Glycolysis

Question 1

What is glycolysis?

Answer 1

The breakdown of glucose to smaller molecules, so producing ATP

Question 2

Where does glycolysis take place?

Answer 2

In the cytoplasm

Question 3

What is an aldehyde?

Answer 3

A compound containing a functional group with the structure R−CHO

Question 4

What is a ketone?

Answer 4

A compound containing a functional group with the structure R1−CO−R2

Question 5

What is a carboxylic acid?

Answer 5

An acid compound containing a functional group with the structure R−COOH

Question 6

What suffix is used to denote a sugar?

Answer 6

“-ose”

Question 7

Why is it important to be able to recognise sugars?

Answer 7

Sugars like glucose can often exist in different forms that are all in equilibrium

Question 8

What is a triose?

Answer 8

a sugar with 3 carbons

Question 9

What is a sugar with three carbons called?

Answer 9

a triose

Question 10

What is a hexose and give an example?

Answer 10

a sugar with 6 carbons,

eg glucose

Question 11

What is the structural difference between fructose and glucose?

Answer 11

While glucose tends to form a six-membered (pyranose) ring, fructose forms a 5- membered (furanose) ring

Question 12

How are proteins formed from amino acids?

Answer 12

the amino group of one amino acid joins to the carboxyl group of its neighbour (a peptide bond)

Question 13

What acids are common in metabolism?

Answer 13

Keto acids

Question 14

What is glucose converted to in glycolysis?

Answer 14

pyruvate

Question 15

What is the initial stage of glycolysis

Answer 15

Phosphorylation, which consumes ATP

Question 16

What does the first phosphorylation do to the glucose undergoing glycolysis?

Answer 16

Traps glucose in the cell, because glucose-6-P is ionized and unable to cross the cell membrane as it no longer matches any transport proteins

Question 17

What is the second step of glycolysis?

Answer 17

isomerization

Question 18

What occurs to the Glucose-6-P in the isomerization stage of glycolysis?

Answer 18

Glucose-6-P converted to fructose-6-P

Both sugars = C6H1206

Question 19

What is the third stage of glycolysis?

Answer 19

Another phosphorylation

Question 20

What occurs to the fructose-6-P in the second phosphorylation stage of glycolysis?

Answer 20

CONSUMES ATP

Forms a hexose diphosphate that can be split into two phosphorylated 3-carbon compounds

Question 21

What is the fourth stage of glycolysis?

Answer 21

Cleavage + isomerization

Question 22

What occurs to the hexose diphosphate in cleavage + isomerization of the fourth stage of glycolysis?

Answer 22

Forms two phosphorylated 3­ carbon compounds, then allows dihydroxyacetone-P (a triose) to be converted to glyceraldehyde-3-P which can be metabolized

Question 23

What is the fifth stage of glycolysis?

Answer 23

Oxidative phosphorylation

Question 24

What occurs to glyceraldehyde-3-P in oxidative phosphorylation in glycolysis?

Answer 24

Glyceraldehyde-3-P is simultaneously oxidized and phosphorylated

Hydrogen and electrons from glyceraldehyde-3-P are passed to nicotinamide adenine dinucleotide (NAD+)

Question 25

What is Nicotinamide adenine dinucleotide (NAD+/NADH + H+) made up of?

Answer 25

1 Nicotinamide molecule containing the reactive site 1 Adenine molecule 2 Ribose molecules sandwiching the Adenine

Question 26

What is the name for the adenine-ribose complex found in NAD+?

Answer 26

Adenosine

Question 27

What is the difference between NAD+ and NADP?

Answer 27

In NAD, R = H, while in the related nicotinamide adenine dinucleotide phosphate (NADP), R = phosphate

Question 28

What provides the nicotinamide part of the NAD+ molecule?

Answer 28

Vitamin B3 (niacin)

Question 29

How is vitamin B3 (niacin) made by the body?

Answer 29

It isn't, it has to be provided in the diet

Question 30

What does lack of Vitamin B3 (niacin) cause?

Answer 30

pellagra ­- Sensitivity to sunlight, dermatitis, alopecia, glossitis, weakness, ataxia

Question 31

What is the sixth stage of glycolysis?

