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Biology > Chapter 7: Cellular Respiration > Flashcards

Chapter 7: Cellular Respiration Flashcards

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1
Q

redox reaction

A

a pair of oxidation-reduction reactions that transfer an electron from one compound to another

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2
Q

oxidation

A

removal of an electron from a molecule

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3
Q

reduction

A

addition of an electron to a molecule

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4
Q

NAD

A

derivative of vitamin B3 and serves as an electron carrier

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5
Q

vitamin B3

A

niacin

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6
Q

NAD+

A

oxidised form of NAD

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7
Q

NADH

A

reduced form of NAD

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8
Q

What does an “H” indicate about a carrier molecule?

A

It is generally reduced

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9
Q

FAD

A

derivative of vitamin B2 and serves as an electron carrier

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10
Q

vitamin B2

A

riboflavin

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11
Q

FAD+

A

oxidised form of FAD

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12
Q

FADH2

A

reduced form of FAD

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13
Q

NADP

A

variation of NAD

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14
Q

What is adenosine monophosphate composed of?

A

An adenine, ribose and phosphate group

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15
Q

Why is energy required to bond phosphate groups to AMP and ADP?

A

Phosphate groups have a negative charge and repel each other, so more energy is needed to bond with each other

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16
Q

dephosphorylation

A

the release of one or two phosphate groups from ATP

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17
Q

Where does the energy needed to regenerate ATP come from?

A

The metabolism of glucose, fructose or galactose

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18
Q

phosphorylation

A

addition of an electron to a compound

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19
Q

substrate-level phosphorylation

A

the direct transfer of a phosphate group from an intermediate reaction to form ATP from ADP

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20
Q

Which two mechanisms can ATP be produced during the breakdown of glucose?

A

Substrate-level phosphorylation and oxidative phosphorylation

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21
Q

Which mechanism yields most of the ATP produced during the breakdown of glucose?

A

Oxidative phosphorylation

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22
Q

glycolysis

A

process of breaking glucose down to release energy

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23
Q

anaerobic

A

not requiring oxygen

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24
Q

Where does glycolysis take place?

A

In the cytoplasm of cells

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25
Q

What are the two ways glucose can enter the cell?

A

Through secondary transport against its gradient or through facilitated transport by integral proteins

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26
Q

GLUT protein

A

transport proteins that aide in facilitated transport of glucose

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27
Q

pyruvate

A

three-carbon sugar that results from glycolysis

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28
Q

What does glycolysis begin and end with?

A

It starts with a molecule of glucose and ends with two molecules of pyruvate

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29
Q

How many phases of glycolysis are there?

A

Ten

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30
Q

What happens in the first step of glycolysis?

A

Glucose is phosphorylated into glucose-6-phosphate

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31
Q

What enzyme converts glucose into glucose-6-phosphate?

A

Hexokinase

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32
Q

Where does hexokinase obtain the energy to phosphorylate glucose into glucose-6-phosphate?

A

ATP

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33
Q

What effect does the attached phosphate group have on glucose-6-phosphate?

A

It cannot interact with GLUT proteins due to its negative charge and cannot leave the cell anymore

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34
Q

What happens in the second step of glycolysis?

A

Glucose-6-phosphate is converted into fructose-6-phosphate

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35
Q

Which enzyme converts glucose-6-phosphate into fructose-6-phosphate?

A

Isomerase

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36
Q

isomerase

A

enzyme that catalyses the conversion of a molecule into one of its isomers

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37
Q

hexokinase

A

enzyme that catalyses the phosphorylation of six-carbon sugars

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38
Q

What happens in the third step of glycolysis?

A

Fructose-6-phosphate is phosphorylated into fructose-1,6-biphosphate

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39
Q

Which enzyme phosphorylates fructose-6-phosphate into fructose-1,6-biphosphate?

A

Phosphofructokinase

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40
Q

What type of enzyme is phosphofructokinase and what does this mean?

A

It is a rate-limiting enzyme so it is very active during high ADP amounts and not very active during low ADP amounts

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41
Q

What happens in the fourth step of glycolysis?

A

Fructose-1,6-biphosphate is split into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate

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42
Q

Which enzyme splits fructose-1,6-biphosphate?

A

Aldolase

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43
Q

What happens in the fifth step of glycolysis?

