Brenda - Glycolysis

Question 1

Define glycolysis
(3)

Answer 1

Splitting of sugar

The universal pathway for glucose breakdown

Anaerobic

Question 2

Why is glycolysis necessary?
(3)

Answer 2

To produce energy in the form of ATP
and NADH (energy carriers)

To convert glucose into pyruvate for the Krebs cycle

To generate precursors for other pathways e.g. serine synthesis

Question 3

How many molecules of ATP are made by glycolysis?

Answer 3

4 ATP out

Question 4

How many molecules of ATP are needed for glycolysis to occur?

Answer 4

2 ATP in

Question 5

How many carbons are in glucose?

Answer 5

6C

Question 6

What is NADH+ +H+ before collecting 2 electrons?

Answer 6

NAD+

Question 7

How many molecules of NAD+ are needed for glycolysis?

Answer 7

2NAD+

Question 8

What is the fate of the 2NADH and H+ produced by glycolysis?

Answer 8

It’s used to make ATP in the mitochondria

Question 9

Overall, what is glucose broken into by glycolysis?

Answer 9

2 x Pyruvate (3C)

Question 10

Where does glycolysis occur in eukaryotes?

Answer 10

In the cytosol

Question 11

After glycolysis in the cytosol, where does further oxidation occur?

Answer 11

In the mitchondria

Question 12

Write a note on reaction 1
(6)

Answer 12

Glucose is converted into Glucose 6 phosphate

Catalysed by hexokinase

Energy needed in the form of ATP (ATP -> ADP)

Mg2+ is required

Hexokinase is inhibited by G-6-P

Liver hexokinase is not inhibited by G-6-P which allows the liver to adjust the rate of glucose utilisation in response to blood glucose levels

Question 13

What inhibits hexokinase?

Answer 13

G-6-P

Question 14

What does liver hexokinase do?

Answer 14

Liver hexokinase is not inhibited by G-6-P which allows the liver to adjust the rate of glucose utilisation in response to blood glucose levels

Question 15

Write a note on reaction 2
(3)

Answer 15

The isomerisation of G6P

Glucose-6-phosphate is converted into Fructose-6-phosphate

Catalysed by phosphoglucoisomerase

Question 16

Write a note on reaction 3
(7)

Answer 16

Fructose-6-phosphate is converted into Fructose bisphosphate

Catalysed by phosphofructokinase (PFK)

Needs energy in ATP (ATP ->ADP)

Phosphorylation reaction

The first step at which glycolysis is regulated

PFK is an allosteric enzyme

Two phosphates are also made

Question 17

Phosphofructokinase is an allosteric enzyme, what does this mean?

Answer 17

The enzyme has another site other than it’s active site

Question 18

What is the enzyme for reaction 2?

Answer 18

phosphoglucoisomerase

Question 19

What is the enzyme for reaction 3?

Answer 19

Phosphofructokinase (PFK)

Question 20

Write a note on reaction 4
(3)

Answer 20

Fructose bis phosphate is converted to DHAP (Dihydroxyacetone phosphate) and G3P (glyceraldehyde-3-phosphate)

Catalysed by aldolase

Cleavage reaction

Question 21

What does DHAP stand for?

Answer 21

Dihydroxyacetone phosphate

Question 22

What does G3P stand for?

Answer 22

Glyceraldehyde-3-phosphate

Question 23

Write a note on reaction 5
(3)

Answer 23

DHAP is converted into G3P

Catalysed by triose phosphate isomerase

An isomerization reaction

Question 24

What is the enzyme for reaction 5?

Answer 24

Triose phosphate isomerase

Question 25

Give the types of the first five reactions of glycolysis

Answer 25

1 = phosphorylation 2 = isomerization 3 = phosphorylation 4 = cleavage 5 = isomerisation

Question 26

Write a note on reaction 6 (4)

Answer 26

Glyceraldehyde 3 phosphate is converted into bisphosphoglycerate Catalysed by glyceraldehyde-3-phosphate dehydrogenase (G3PDH) Generates two NADH Oxidation and phosphorylation

Question 27

What is the catalyst for reaction 6?

Answer 27

glyceraldehyde-3-phosphate dehydrogenase (G3PDH)

Question 28

Write a note on reaction 7 (4)

Answer 28

Bisphosphoglycerate is converted to 3-phosphoglycerate Catalysed by phosphoglycerate kinase Produces 2 ATPs Substrate level phosphorylation reaction

Question 29

What is the enzyme for reaction 7?

Answer 29

Phosphoglycerate kinase

Question 30

How many ATPs are produced by reaction 7?

Answer 30

2 ATP

Question 31

Write a note on reaction 8 (3)

Answer 31

3 Phosphoglycerate is converted into 2 phosphoglycerate Catalysed by phosphoglycerate mutase Isomerisation reaction

Question 32

What is the enzyme for reaction 8?

Answer 32

Phosphoglycerate mutase

Question 33

Write a note on reaction 9 (4)

Answer 33

2 phosphoglycerate is converted into phosphoenolpyruvate (PEP) Catalysed by enolase PEP is a super high energy compound Dehydration reaction

Question 34

What is the enzyme for reaction 9?

Answer 34

Enolase

Question 35

Write a note on reaction 10? (4)

Answer 35

Phosphoenolpyruvate is converted into pyruvate Catalysed by pyruvate kinase Substrate-level phosphorylation Produces 2 ATP

Question 36

What does PEP stand for?

Answer 36

Phosphoenolpyruvate

Question 37

How many ATP molecules are produced by step 10?

Answer 37

2 molecules of ATP

Question 38

How is lactose broken down into pyruvate? (3)

Answer 38

Lactose is a polysaccharide made of glucose and galactose Lactase works on lactose to break it down to it's monosaccharides Glucose enters glycolysis as normal Galactose is then isomerised to form Glucose-6-phosphate which joins the cycle at reaction 2

Question 39

How is sucrose broken down into pyruvate? (4)

Answer 39

Sucrose is a disaccharide made of glucose and fructose Sucrase breaks sucrose down into it's simple sugars Glucose enters glycolysis as normal Fructose is phosphorylated into fructose-6-phosphate which then joins the cycle at reaction 3

Question 40

How is maltose broken down into pyruvate? (2)

Answer 40

Maltose is made of two glucose units Maltase acts on maltose breaking it down into the two glucose molecules which enter the cycle as normal

Question 41

What happens to pyruvate?

Answer 41

Most will be converted to acetyl CoA and oxidised through the TCA cycle

Question 42

What type of reaction is the conversion of pyruvate to acetyl-CoA?

Answer 42

Oxidative decarboxylation

Question 43

What catalyses the oxidative decarboxylation of pyruvate to acetyl-co A?

Answer 43

PDH

Question 44

At what steps is glycolysis regulated?

Answer 44

Reaction 1, 3, 10