Answer 31

The transfer of a phosphate to ADP and so the production of ATP

Question 32

What is the ratio of ATP produced/glucose molecules consumed in glycolysis in the first ATP producing stage?

Answer 32

2 ATP per molecule of glucose

Question 33

What is the seventh stage of glycolysis?

Answer 33

molecular rearrangement

Question 34

What occurs in the molecular rearrangement phase of glycolysis?

Answer 34

Phosphate group moved from one position to another (isomerization)

Question 35

What is the eighth stage of glycolysis?

Answer 35

Dehydration

Question 36

Why does dehydration occur in glycolysis?

Answer 36

It favours the transfer of phosphate to ADP

Question 37

What is the final stage of glycolysis?

Answer 37

The second transfer of phosphate to ADP and so ATP production occurs

Question 38

What is the ratio of ATP produced/glucose molecules consumed in glycolysis in the second ATP producing stage?

Answer 38

2 ATP per molecule of glucose

Question 39

How much ATP is produced per molecule of glucose consumed in glycolysis?

Answer 39

four

Question 40

What are the stages of glycolysis

Answer 40

``` 1st Phosphorylation Isomerization 2nd Phosphorylation Cleavage + isomerization Oxidative phosphorylation 1st Transfer of phosphate to ADP Molecular rearrangement Dehydration 2nd Transfer of phosphate to ADP ```

Question 41

Discuss glycolysis in aerobic conditions

Answer 41

Under aerobic conditions NAD+ is regenerated because NADH passes the electrons and the hydrogen atoms which it receives from glyceraldehyde-3-P through a system known as the electron transfer chain which combines them with molecular oxygen to form water -The electron transfer system also generates ATP

Question 42

Discuss glycolysis in anaerobic conditions

Answer 42

In the absence of molecular oxygen (anaerobic conditions) NADH builds up because NAD+ cannot be regenerated -If this situation persisted glycolysis would halt

Question 43

How is NAD+ regenerated?

Answer 43

In humans, NADH is re-oxidized by reducing | pyruvate to lactate

Question 44

What is a downside to the buildup of lactate as a result of regenerating NAD+?

Answer 44

It is this lactate that is responsible for muscle aches experienced after prolonged exercise!

Question 45

How does yeast regenerate NAD+?

Answer 45

To regenerate NAD+ it converts pyruvate to ethanol | Hence beer🍺

Question 46

What enzymes are key in how the rate of glycolysis is controlled?

Answer 46

1. Hexokinase 2. Phosphofructokinase 3. Pyruvate kinase

Question 47

What does hexokinase do?

Answer 47

Catalyses: glucose → glucose-6-P

Question 48

What does phosphofructokinase do?

Answer 48

Catalyses: fructose-6-P → fructose-1,6- | bisphosphate

Question 49

What does pyruvate kinase do?

Answer 49

Catalyses: phosphoenolpyruvate → pyruvate

Question 50

What enzyme is the most important point at which glycolysis is regulated?

Answer 50

phosphofructokinase

Question 51

How does phosphofructokinase regulate the rate of glycolysis?

Answer 51

1. High [ATP] allosterically inhibits the enzyme 2. Low pH inhibits the enzyme (lactate accumulation) 3. High [citric acid] inhibits 4. High [fructose-6-P] stimulates the enzyme

Question 52

Why is the regulation of the rate of glycolysis important?

Answer 52

so that glucose stores are only drawn on when energy is required and when conditions will allow sugars to be broken down

Question 53

What else may regulate the rate of glycolysis?

Answer 53

the concentration of certain hormones

Question 54

How many types of amino acids are there in the body?

Answer 54

20

Question 55

How many ketone bodies are keto acids?

Answer 55

2 Ketone bodies are keto acids, one is not

Question 56

What are keto acids useful for?

Answer 56

Transamination

Question 57

What enzyme converts glucose to glucose-6-P?

Answer 57

Hexokinase

Question 58

How much ATP is used vs created in glycolysis?

Answer 58

2ATP used 4ATP created Per glucose consumed

Question 59

What causes lactate acidosis?

Answer 59

The protons released by ATP -> ADP