Respiration, Sugar & Carbohydrates

Question 1

The whole process of breaking down glucose to ATP is called…?

Answer 1

Respiration.

Question 2

Where in the cell does glycolysis take place?

Answer 2

In the cytosol.

Question 3

Where in the cell does the TCA / Krebs cycle take place?

Answer 3

In the mitochondria.

Question 4

What is anaerobic respiration?

Answer 4

Anaerobic respiration is the fermentation of pyruvate into ethanol / lactate. This only happens in the absence of oxygen.

Question 5

Why is anaerobic respiration sub-optimal?

Answer 5

Only 4ATP is produced.

Question 6

What is the name for the oxidative breakdown of glucose to pyruvate?

Answer 6

Glycolysis.

Question 7

In glycolysis, how many molecules of pyruvate are formed from one molecule of glucose?

Answer 7

Two.

Question 8

Overall, in glycolysis, one molecule of glucose is oxidated to two molecules of pyruvate. How many molecules of ATP are used, how many molecules of ATP are formed and how many molecules of NADH are produced?

Answer 8

4ATP are produced, 2ATP are used and 2NADH are formed.

Question 9

What is the net gain of ATP in glycolysis?

Answer 9

+2ATP.

Question 10

Is oxygen necessary for glycolysis?

Answer 10

No.

Question 11

In anaerobic conditons ……………… can ferment. It is designed so that the ……………. is recycled and glycolysis can continue.

Answer 11

Pyruvate, NADH.

Question 12

In what cells can fermented pyruvate be used in the form of lactate for short-term energy?

Answer 12

Muscle cells.

Question 13

In aerobic conditions, pyruvate crosses two membranes to enter the …………………. ……………….. .

It is …………………. by pyruvate dehydrogenase complex to produce the cofactor ………………… ……………….. .

Answer 13

Mitochondrial matrix.

Decarboxylated, acetyl CoA.

Question 14

What is the cofactor produced by decarboxylation of pyruvate?

Answer 14

Acetyl CoA.

Question 15

In the krebs cycle, as carbon is removed, what is generated and where are electrons stored?

Answer 15

Carbon dioxide is generated and electrons are stored as NADH.

Question 16

How many carbons are used in each turn of the krebs cycle?

Answer 16

Two.

Question 17

Where in the cell does the electron transport chain take place?

Answer 17

In the inner mitochondrial membrane.

Question 18

NADH and FADH2 generated in the krebs cycle are passed into the electron transport chain. What happens to them there?

Answer 18

They are oxidised back to NAD and FAD.

Question 19

The electrons released when NADH and FADH2 are oxidised into NAD and FAD are passed through a series of ……………… …………….. and donated to …………….. to form water.

Answer 19

Electron carriers, water.

Question 20

What are the electron carriers in the electron transport chain grouped into?

Answer 20

Carrier complexes.

Question 21

Carrier complexes in the electron transport chain have what associated pumps? What do these pumps do?

Answer 21

Proton (H+) pumps, which pump protons out of the mitochondria, setting up a gradient across the inner membrane.

Question 22

Proton pumps associated with carrier complexes set up a gradient across which membrane?

Answer 22

The inner membrane.

Question 23

The process of protons being pumped out of the mitochondria in the electron transport chain setting up a gradient across the inner membrane is called oxidative…?

Answer 23

…phosphorylation.

Question 24

What is the energy produced by the gradient across the inner membrane set up by the proton pumps in the electron transport chain used for?

Answer 24

ATP synthesis.

Question 25

Do carrier complexes in the electron transport chain pump protons into or out of the mitochondria?

Answer 25

Out of the mitochondria.

Question 26

Glucose is broken down stepwise in respiration in order to lower the...?

Answer 26

Activation energy for each reaction.

Question 27

Which enzyme complex converts pyruvate to acetyl CoA?

Answer 27

The pyruvate dehydrogenase complex.

Question 28

The pyruvate dehydrogenase complex, which converts pyruvate to acetyl CoA, is made of how many individual enzymes?

Answer 28

Three. 1. Pyruvate dehydrogenase. 2. Dihydrolipoyl transacetylase. 3. Dihydrolipoyl dehydrogenase.

Question 29

Which stage of respiration takes place in the mitochondrial matrix?

Answer 29

The krebs / TCA cycle.

Question 30

When it enters the TCA cycle, what is acetyl CoA broken up into, releasing energy and high energy electrons?

Answer 30

Two molecules of carbon dioxide.

Question 31

When CoA is broken up into two molecules of carbon dioxide as it enters the TCA cycle, what is released?

Answer 31

Energy and high energy electrons.

Question 32

When a double bond is added and a hogh energy electron is removed from malate, what is formed?

Answer 32

Oxaloacetate.

Question 33

Malate is turned to oxaloacetate by...?

Answer 33

...adding a double bond and removing a high energy electron.

Question 34

One turn of the citric acid cycle produces how many NADH, FADH2, GTP and CO2?

