (stimulating) or Negative (inhibiting) regulation of enzyme. Site different from active site.

Answer 22

Allosteric Regulation

Question 23

Covalent attachment to modify activity (EX: Phosphorylation)

Answer 23

Reversible Covalent

Question 24

Multiple forms of an enzyme which differ in structure/genes but catalyze same reaction

Answer 24

Isoenzymes

Question 25

Enzymes are synthesized as inactive precursors (zymogens) and activated by cleavage. (EX: Insulin)

Answer 25

Proteolytic Activation

Question 26

Channeling of reactants between active sites

Answer 26

Metabolic Channeling

Question 27

Gycolysis starts and ends where?

Answer 27

Glucose -> lactate

Question 28

Glucose generates what five things?

Answer 28

1. ATP 2. Glycogen 3. Ribose 4. Lipid molecules 5. NADPH

Question 29

Glycolysis has what two stages?

Answer 29

Investment and yield

Question 30

Glucose can be trapped in a cell in the form of?

Answer 30

Glc-6-P

Question 31

Rate limiting enzyme of glycolysis

Answer 31

PFK-1

Question 32

What two things catalyze the yield of ATP in glycolysis?

Answer 32

PGK and pyruvate kinase

Question 33

Glycolysis ATP account

Answer 33

Use 2 ATP to generate 4 ATP. Net gain of 2 ATP

Question 34

Pyruvate can be transformed to _______ to regenerate ______

Answer 34

Lactate NAD+

Question 35

Hexokinase can be inhibited by

Answer 35

Glc-6-P

Question 36

PFK-1 can be inhibited by _____ and activated by _____

Answer 36

ATP AMP

Question 37

Pyruvate Kinase can be activated by ______

Answer 37

Fructose-1,6-BP

Question 38

Pentose phosphate pathway is important for the generation of _____ and _____

Answer 38

NADPH Ribose

Question 39

Structure of glycogen

Answer 39

C24 H42 O21

Question 40

What is used as the building block for glycogen?

Answer 40

UDP-glucose

Question 41

What extends the chain of glycogen?

Answer 41

Glycogen synthase

Question 42

What initiates glycogen synthesis?

Answer 42

Glycogenin

Question 43

What catalyzes the breakdown of glycogen?

Answer 43

Glycogen Phosphorylase

Question 44

What can be used to treat diabetes?

Answer 44

Inhibition of glycogen phosphorylase

Question 45

What enzyme stimulates glycogenolysis?

Answer 45

Glucagon

Question 46

What two things increase the activity of glycogen phosphorylase?

Answer 46

Epinephrine and glucagon

Question 47

What is basically the reverse of glycolysis?

Answer 47

Gluconeogenesis

Question 48

Where does the TCA cycle occur?

Answer 48

Eukaryotic cells -> mitochondrial matrix

Question 49

Two major functions of TCA cycle:

Answer 49

1. Increase cell's ATP-producing potential by generated reduced electron carriers NADH and ubiquinone 2. Provide cell with a variety of metabolic precursors.

Question 50

What two things are derived from pyruvate?

Answer 50

Acetyl-CoA and Oxaloacetate

Question 51

What catalyzes the synthesis of acetyl-CoA?

Answer 51

Pyruvate dehydrogenase

Question 52

The 4 oxidative enzymes in the TCA cycle:

Answer 52

1. Isocitrate DH 2. AKG DH 3. Succinate DH 4. Malate DH

Question 53

Pyruvate DH is negatively regulated by:

Answer 53

1. ATP 2. Acetyl-CoA 3. NADH