Exam 3 Review

Question 0

What type of reaction is an oxidoreductase reaction?

Answer 0

Oxidation-Reduction

Question 1

What are the different types of cofactors?

Answer 1

Metals

Coenzymes

Question 2

What type of reaction is an transferase reaction?

Answer 2

Group transfer

Question 3

What type of reaction is a hydrolase reaction?

Answer 3

Hydrolysis reaction (transfer of functional groups to water)

Question 4

What type of reaction is a lysase reaction?

Answer 4

Addition or removal of groups to form double bonds

Question 5

What type of reaction is an isomerase reaction?

Answer 5

Isomerization (intramolecular group transfer)

Question 6

What type of reaction is a ligase reaction?

Answer 6

Ligation of two substrates at the expense of ATP hydrolysis

Question 7

What are the 6 types of enzyme reactions?

Answer 7

1) Oxidoreductase
2) Hydrolysis
3) Lyase
4) Isomerase
5) Transferase
6) Ligase

Question 8

What is the Km?

Answer 8

The [substrate] that produces 1/2 Vmax

Question 9

What is the Vmax?

Answer 9

Maximum velocity an enzyme is saturated with substrate

Question 10

When [S] = Km…

Answer 10

Vo = Vmax/2

Question 11

What is Vmax dependent on?

Answer 11

The amount of enzyme used

Question 12

How do you determine the Km from a lineweaver-Burk Plot?

Answer 12

X-intercept = -1/Km

Question 13

How do you determine the Vmax from a lineweaver-Burk Plot?

Answer 13

Y-intercept = 1/Vmax

Question 14

What are Sequential Bisubstrate reactions?

Answer 14

All substrates bind to the enzyme before any product is released

Question 15

What are Double-displacement (ping-pong) Bisubstrate reactions?

Answer 15

One of the products is released before a second substrate binds

Question 16

What is allosteric inhibition?

Answer 16

Binding of an allosteric inhibitor, stabilizing the enzyme in its low-affinity form resulting in little or no activity

Question 17

What is allosteric activation?

Answer 17

Binding of an allosteric activator, stabilizing the enzyme in its high-affinity form resulting in enzyme activity

Question 18

What is the major role of Phosphatases?

Answer 18

Turn off signaling cascades activated by kinases

Question 19

Describe serine proteases

Answer 19

Catalytic triad
Active site for protein cleavage
Serine 195 of chymotrypsin

Question 20

What does a zymogen become an active protease/enzyme?

Answer 20

After cleavage

Question 21

What zymogen/enzyme is found in the stomach?

Answer 21

Pepsinogen/Pepsin

Question 22

What zymogen/enzymes are found in the pancreas?

Answer 22

Chymotrypsinogen/Chymotrypsin
Trypsinogen/Trypsin
Procarboxypeptidase/Carboxypeptidase
Proelastase/Elastase

Question 23

What is the fuel source for the brain under non-starvation conditions?

Answer 23

Glucose

Question 24

What is the only fuel source of RBC’s?

Answer 24

Glucose

Question 25

Stage 1 of glycolysis consists of which enzyme reactions?

Answer 25

1) Phosphorylation
2) Isomerization
3) Phosphorylation

Question 26

Stage 2 of glycolysis consists of which enzyme reactions?

Answer 26

Isomerization/Cleavage

Question 27

How is phosphofructokinase regulated in the liver?

Answer 27

Activated by F-2,6-BP

Inhibited by citrate

Question 28

How is glucokinase regulated in the liver?

Answer 28

Not inhibited by G-6-P

Question 29

Is hexokinase in the liver?

Answer 29

No, glucokinase instead

Question 30

How is pyruvate kinase regulated?

Answer 30

By allosteric effectors and covalent modification

Question 31

What are the whole body needs and daily brain needs of glucose?

Answer 31

Whole body-160g

Brain-120g

Question 32

Is gluconeogenesis a reversal of glycolysis?

Answer 32

NO

Question 33

What are the 3 enzymes of irreversible reactions in glycolysis in the liver & skeletal muscle?

Answer 33

Glucokinase/Hexokinase
Phosphofructokinase
Pyruvate kinase

Question 34

What are the “by-pass” steps used during gluconeogenesis to go around the irreversible glycolysis steps?

Answer 34

Pyruvate carboxylase/Phosphoenolpyruvate carboxykinase
Fructose-1,6-Bisphosphatase
Glucose-6-Phosphatase

Question 35

What is pyruvate converted to in the first step of gluconeogenesis?

Answer 35

Oxaloacetate via Pyruvate carboxylase

Question 36

What must be done for glucose to leave the liver?

Answer 36

Phosphate from glucose-6-phosphate must be cleaved off

Question 37

What determines which pathway (glycolysis/gluconeogenesis) will be most active?

Answer 37

ATP/ADP ratio (energy charge)

Question 38

What process traps glucose-1-phosphate in the cell?

Answer 38

Phosphorolysis

Question 39

UTP binds with glucose-1-phosphate to form _______ in glycogen synthesis.

Answer 39

UDP-glucose

Question 40

During the glycogen synthase step of glycogen synthesis, what type of glycosidic bonds are formed?

Answer 40

alpha 1,4

Question 41

What does branching cause?

Answer 41

Increased solubility

Increased rate of synthesis and degradation

Question 42

Which two hormones can’t cross the membrane?

Answer 42

Glucagon

Epinephrine

Question 43

Where does the CAC take place?

Answer 43

Mitochondria

Question 44

What is the E1 enzyme and what is its prosthetic group?

Answer 44

Pyruvate dehydrogenase component

TPP

Question 45

What is the E2 enzyme and what is its prosthetic group?

Answer 45

Dihydrolipoyl transacetylase

Lipoamide

Question 46

What is the E3 enzyme and what is its prosthetic group?

Answer 46

Dihydrolipoyl dehydrogenase

FAD

Question 47

What is the only step of the CAC that directly yields a high energy compound?

Answer 47

Succinyl CoA —>Succinate

*Succinyl CoA synthetase

Question 48

What other function can excess alpha-ketoglutarate lead to?

Answer 48

Synthesis of amino acids and purine bases