Glycolysis_Flashcards

Question 1

What is glycolysis?

Answer 1

A 10-step enzyme-catalyzed process that converts glucose into pyruvate.

Question 2

Where does glycolysis occur?

Answer 2

In the cytosol of most differentiated cells.

Question 3

What is the net ATP gain from glycolysis?

Answer 3

2 ATP per glucose molecule.

Question 4

What are the two main stages of glycolysis?

Answer 4

Hexose stage (ATP-consuming) and triose stage (ATP-generating).

Question 5

Which cofactor is reduced in glycolysis?

Answer 5

NAD+ is reduced to NADH.

Question 6

What enzyme catalyzes Step 1 of glycolysis?

Answer 6

Hexokinase.

Question 7

What happens in Step 1 of glycolysis?

Answer 7

Glucose is phosphorylated to glucose-6-phosphate.

Question 8

Which enzyme catalyzes Step 2?

Answer 8

Glucose-6-phosphate isomerase.

Question 9

What is the function of phosphofructokinase-1 (PFK-1) in Step 3?

Answer 9

It phosphorylates fructose-6-phosphate, committing it to glycolysis.

Question 10

Which enzyme catalyzes Step 4, and what does it do?

Answer 10

Aldolase; it splits fructose-1,6-bisphosphate into DHAP and G3P.

Question 11

What enzyme converts DHAP to G3P in Step 5?

Answer 11

Triose phosphate isomerase.

Question 12

What type of reaction occurs in Step 6, catalyzed by G3P dehydrogenase?

Answer 12

A redox reaction where NAD+ is reduced to NADH.

Question 13

Which enzyme catalyzes Step 7 and what does it produce?

Answer 13

Phosphoglycerate kinase; produces ATP.

Question 14

What type of reaction occurs in Step 8, catalyzed by a mutase?

Answer 14

A phosphoryl shift within the molecule.

Question 15

What is formed in Step 9, catalyzed by enolase?

Answer 15

Phosphoenolpyruvate (PEP), a high-energy intermediate.

Question 16

What enzyme catalyzes the final step of glycolysis?

Answer 16

Pyruvate kinase.

Question 17

What is the final product of glycolysis?

Answer 17

Pyruvate.

Question 18

What is the main regulatory enzyme of glycolysis?

Answer 18

Phosphofructokinase-1 (PFK-1).

Question 19

What activates PFK-1?

Answer 19

AMP and fructose-2,6-bisphosphate.

Question 20

What inhibits PFK-1?

Answer 20

ATP and citrate.

Question 21

How is hexokinase regulated?

Answer 21

Inhibited by glucose-6-phosphate (feedback inhibition).

Question 22

How is pyruvate kinase regulated?

Answer 22

Activated by fructose-1,6-bisphosphate; inhibited by ATP.

Question 23

What is the Pasteur effect?

Answer 23

Glycolysis slows in the presence of oxygen.

Question 24

What are the metabolic fates of pyruvate?

Answer 24

Acetyl-CoA (aerobic), lactate (anaerobic), ethanol (fermentation).

Question 25

Which enzyme converts pyruvate to lactate?

Answer 25

Lactate dehydrogenase.

Question 26

What process converts pyruvate to acetyl-CoA?

Answer 26

Pyruvate decarboxylation by pyruvate dehydrogenase.

Question 27

What enzyme catalyzes ethanol fermentation?

Answer 27

Alcohol dehydrogenase.

Question 28

What is the Cori cycle?

Answer 28

Lactate recycling between muscles and liver.

Question 29

How does fructose enter glycolysis?

Answer 29

Converted to G3P via fructokinase and aldolase.

Question 30

How does galactose enter glycolysis?

Answer 30

Converted to glucose-6-phosphate.

Question 31

How does mannose enter glycolysis?

Answer 31

Converted to fructose-6-phosphate.

Question 32

What is gluconeogenesis?

Answer 32

Biosynthesis of glucose from non-carbohydrate sources.

Question 33

Where does gluconeogenesis occur?

Answer 33

Mostly in the liver and kidney cortex.

Question 34

What are the three irreversible steps in glycolysis?

Answer 34

Steps catalyzed by hexokinase, PFK-1, and pyruvate kinase.

Question 35

Which enzyme converts pyruvate to oxaloacetate in gluconeogenesis?

Answer 35

Pyruvate carboxylase.

Question 36

Which enzyme converts oxaloacetate to PEP?

Answer 36

PEP carboxykinase.

Question 37

Which enzyme bypasses PFK-1 in gluconeogenesis?

Answer 37

Fructose-1,6-bisphosphatase.

Question 38

Which enzyme bypasses hexokinase in gluconeogenesis?

Answer 38

Glucose-6-phosphatase.

Question 39

What is the pentose phosphate pathway?

Answer 39

An alternative glucose metabolism pathway producing NADPH and ribose-5-phosphate.

Question 40

What are the two stages of the PPP?

Answer 40

Oxidative (NADPH production) and non-oxidative (sugar interconversion).

Question 41

What is the main enzyme of the oxidative phase?

Answer 41

Glucose-6-phosphate dehydrogenase.

Question 42

What is the function of transketolases and transaldolases?

Answer 42

Transfer carbon groups between sugars.

Question 43

Which cofactor does transketolase require?

Answer 43

Thiamine pyrophosphate (TPP).

Question 44

How many ATPs are produced in glycolysis per glucose?

Answer 44

4 ATP (gross), 2 ATP (net).

Question 45

How many NADH molecules are produced per glucose?

Answer 45

2 NADH.

Question 46

How many ATPs can be generated per NADH in the electron transport chain?

Answer 46

Around 2.5 ATP.

Question 47

Why is glycolysis essential for red blood cells?

Answer 47

It is their only source of ATP.

Question 48

How is glycolysis linked to the citric acid cycle?

Answer 48

Pyruvate is converted to acetyl-CoA.

Question 49

What is substrate-level phosphorylation?

Answer 49

ATP generation without the electron transport chain.

Question 50

Why is glycolysis one of the oldest metabolic pathways?

Answer 50

It is anaerobic and found in nearly all living organisms.