Glucose metabolism

Question 1

What is the regulatory enzyme of glycolysis ?

Answer 1

PFK-1

Question 2

What is the regulatory enzyme of gluconeogenesis?

Answer 2

FBPase-1

Question 3

Is glycolysis catabolic or anabolic in brain? Aerobic or anaerobic?

Answer 3

aerobic catabolic

Question 4

Is glycolysis catabolic or anabolic in liver? Aerobic or anaerobic?

Answer 4

aerobic anabolic

Question 5

Is glycolysis catabolic or anabolic in muscle? Aerobic or anaerobic?

Answer 5

can be anaerobic or aerobic catabolic

Question 6

Is glycolysis catabolic or anabolic in RBC? Aerobic or anaerobic?

Answer 6

anaerobic catabolic

Question 7

What is ultimate end product of anabolic glycolysis?

Answer 7

pryuvate to acetyl-CoA to fatty acid synthesis

Question 8

overall formula for aerobic glycolysis

Answer 8

1 glucose => 2 pyruvate + 2 ATP + 2 NADH

Question 9

overall formula for anaerobic glycolysis

Answer 9

1 glucose => 2 lactate + 2 ATP

Question 10

How is PFK-1 modulated in liver?

Answer 10

F-2,6-bisphosphate phosphorylates to activate

F-2,6-bP is upregulated by insulin

Question 11

How is PFK-1 modulated in muscle?

Answer 11

ratio of ATP/AMP regulates PFK-1

Question 12

hepatic reciprocal regulation

Answer 12

insulin activates F-2,6-bP to phosphorylate PFK-1 and increase glycolysis

when F-2,6-bP is absent, FBP-1 is turned on and gluconeogenesis is turned on

Question 13

muscle control of glycolysis

Answer 13

high AMP = activate PFK-1 (ratio of ATP to AMP is decreasing)

Question 14

What does high ATP activate?

Answer 14

FBP-1

*do not need to run more glycolysis

Question 15

citric acid cycle (TCA)

Answer 15

oxidizes acetyl-CoA to FADH2 and NADH

Question 16

Does TCA require O2?

Answer 16

not directly

however, the ETC does require O2. If ETC can’t run due to low O2 conditions, then NAD+ and FAD+ will not be reformed and TCA will be inhibited

Question 17

fatty acid oxidation and gluconeogenesis

Answer 17

gluconeogenesis uses glycerol from FA oxidation

Question 18

What produces lactate?

Answer 18

the reduction of pyruvate

Question 19

Where is F-2,6-bP found?

Answer 19

exclusively in the liver

Question 20

4 components of metabolic syndrome

Answer 20

1) dyslipidemia
2) obesity
3) insulin resistance
4) HTN

Question 21

What should triglycerides be under?

Answer 21

150

Question 22

What is leading cause of mortality for individuals with metabolic syndrome?

Answer 22

heart attack

Question 23

What 2 pathways does the Cori cycle connect? How?

Answer 23

anaerobic glycolysis and gluconeogenesis

lactate from anaerobic glycolysis makes glucose in gluconeogenesis (pyruvate intermediate)

glucose from gluconeogenesis makes lactate in anaerobic glycolysis (pyruvate intermediate)

Question 24

3 sources of carbon for gluconeogenesis

Answer 24

lactate, glycerol, and amino acids

Question 25

What are 2 main amino acids for gluconeogenesis?

Answer 25

alanine and glutamine

Question 26

Where is GLUT-1 found?

Answer 26

most mammalian cells

Question 27

Where is GLUT-2 found?

Answer 27

liver, pancreatic B-cells, renal tubules, intestines

Question 28

Where is GLUT-3 found?

Answer 28

brain and placenta

Question 29

Where is GLUT-4 found?

Answer 29

muscle and adipose, regulated by insulin

Question 30

Why does GLUT-2 have a lower affinity for glucose? (liver + intestine)

Answer 30

in liver, want to uptake glucose for storage, so want to uptake glucose when there are higher amounts in intestine, glucose amounts will be high after a meal, so low affinity works there too

Question 31

what is most excess glucose stored as?

Answer 31

mostly triglycerides *more energy than glycogen

Question 32

Why does low affinity for GLUT-2 work for pancreatic B-cells?

Answer 32

when glucose levels are high the transporter will work this signals insulin release only when there are high levels of blood glucose

Question 33

Why is C-peptide useful?

Answer 33

can see how much insulin is produced insulin has a shorter half-life, so C-peptide is easier to measure

Question 34

General steps of insulin release (6 steps)

Answer 34

1) glucose enters B-cell through GLUT-2 2) go through glycolysis + ATP levels rise 3) K+ channels close 4) membrane depolarization 5) Ca2+ channels open 6) insulin released

Question 35

What enzymes triggers the GLUT-4 receptor expression?

Answer 35

PI3 kinase

Question 36

where does ketongenesis occur?

Answer 36

in the liver

Question 37

what regulates ketonegenesis?

Answer 37

insulin decreases in T1DM, no insulin to downregulate ketonegenesis which can lead to ketoacidosis

Question 38

Where does gluconeogensis occur?

Answer 38

liver and kidneys

Question 39

Effects of ESRD on metabolism

Answer 39

can cause severe hyperglycemia if insulin is not being produced at all by the kidneys

Question 40

3 times when insulin resistance is normal

Answer 40

1) pregnancy (want high blood sugar for baby) 2) puberty 3) steriod / glucocortiod use

Question 41

Is insulin resistance always T2DM?

Answer 41

No! most of the time not

Question 42

What causes T2DM?

Answer 42

insulin resistance combined with beta cells inability to make more insulin to overcome resistance

Question 43

Diabetic fasting glucose level

Answer 43

> 126 mg/dL

Question 44

Normal fasting glucose level

Answer 44

< 100 mg/dL

Question 45

Diabetic HA1c

Answer 45

> 6.5 %

Question 46

Normal HA1c

Answer 46

< 5.6 %

Question 47

diabetic 2-hour oral glucose tolerance

Answer 47

> 200 mg/dL

Question 48

normal 2-hour oral glucose tolerance

Answer 48

< 140 mg/dL