A

Dihydroxyacetone-phosphate is transformed into glyceraldehyde-3-phosphate

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44
Q

Which enzyme transforms dihydroxyacetone-phosphate into glyceraldehyde-3-phosphate?

A

Isomerase

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45
Q

How much ATP is used in the first half of glycolysis?

A

Two ATP molecules

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46
Q

What happens in step six of glycolysis?

A

Glyceraldehyde-3-phosphate is oxidised and then phosphorylated into 1,3-bisphosphoglycerate

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47
Q

Where do the oxidised electrons from glyceraldehyde-3-phosphate go?

A

They are picked up by NAD+

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48
Q

How much NADH is yielded from step six in glycolysis?

A

Two NADH molecules

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49
Q

Does the phosphorylation in step six in glycolysis require ATP?

A

No

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50
Q

What is the limiting factor in step six of glycolysis?

A

The amount of NAD+ available

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51
Q

What happens if there is not enough NAD+ in step six of glycolysis?

A

Glycolysis will slow down or stop

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52
Q

How can NADH be oxidised when it is short in supply?

A

It will oxidise readily in the presence of oxygen or fermentation can oxidise NADH without oxygen

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53
Q

What happens in step seven of glycolysis?

A

1,3-bisphosphoglycerate donates a phosphate group to ADP and 3-phosphoglycerate it formed

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54
Q

How much ATP is yielded in step seven of glycolysis?

A

Two ATP molecules

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55
Q

What type of phosphorylation happens in step seven of glycolysis?

A

Substrate-level glycolysis

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56
Q

What happens to the carbonyl group on 1,3-bisphosphoglycerate in step seven?

A

It is oxidised to a carboxyl group

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57
Q

Which enzyme transforms 1,3-bisphosphoglycerate into 3-phosphoglycerate?

A

Phosphoglycerate kinase

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58
Q

What happens in step eight of glycolysis?

A

The phosphate group in 3-phosphoglycerate moves to the second carbon to become 2-phosphoglycerate

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59
Q

Which enzyme transforms 3-phosphoglycerate into 2-phosphoglycerate?

A

Phosphoglycerate mutase

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60
Q

mutase

A

a type of isomerase that moves a functional group within the same molecule

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61
Q

kinase

A

transfers a phosphate group from ATP to another molecule

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62
Q

What enzyme oxidises glyceraldehyde-3-phosphate?

A

Dehydrogenase

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63
Q

dehydrogenase

A

removes hydrogen atoms from a molecule

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64
Q

What happens in step nine of glycolysis?

A

2-phosphoglycerate loses water to become phosphoenolpyruvate

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65
Q

Which enzyme dehydrates 2-phosphoglycerate?

A

Enolase

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66
Q

What happens in the tenth step of glycolysis?

A

Phosphoenolpyruvate is dephosphorylated and is transformed into pyruvate

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67
Q

How much ATP is yielded from step ten of glycolysis?

A

Two ATP molecules

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68
Q

Which enzyme converts phosphoenolpyruvate into pyruvate?

A

Pyruvate kinase

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69
Q

What is the difference between pyruvate and pyruvic acid?

A

Pyruvic acid is an acid and pyruvate is in salt form

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70
Q

Why are many enzymes named after their reverse reactions?

A

Those enzymes can catalyse both forward and reverse reactions

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71
Q

What is produced from glycolysis?

A

Two pyruvate, four ATP and two NADH

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72
Q

What is the net gain of ATP and NADH?

A

Two ATP and two NADH

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73
Q

aerobic respiration

A

when organisms convert energy in the presence of oxygen

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74
Q

What type of enzyme is pyruvate kinase?

A

It is a rate-limiting enzyme for glycolysis

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75
Q

coenzyme A

A

derivative of vitamin B5 and is a carrier compound

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76
Q

vitamin B5

A

pantothenic acid

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77
Q

Where does pyruvate go after glycolysis?

A

It travels to the mitochondrial matrix

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78
Q

pyruvate dehydrogenase complex

A

a complex of three enzymes that converts pyruvate into acetyl-CoA

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79
Q

What must happen to pyruvate before it enters the citric acid cycle?

A

It must be converted into acetyl-CoA

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80
Q

What happens in the first step of the oxidation of pyruvate?