Answer 34

3 NADH, 1 FADH2, 1GTP and 2 CO2.

Question 35

The high energy electrons generated in the TCA cycle are carried to the electron transport chain by which activated carrier molecules?

Answer 35

NADH and FADH2.

Question 36

As electrons travel along the electron transport chain, do they lose or gain energy?

Answer 36

As thye move along the electron transport chain electron lose energy used to drive the the carrier complexes.

Question 37

What happens to the energy lost by electrons as they travel along the electron transport chain?

Answer 37

The energy is used to drive the electron carrier complexes whch set up the steep proton gradient across the mitochondrial membrane.

Question 38

Does maintaining the proton gradient across the mitochondrial membrane require energy input?

Answer 38

Yes.

Question 39

At the end of the electron transport chain, what is produced from electrons from the carriers, H+ ions that are added automatically from solution and O2?

Answer 39

Water!

Question 40

The movement of electrons in the electron transport chain is coupled to the pumping of protons creating a steep proton gradient. If there are a lot of protons, then is the pH low or high?

Answer 40

The pH is lower the more protons there are (because of their positive charge).

Question 41

ATP synthase uses the energy stored in the electrochemical proton gradient to produce what?

Answer 41

ATP!

Question 42

What is the name used to describe the force that is the energy generated by the flow of protons?

Answer 42

Proton motive force.

Question 43

Where is the energy stored that ATP synthase uses to produce ATP?

Answer 43

In the electrochemical proton gradient.

Question 44

If ATP synthase rotates the 'other' way, what happens?

Answer 44

ATP is hydrolysed to producce energy, which increases the proton gradient and therefore driving ATP synthesis once more.

Question 45

Can the TCA cycle be controlled?

Answer 45

Yes, at several steps.

Question 46

What do the enzymes pyruvate dehydrogenase, isocitrate dehydrogenase and ketoglutarate dehydrogenase do in the TCA cycle?

Answer 46

They can control the TCA cycle.

Question 47

If we have plenty of high-energy electrons, what will the cell assume and what will the result be?

Answer 47

If there are plenty of high-energy electrons, the cell will assume that we are well-nourished and inhibit pyruvate breakdown.

Question 48

Why are pyruvate dehydrogenase, isocitrate dehydrogenase and ketoglutarate dehydrogenase important in the TCA cycle?

Answer 48

They are the enzymes involved in key steps for inhibiting the production of key compounds. The cycle can, in theory, be regulated at every step but it tends to be at these key steps.

Question 49

Can glycolysis be controlled?

Answer 49

Yes, glycolysis is carefully controlled.

Question 50

How many of the steps in glycolysis cannot be reversed?

Answer 50

Three.

Question 51

When one stage of glycolysis is halted, why does the whole process stop?

Answer 51

The product made at that stage starts to accumulate, so the cell stops the whole cycle to prevent overaccumulation.

Question 52

True or false? The enzymes that can control glycolysis can be bypassed by a second set of enzymes!

Answer 52

True!

Question 53

How many protons make one ATP?

Answer 53

Four protons make one ATP in total, three to make it and one to export the ATP to the cytosol.

Question 54

For every molecule of glucose, how many molecules of ATP are produced?

Answer 54

Thirty.

Question 55

What is gluconeogenesis?

Answer 55

Gluconeogenesis is the generation of glucose from non-carbohydrate sources.

Question 56

What can be used to produced glucose in gluconeogenesis?

Answer 56

Pyruvate, lactate, glycerol and some amino acids.

Question 57

Which are the cells in the body NEED glucose as an energy source?

Answer 57

Brain cells.

Question 58

Gluceoneogenesis is a key mechanism for recycling which substance?

Answer 58

Lactate.

Question 59

Can lactate be stored in muscle cells?

Answer 59

No.

Question 60

Where is lactate recycled in gluconeogenesis?

Answer 60

In the liver.

Question 61

How many units are monosaccharides? Give some examples.

Answer 61

One. Glucose, fructose, galactose.

Question 62

Which type of carbohydrates can be aldehydes or ketones?

Answer 62

Monosaccharides.

Question 63

Where is the double bond in an aldehyde monosaccharide?

Answer 63

At the end of the molecule.

Question 64

Where is the double bond in a ketone monosaccharide?

Answer 64

In the middle of the molecule.

Question 65

What is a disaccharide? Give some examples.

Answer 65

Two units (monosaccharides) joined together. Sucrose, lactose, maltose.

Question 66

Which monosaccharides make up lactose?

Answer 66

Galactose and glucose.

Question 67

Two glucose molecules joined by an α(1,4) bond make...?

Answer 67

Maltose.

Question 68

In plants, what happens at night to starch trhat has been synthesised during the day?

Answer 68

It is degraded into glucose and maltose and exported out of the chloroplast into the cytosol.

Question 69

Why is maltose important in photosynthesis?

Answer 69

It is a common product of starch breakdown.

