Week eight and nine- Carbohydrate metabolism

Question 1

What molecules are carbohydrates made up of?

Answer 1

Carbon, hydrogen and oxygen

Question 2

What are the classes of carbohydrates?

Answer 2

– Monosaccharides – Disaccharides – Polysaccharides

Question 3

What group are carbohydrates in?

Answer 3

Carbonyl group

Question 4

Describe monosaccharides and provide examples.

Answer 4

-Single sugar molecules (e.g. glucose, galactose and fructose)

Question 5

Describe disaccharides. and provide examples.

Answer 5

Two sugar molecules (e.g. glucose + fructose = sucrose)

Question 6

Describe Polysaccharides and provide examples.

Answer 6

many sugar molecules (e.g. starch in plant cells and glycogen in animal cells)

Question 7

Where are carbohydrates stored?

Answer 7

-Blood glucose -Liver glycogen -Muscle glycogen

Question 8

What is the catalyst for the breakdown of glycogen?

Answer 8

Glycogen phosphorylase

Question 9

What are the three stages that need to occur for energy to be extracted from CHO?

Answer 9

-Glycolysis -TCA cycle (krebs) -Oxidative phosphorylation

Question 10

What is glycolysis?

Answer 10

The oxidation of glucose or glycogen.

Question 11

Where does glycolysis take place?

Answer 11

Cytoplasm

Question 12

What is produced during aerobic glycolysis vs anaerobic glycolysis?

Answer 12

Pyruvate Lactate

Question 13

What does glycolysis require?

Answer 13

glucose, enzymes, co-enzymes and ADP

Question 14

What does glycolysis produce?

Answer 14

Pyruvate, NADH and ATP

Question 15

What occurs in steps 1-3 in glycolysis and what is the primary regulator of speed?

Answer 15

Energy investment to be recouped later. Atp is required and some ADP is produced Phosphofruktokinase

Question 16

What occurs in steps 4-5 in glycolysis?

Answer 16

Cleavage of six-carbon sugar to two three-carbon sugars

Question 17

What occurs in steps 6-10 in glycolysis?

Answer 17

Energy generation

Question 18

What occurs in step 7 in glycolysis?

Answer 18

First stage where ATP is generated

Question 19

In stage 6 of glycolysis what happens if the metabolic rate is very high?

Answer 19

NAD+ can become saturated with h+, so there is not enough free NAD+ available, this can cause a ‘bottleneck’ at step 6.

Question 20

What is produced in step 9 of glycolysis?

Answer 20

Some metabolic water.

Question 21

What occurs in step 10 of glycolysis?

Answer 21

Second and final ATP generating step. Pyruvate kinase is the catalyst

Question 22

How much ATP are produced when glucose is used vs glycogen

Answer 22

Glucose- 2 ATP Glycogen- 3ATP

Question 23

What are the rate limiting steps of glycolysis?

Answer 23

PFK activity drops when acidity increases, causes step 3 to be bottle necked. In step 6 NAD availability can be come limited

Question 24

Describe in a nut shell what glycolysis is

Answer 24

One glucose molecule is converted via 10 steps to form pyruvate. The energy yield is 2 ATPs

Question 25

In step one what does hexokinase do?

Answer 25

Helps trap the glucose molecule into the cell by enabling us the attach a phosphate group to it.

Question 26

In step three what does phosphofruktokinase (PFK) do?

Answer 26

Very sensitive to acidity therefore acidity can become rate limiting.

Question 27

In step three what does pyruvate kinase do?

Answer 27

Catalyses the formation of pyruvate

Question 28

What are the ATP generating steps?

Answer 28

7 and 10

Question 29

What are the three stages when extraction if energy from CHO occurs?

Answer 29

Glycolysis TCA cycle (kerbs) Oxidative phosphorylation

Question 30

Why do we produce lactate?

Answer 30

The rate of gylcolysis is faster than the subsequent stages of CHO metabolism (TCA and ETC) When metabolic rate is high, NADH availability is low and NAD availability is low.

Question 31

When do we produce pyruvate?

Answer 31

When metabolic rate is low and O2 availability is high, NAD availability is high

Question 32

What is pyruvate converted into in the mitochondria?

Answer 32

Acetyl-coenzymeA

Question 33

Where does glycolysis occur?

Answer 33

Cytosol

Question 34

Where does the TCA cycle and oxidative phosphorylation occur?

Answer 34

Mitochondria

Question 35

What does substrate level phosphorylation include?

Answer 35

ATP generated from PCr hydrolysis and glycolysis

Question 36

Does substrate level phosphorylation require oxygen?

Answer 36

No

Question 37

What determines the NAD availability?

Answer 37

Metabolic rate

Question 38

What happens when we have low NAD availability?

Answer 38

Favours lactate production

Question 39

What happens when we have high NAD availability?

Answer 39

Favours conversion of pyruvate to acetyl-coenzymeA

Question 40

What does TCA cycle start of with?

Answer 40

acetyl-coenzymeA

Question 41

Describe the TCA cycle?

Answer 41

A cyclical process of 8 steps

Question 42

What is the main purpose of the TCA cycle

Answer 42

Oxidise acetyl groups and strip off their electrons of the ETC

Question 43

What is the end product of one turn of the TCA cycle?

Answer 43

Oxaloacetate

Question 44

What is the net energy produced in the TCA cycle?

Answer 44

3 NADH 1 FADH2 1 GTP

Question 45

What occurs in step 1 of the TCA cycle?

Answer 45

Oxaloacetate reacts with acetyl CoA to form 6-carbon molecule citrate

Question 46

What occurs in step 3 and 4 of the TCA cycle?

Answer 46

Produces CO2 and NADH

Question 47

What occurs in step 5 of the TCA cycle?

Answer 47

Produces one GTP

Question 48

What occurs in step 6 of the TCA cycle?

Answer 48

Produces one FADH2

Question 49

What occurs in step 8 of the TCA cycle?

Answer 49

Produces one NADH and oxaloacetate

Question 50

How is NAD and FAD regenerated?

Answer 50

ETC

Question 51

What is the net energy yield from one glucose molecule?

Answer 51

36 ATP

Question 52

What is the net energy yield from one glycogen molecule?

Answer 52

37 ATP

Question 53

In the TCA cycle what is a substrate in step 1 and a product in step 8?

Answer 53

Oxaloacetate

Question 54

What is the capacity of PCr?

Answer 54

Low

Question 55

How fast can PCr produce energy?

Answer 55

In seconds

Question 56

What is the capacity of glycolysis?

Answer 56

Intermediate

Question 57

What is the capacity of oxidative phosphorylation?

Answer 57

High

Question 58

How fast can glycolysis produce energy?

Answer 58

Intermediate

Question 59

How fast can oxidative phosphorylation produce energy?

Answer 59

Low rate, mate rate can be achieved in 1-3 mins.

Question 60

What are the three metabolic pathways?

Answer 60

PCr Glycolysis Oxidative phosphorylation

Question 61

Do ATP levels within the muscles vary much?

Answer 61

No, even during intense exercise

Question 62

What does the PCr shuttle allow?

Answer 62

The transfer of phosphate bond energy within the cell

Question 63

Label the mitochondria

Answer 63

1. Inter membrane space 2. Matrix 3. Inner membrane