Metabolic regulation

Question 1

glucose and intracellular ATP maintaine at ___mM to maintain homeostasis

Answer 1

5

Question 2

Hexokinase is an ____which catalyze the same reaction although they have slightly different properties. Made from different genes with diff regulatory aspects.

Answer 2

isoenzyme

Question 3

ATP, ADP and AMP bind to ___enzymes and change their activity level. They are examples of ____modifiers

Answer 3

regulatory; allosteric

Question 4

Covalent modification is

Answer 4

phosphorolation

Question 5

What is a futile pathway

Answer 5

ATP is hydrolyzed and nothing is gained when glycolyis and gluconeogenis is happening at the same time. So they are reciprocally regulated

Question 6

Glucose gets into cell via ___

Answer 6

GLUT 4

Question 7

GLUT 4 is ___dependent

Answer 7

insulin; otherwise sequestered internally in vesicles

Question 8

What are 3 points of regulation for glycolysis

Answer 8

1. Hexokinase
2. Phosphofructokinase 1
3. Pyruvate kinase

Question 9

What are 3 points of regulation for gluconeogenesis

Answer 9

1. Glucose 6-phosphatase
2. Fructose-1, 6-bisphosphatase
3. Pyruvate carboxylase + PEP carboxykinase

Question 10

Glucokinase is liver specific____

Answer 10

isozyme; will forgoe glucose to make sure brain has enough.

Question 11

Hexokinase 4 is sequestered in ____when glucose concentration is low.

Answer 11

nucleus. Cant encounter glucose and phosphorolate it so its kept in cell.

Question 12

When glucose levels are ____ it binds to hexokinase 4 and releases it from the nucleus so it can start phosphorolating glucose so that it can be stored as glycogen

Answer 12

high

Question 13

PFK 1 in glycolysis is an ____regulator

Answer 13

allosteric

Question 14

High [ATP] and [citrate] allosterically signal that energy needs are met and inhibit:

Answer 14

PFK-1

Question 15

High [ADP] and [AMP] allosterically signal need for ATP production and activate ____ and inhibit ___

Answer 15

PFK-1; FBPase-1

Question 16

In the liver, the most important allosteric regulator of PFK-1 is _____ which is synthesized by _____

Answer 16

fructose, 2-6 bisphosphate; PFK-2

Question 17

Glycogen stores in muscle can’t help maintain blood glucose levels bc it is never:

Answer 17

released. Doesn’t have glucose 6 phosphatase. Only uses glycogen for itself

Question 18

Muscles have _____ receptors but no ____receptors; therefore it does not produce the enzymes for gluconeogenesis.

Answer 18

epinephrine; glucagon

Question 19

What are the 3 principle hormones of fuel metabolixm

Answer 19

1. insulin: fed
2. glucagon: hungry
3. epinephrine: terrified

Question 20

Where does epinephrine come form

Answer 20

adrenal medulla; its actually a catacholamine

Question 21

What is a phenol ring with two hydroxyl groups called

Answer 21

catecolamine. Derived directly from aa - tyrosine; have cell membrane associated receptors and trigger a second messenger

Question 22

What is the classical second messenger

Answer 22

cyclic AMP

Question 23

Where does glucagon come from

Answer 23

alpha cells of pancreas–>islets of Langerhaans

Question 24

Pancreas has ___ and ___ functions

Answer 24

exocrine: digestive enzymes
endocrine: releases proteins into bloodstream so it can go throughout the body

Question 25

Beta cells make

Answer 25

insulin

Question 26

Glucagon is a ____hormone

Answer 26

protein

Question 27

What are the targets of glucagon and epinephrine

Answer 27

Use cyclic amp signaling to change metabolic activity.

Question 28

What is a serpentine receptor

Answer 28

External ligand binding to receptor activates an intracellular GTP binding protein which regulates an enzyme that generates an intracellular second messenger. Go back and forth across cell membrane and when hormone binds it activates G protein

Question 29

What are the 5 proteins involved in epinephrine and glucagon signaling

Answer 29

1. beta adrenergic receptor/glucagon receptor 2. Gs protein 3. adenylate cyclase 4. protein kinase A 5. cyclic nucletodie phosphodiesterase

Question 30

1. Epeniphrine binds its specific receptor -->changes conformation of receptor site and G protein. When receptor binds it knocks off ___ and GTP associates. Alpha subunit loses affinity for its receptor and moves into cell membrane and binds to target enzyme: ______GDP falls off and GTP binds. Now has high affinity for target enzyme.