Question 70

What is the similarities and differences between maltose and trehalose?

Answer 70

They are both made of two α-glucose units. Maltose has a 1-4 bond, trehalose has a 1,1 bond.

Question 71

What regulation allows cells to switch from glucose breakdown to glucose synthesis? How does this work?

Answer 71

Feedback regulation. Under- or over-accumulation of glucose influences whether the reaction goes forwards or backwards and which enzymes are activated or inhibited.

Question 72

What is glucose synthesis called?

Answer 72

Gluconeogenesis.

Question 73

What is glucose breakdown called?

Answer 73

Glycolysis.

Question 74

Where is plant cells is starch made?

Answer 74

In the chloroplasts.

Question 75

Plants make sugars via photosynthesis, which are stored in the short-term in .................. as ................ until it is needed at night.

Answer 75

Chloroplasts, starch.

Question 76

Where in plant cells is starch stored in the long term?

Answer 76

Amyloplasts.

Question 77

What is the special function of amyloplasts?

Answer 77

Long term starch storage.

Question 78

What are the specific organelles for starch storage in plant cells called?

Answer 78

Amyloplasts.

Question 79

Why are starch molecules made from glucose in the amyloplast and not in the cytosol?

Answer 79

Starch molecules are too big to cross the membrane so they have to be transported into the amyloplast as sugar, then built into starch molecules.

Question 80

What are the two polymers of glucose that make up starch called?

Answer 80

Amylose and amylopectin.

Question 81

What is the difference between amylose and amylopectin?

Answer 81

Amylose is a largely unbranched chain of glucose molecules. Amylopectin branches roughly every 20-24 glucose molecules.

Question 82

What does amylopectin lack, which mean that the sugars are reached into the bloodstream more quickly?

Answer 82

Fibre.

Question 83

Is amylose or amylopectin more readily digested?

Answer 83

Amylopectin because the more branches a chain has, the more end enzymes have to work on.

Question 84

What is inulin a polymer of?

Answer 84

Fructose.

Question 85

Can the body digest inulin?

Answer 85

No.

Question 86

What is glycogen a polymer of?

Answer 86

Glucose.

Question 87

True or false? Glycogen is only found in liver and muscle tissue.

Answer 87

False. Glycogen is found in ALL tissue, but primarily in liver and muscle tissue.

Question 88

What is the first enzyme in glycogen degradation?

Answer 88

Glycogen phosphorylase.

Question 89

Which of the polymers of starch does glycogen most resemble? Amylose or amylopectin?

Answer 89

Amylopectin. It is a highly branched chain of glucose polymers with branches every 12 glucoses or so.

Question 90

Why is the highly branched structure of glycogen suited to its function as a rapidly released source of energy?

Answer 90

The highly branched structure means that enzymes can work on lots of 'ends' to meet sudden energy demands.

Question 91

What is the protein at the centre of a glycogen molecule called? What does it do?

Answer 91

Glycogenin. Glycogenin is a glycolsyltransferease which initiates glycogen synthesis.

Question 92

Why is glycogen more branched than inulin?

Answer 92

Animals need more energy than plants!

Question 93

What are the two intermediate structures between linear glucose polymers and cellulose fibres?

Answer 93

Cellulose microfibrils and cellulose macrofibrils. Chains of linear glucose polymers cross link into cellulose microfibrils which then align into cellulose macrofibrils and hence cellulose fibres.

Question 94

True or false? Cellulose is made in situ - at the site in the plant where it is required.

Answer 94

True.

Question 95

Chitin is a polymer of ............ molecules, commonly found...?

Answer 95

Glucose. Commonly found in insect exoskeletons, crustaceans and fish scales.

Question 96

Which are the first and second most abundant organic polymers?

Answer 96

First - cellulose. Second - chitin.

Question 97

In general, what are the two main purposes of polysaccharides?

Answer 97

Storage of sugars and structure.

Question 98

Name some sources of industrially purified starch.

Answer 98

Maize, tapioca, arrowroot, wheat, tapioca, rice and potato.

Question 99

Name some uses of purified starches.

Answer 99

Thickeners, stabilisers, emulsifiers and binders.

Question 100

Name some industrial uses of purified starches.

Answer 100

Paper manufacture (size), glues, plasterboard, biofuel, compostable plastics.

Question 101

Describe the structure and cellulose.

Answer 101

Cellulose is a long, unbranched chain of glucose molecules with beta 1-4 glycosidic bonds. It is a major support in plant cell walls.

Question 102

Bacteria and fungi have cellulase enzymes to digest cellulose, but mammals do not have cellulase - how is cellulose broken down in mammals?

Answer 102

Mammals rely on a symbiotic relationship with microorganisms in their gut to process cellulose.

Question 103

Ruminants have microbiota in their gut that allow them to process cellulose, but there is an additional step first - what is this?

Answer 103

'Chewing the cud' - ruminants regurgitate food and rechew it to help with digestion.