L1 - Glycolysis and PPP and their Role in Metabolism

Question 1

Which enzyme(s) convert pyruvate to…

1) acetyl CoA
2) alanine
3) oxaloacetate
4) lactate

Answer 1

1) pyruvate dehydrogenase complex
2) alanine aminotransferase aka alanine transaminase (ALT)
3) pyruvate carboxylase
4) lactate dehydrogenase

Question 2

Glucose transporters work through which mechanism?

Answer 2

facilitated diffusion

Question 3

Which molecule does arsenate inhibit the formation of?

Answer 3

1,3-bisphosphoglycerate

Question 4

Where are glycolytic enzymes present in the cell?

Answer 4

cytosol

Question 5

What is the enzyme transketolase used as a marker for? What vitamin does it require?

Answer 5

1) thiamine concentration

2) thiamine, vitamin B1

Question 6

What are the four fates of pyruvate?

Answer 6

1) alanine
2) acetyl CoA
3) lactate
4) oxaloacetate

Question 7

Which two metabolites increase activity of PFK-1?

Answer 7

1) AMP

2) fructose 2,6-bisphosphate

Question 8

Glucokinase has a _____ Km and a ______ Vmax. It is found in the ______. as well as the _________.

Answer 8

1) high
2) high
3) liver
4) beta cells in the pancreas

Question 9

Hexokinase facilitates which reaction? PFK-1 facilitates which reaction?

Answer 9

1) glucose –> glucose 6-phosphate

2) fructose 6-phosphate –> fructose 1,6-bisphosphate

Question 10

Hexokinase has a _____ Km and a _______ Vmax. Where is it found in the body? What does it function as?

Answer 10

1) low
2) low
3) functions as a high-affinity glucose transporter

Question 11

Fructose 2,6-bisphosphate is not a proper metabolite of glycolysis, so why is it relevant?

Answer 11

It acts as an allosteric activator of PFK-1. Its levels are correlated with glylcolytic activity because it is byproduct of the formation of fructose 1,6-bisphosphate made by PFK-2

Question 12

The conversion of PEP into pyruvate is catalyzed by which enzyme?

Answer 12

pyruvate kinase

Question 13

What four tissues does the PPP occur primarily in? Why?

Answer 13

1) liver
2) adipocytes
3) adrenal cortex
4) gonads
Because they are very active in reductive biosynthesis

Question 14

GLUT-4 is an insulin-_________ glucose transporter that is found in ________ and __________.

Answer 14

1) sensitive
2) adipose
3) skeletal muscle

Question 15

Glucokinase acts as what in terms of glucose metabolism?

Answer 15

glucose sensor, it picks up on high levels of glucose in the blood

Question 16

What molecule inhibits glyceraldehyde 3-phosphate DHG?

Answer 16

arsenate

Question 17

How do we use the Warburg effect clinically?

Answer 17

In PET scans you can localize a tumor by using fluorodeoxyglucose, a radiocompound of glucose

Question 18

How does the muscle clear the lactate that is made via exercise?

Answer 18

By the Cori cycle via the liver

Question 19

The conversion of pyruvate into lactate produces what?

Answer 19

NAD+

Question 20

What is the name of the glucose transporter in the liver? What is special about it?

Answer 20

GLUT2, it is bidirectional

Question 21

Fructose 1,6-bisphate activates pyruvate kinase. What is this an example of?

Answer 21

Feed-forward activation

Question 22

What is the name of the protein that takes up glucose from the GI? What is different about it as compared to GLUTs?

Answer 22

SGLT-1

It is a sodium-glucose cotransporters rather than a glucose-only transporter

Question 23

Pyruvate is shuttled where in anaerobic conditions? Where does it go if it is in aerobic conditions?

Answer 23

anaerobic - liver

aerobic - mitochondria

Question 24

What element determines which direction the reactions related to pyruvate will go?

Answer 24

NADH/NAD+ ratio

Question 25

What disorder is the result of an inherited mutation of glucokinase?

Answer 25

MODY-2, maturity-onset diabetes of the young, type 2

Question 26

NADPH is needed in the body for synthesis of _______ and ______ as well as ________ metabolism.

Answer 26

1) fatty acid
2) steroid
3) drug

Question 27

The first and third step of glycolysis use which enzymes? Why are they important?

Answer 27

1) hexokinase and PFK-1, respectively

2) irreversible steps which are regulated

Question 28

What effect does insulin have on PFK-2 activity?

Answer 28

Increased insulin leads to increased PFK-2 activity.

Question 29

Where can GLUT1 and GLUT3 be found?

Answer 29

GLUT1 - BBB

GLUT3 - neurons

Question 30

What is the effect whereby cancer cells increase their uptake and metabolism of glucose?

Answer 30

Warburg effect