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Introduction to Genetics & Biochemistry > Respiration, Sugar & Carbohydrates > Flashcards

Respiration, Sugar & Carbohydrates Flashcards

1
Q

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

A

Respiration.

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2
Q

Where in the cell does glycolysis take place?

A

In the cytosol.

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3
Q

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

A

In the mitochondria.

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4
Q

What is anaerobic respiration?

A

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

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5
Q

Why is anaerobic respiration sub-optimal?

A

Only 4ATP is produced.

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6
Q

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

A

Glycolysis.

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7
Q

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

A

Two.

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8
Q

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?

A

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

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9
Q

What is the net gain of ATP in glycolysis?

A

+2ATP.

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10
Q

Is oxygen necessary for glycolysis?

A

No.

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11
Q

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

A

Pyruvate, NADH.

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12
Q

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

A

Muscle cells.

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13
Q

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

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

A

Mitochondrial matrix.

Decarboxylated, acetyl CoA.

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14
Q

What is the cofactor produced by decarboxylation of pyruvate?

A

Acetyl CoA.

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15
Q

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

A

Carbon dioxide is generated and electrons are stored as NADH.

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16
Q

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

A

Two.

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17
Q

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

A

In the inner mitochondrial membrane.

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18
Q

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

A

They are oxidised back to NAD and FAD.

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19
Q

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.

A

Electron carriers, water.

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20
Q

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

A

Carrier complexes.

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21
Q

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

A

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

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22
Q

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

A

The inner membrane.

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23
Q

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…?

A

…phosphorylation.

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24
Q

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?

A

ATP synthesis.

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25
Q

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

A

Out of the mitochondria.

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26
Q

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

A

Activation energy for each reaction.

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27
Q

Which enzyme complex converts pyruvate to acetyl CoA?

A

The pyruvate dehydrogenase complex.

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28
Q

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

A

Three.

  1. Pyruvate dehydrogenase.
  2. Dihydrolipoyl transacetylase.
  3. Dihydrolipoyl dehydrogenase.
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29
Q

Which stage of respiration takes place in the mitochondrial matrix?

A

The krebs / TCA cycle.

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30
Q

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

A

Two molecules of carbon dioxide.

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31
Q

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

A

Energy and high energy electrons.

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32
Q

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

A

Oxaloacetate.

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33
Q

Malate is turned to oxaloacetate by…?

A

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

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34
Q

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

A

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

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35
Q

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

A

NADH and FADH2.

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36
Q

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

A

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

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37
Q

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

A

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

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38
Q

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

A

Yes.

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39
Q

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?

A

Water!

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40
Q

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?

A

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

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41
Q

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

A

ATP!

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42
Q

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

A

Proton motive force.

43
Q

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

A

In the electrochemical proton gradient.

44
Q

If ATP synthase rotates the ‘other’ way, what happens?

A

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

45
Q

Can the TCA cycle be controlled?

A

Yes, at several steps.

46
Q

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

A

They can control the TCA cycle.

47
Q

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

A

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

48
Q

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

A

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.

49
Q

Can glycolysis be controlled?

A

Yes, glycolysis is carefully controlled.

50
Q

How many of the steps in glycolysis cannot be reversed?

A

Three.

51
Q

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

A

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

52
Q

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

A

True!

53
Q

How many protons make one ATP?

A

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

54
Q

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

A

Thirty.

55
Q

What is gluconeogenesis?

A

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

56
Q

What can be used to produced glucose in gluconeogenesis?

A

Pyruvate, lactate, glycerol and some amino acids.

57
Q

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

A

Brain cells.

58
Q

Gluceoneogenesis is a key mechanism for recycling which substance?

A

Lactate.

59
Q

Can lactate be stored in muscle cells?

A

No.

60
Q

Where is lactate recycled in gluconeogenesis?

A

In the liver.

61
Q

How many units are monosaccharides? Give some examples.

A

One. Glucose, fructose, galactose.

62
Q

Which type of carbohydrates can be aldehydes or ketones?

A

Monosaccharides.

63
Q

Where is the double bond in an aldehyde monosaccharide?

A

At the end of the molecule.

64
Q

Where is the double bond in a ketone monosaccharide?

A

In the middle of the molecule.

65
Q

What is a disaccharide? Give some examples.

A

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

66
Q

Which monosaccharides make up lactose?

A

Galactose and glucose.

67
Q

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

A

Maltose.

68
Q

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

A

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

69
Q

Why is maltose important in photosynthesis?

A

It is a common product of starch breakdown.

70
Q

What is the similarities and differences between maltose and trehalose?

A

They are both made of two α-glucose units.

Maltose has a 1-4 bond, trehalose has a 1,1 bond.

71
Q

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

A

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

72
Q

What is glucose synthesis called?

A

Gluconeogenesis.

73
Q

What is glucose breakdown called?

A

Glycolysis.

74
Q

Where is plant cells is starch made?

A

In the chloroplasts.

75
Q

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

A

Chloroplasts, starch.

76
Q

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

A

Amyloplasts.

77
Q

What is the special function of amyloplasts?

A

Long term starch storage.

78
Q

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

A

Amyloplasts.

79
Q

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

A

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.

80
Q

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

A

Amylose and amylopectin.

81
Q

What is the difference between amylose and amylopectin?

A

Amylose is a largely unbranched chain of glucose molecules.

Amylopectin branches roughly every 20-24 glucose molecules.

82
Q

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

A

Fibre.

83
Q

Is amylose or amylopectin more readily digested?

A

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

84
Q

What is inulin a polymer of?

A

Fructose.

85
Q

Can the body digest inulin?

A

No.

86
Q

What is glycogen a polymer of?

A

Glucose.

87
Q

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

A

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

88
Q

What is the first enzyme in glycogen degradation?

A

Glycogen phosphorylase.

89
Q

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

A

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

90
Q

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

A

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

91
Q

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

A

Glycogenin.

Glycogenin is a glycolsyltransferease which initiates glycogen synthesis.

92
Q

Why is glycogen more branched than inulin?

A

Animals need more energy than plants!

93
Q

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

A

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.

94
Q

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

A

True.

95
Q

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

A

Glucose.

Commonly found in insect exoskeletons, crustaceans and fish scales.

96
Q

Which are the first and second most abundant organic polymers?

A

First - cellulose.

Second - chitin.

97
Q

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

A

Storage of sugars and structure.

98
Q

Name some sources of industrially purified starch.

A

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

99
Q

Name some uses of purified starches.

A

Thickeners, stabilisers, emulsifiers and binders.

100
Q

Name some industrial uses of purified starches.

A

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

101
Q

Describe the structure and cellulose.

A

Cellulose is a long, unbranched chain of glucose molecules with beta 1-4 glycosidic bonds.

It is a major support in plant cell walls.

102
Q

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

A

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

103
Q

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

A

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

Introduction to Genetics & Biochemistry (21 decks)

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