Answer 30

GDP; adenylate cyclase

Question 31

What is adenylate cyclase

Answer 31

the enzyme that converts ATP to cyclic AMP

Question 32

Protein Kinase A becomes activated by ____and changes metabolic activity of all of its protein targets by:

Answer 32

cyclic AMP; phosphorlation

Question 33

What are ways to self limit this process?

Answer 33

1. G protein has inherent GTPase function: hydrolyze GTP, converts it to GDP which now has affinity for the receptor and its beta and gamma subunits. Moves back into its original position. 2. cAMP doesnt hang around all day. Cyclic nucleotide phosphodiesterase hydrolizes cAMP and inactivates it

Question 34

cAMP phosphodiesterase is inhibited by:

Answer 34

caffeine and theophylline

Question 35

How is protein Kinase A activated; what does it catalyze

Answer 35

cAMP; catalyzes the phosphorylation of target proteins

Question 36

Insulin DOES NOT produce ____as a secondary messenger

Answer 36

cAMP

Question 37

What are C peptides indicative of

Answer 37

diagnostic tool that tells you if your body makes natural insulin and differentiates between Type 1 and Type 2 diabetes

Question 38

Which aa form disulfide bonds?

Answer 38

cysteine

Question 39

Insulin receptors come from:

Answer 39

receptor tyrosine kinases | "RTK"; cell signaling proliferation and growth

Question 40

3 aa that have hydroxyl groups:

Answer 40

1. serine 2. threonine 3. tyrosine

Question 41

What do insulin receptors do

Answer 41

Auto phosphoralates its own tyrosine receptors that activates receptor and other targets.

Question 42

How does insulin signaling I occur

Answer 42

1. Insulin binds to receptor and autophosphorolates on its own tyrosine residues 2.

Question 43

Growth factors cause

Answer 43

cell proliferation

Question 44

Insulin is a potent ___factor that activates the ____pathway

Answer 44

growth; MAPK --> regulate transcription factors needed for cell division

Question 45

What is Ras

Answer 45

G protein; when GDP bound its inactive when GTP bound it activates Raf 1 Kinase that starts MAPK cascade that turns on genes for cell division.

Question 46

Ras is commonly _____in different cancers.

Answer 46

mutated. -->in GTPase domain; the part that is meant to turn off the singal. Cell keeps dividing

Question 47

IRS 1 can interact with

Answer 47

multiple targets.

Question 48

How does insulin signaling II occur

Answer 48

PKB activated by IRS1, which leads to phosphoprotein phosophatase 1 which takes phosophate group off that protein kinase A phosphorolates.

Question 49

What is the major modulator for PFK-1

Answer 49

Fructose 2,6 bisphosphate; allosterically increases PFK-1 affinity for F-6-P (fructose 6 phosphate); decreases PFK-1 affinity for ATP and citrate

Question 50

PFK-1 activation favors

Answer 50

glycolysis

Question 51

Active PFK-2, means there is a high amount of Fructose, 2-6 BP which activates ____ and favors___

Answer 51

PFK1; glycolysis

Question 52

If PFK-2 gets phosphorolated it becomes ___

Answer 52

inactivated; glycolysis would stop and gluconeogenesis would happen

Question 53

PFK-2 is a ____enzyme

Answer 53

bifunctional; also takes phosphate back off.

Question 54

What does pyruvate kinase do in glycolysis

Answer 54

Converts PEP to pyruvate and makes ATP; this is the first step thats irreversible in gluconeogenesis

Question 55

If ATP levels are high glycolysis:

Answer 55

slows down

Question 56

if ADP and AMP are high

Answer 56

we will need to make more ATP

Question 57

Liver has special isoenzyme of pyruvate kinase that is inactivated by_____. When blood glucose falls, ______is secreted. _____ levels increase. ____is activated. PFK-2 is phosphorolated and inactivated. _______ decreases; _____ activity decreases. Glycolysis slows down. Pyruvate kinase is _____ and inactivated.

Answer 57

PKA phosphorolation; glucagon; cAMP; PKA is activated; Fructose 2, 6 BP; PFK-1; phosphorolated.

Question 58

Gluconeogenesis is favored in the

Answer 58

liver

Question 59

pyruvate carboxylase is activated by

Answer 59

acetyl coA

Question 60

High levels of insulin blocks the transcription of

Answer 60

PEPCK; thus reducing gluconeogenesis.