A

A carboxyl group is removed from pyruvate to produce a hydroxyethyl group

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81
Q

Which enzyme decarboxylates pyruvate?

A

Pyruvate dehydrogenase

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82
Q

What happens to the carboxyl group removed from pyruvate?

A

It is released as carbon dioxide

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83
Q

What happens in step two of the oxidation of pyruvate?

A

The hydroxyethyl group is oxidised

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84
Q

What happens to the oxidised electrons from the hydroxyethyl group?

A

They are picked up by NAD+ to form NADH

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85
Q

What is coenzyme A bound to?

A

It is bound to a sulfhydryl group

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86
Q

What happens when a hydroxylethyl group is oxidised?

A

It becomes an acetyl group

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87
Q

What is the chemical formula for an acetyl group?

A

CH3CO

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88
Q

What happens in step three of the oxidation of pyruvate?

A

The acetyl group is transferred to CoA to produce acetyl-CoA

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89
Q

citric acid cycle

A

series of enzyme-catalysed reactions to extract energy from carbohydrates

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90
Q

What are other names for the citric acid cycle?

A

The TCA cycle and the Krebs cycle

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91
Q

What is the origin for the name TCA cycle?

A

The first two intermediates of the cycle are tricarboxylic acids

92
Q

tricarboxylic acid

A

acid with three carboxyl groups

93
Q

Where does the citric acid cycle happen?

A

In the mitochondrial matrix

94
Q

oxaloacetate

A

four-carbon molecule

95
Q

citrate

A

six-carbon molecule that has three carboxyl groups

96
Q

What happens in step one of the citric acid cycle?

A

An acetyl group and oxaloacetate combine to create citrate

97
Q

Why is step one of the citric acid cycle irreversible?

A

It is highly exergonic

98
Q

What happens to CoA after the acetyl group bonds with oxaloacetate?

A

It diffuses away to bond with another acetyl group

99
Q

condensation

A

chemical reaction when two small molecules form a larger one but with the removal of a functional group or molecule

100
Q

What type of reaction is citrate synthesis?

A

Condensation reaction

101
Q

How is the rate of citrate synthesis controlled?

A

By negative feedback and the amount of ATP available

102
Q

How does the amount of ATP affect citrate synthesis?

A

The more ATP available, the slower the reaction

103
Q

negative feedback

A

when a process feeds back into itself and slows the process down

104
Q

What happens in step two of the citric acid cycle?

A

Citrate is converted into isocitrate

105
Q

How is citrate converted into isocitrate?

A

It loses a molecule of water, then gains another

106
Q

isocitrate

A

isomer of citrate

107
Q

What happens in step three of the citric acid cycle?

A

Isocitrate is oxidised into alpha-ketoglutarate

108
Q

What is produced in step three of the citric acid cycle?

A

Carbon dioxide

109
Q

What happens to the oxidised electrons from isocitrate?

A

NAD+ is reduced to NADH

110
Q

How is alpha-ketoglutarate production regulated?

A

By the negative feedback from ATP

111
Q

What happens in step four of the citric acid cycle?

A

Alpha-ketoglutarate is oxidised into a succinyl group that to CoA to form succinyl-CoA

112
Q

How is succinyl-CoA production regulated?

A

Feedback inhibition of ATP, succinyl-CoA and NADH

113
Q

What enzyme catalyses citrate production?

A

Citrate synthase

114
Q

What enzyme catalyses isocitrate production?

A

Aconitase

115
Q

What enzyme catalyses alpha-ketoglutarate production?

A

Isocitrate dehydrogenase

116
Q

What enzyme catalyses succinyl-CoA production?

A

Alpha-ketoglutarate dehydrogenase

117
Q

What is produced in step four of the citric acid cycle?

A

Carbon dioxide

118
Q

What type of reactions occur in steps three and four of the citric acid cycle?

A

Oxidation and decarboxylation reactions

119
Q

What happens to the oxidised electrons from alpha-ketoglutarate?

A

NAD+ is reduced to NADH

120
Q

What happens in step five of the citric acid cycle?

A

Succinyl-CoA is converted to succinate

121
Q

How is succinyl-CoA converted to succinate?

A

A phosphate group substitutes CoA in succinyl-CoA which is then phosphorylated to succinate

122
Q

What type of phosphorylation occurs in step five of the citric acid cycle?

A

Substrate-level phosphorylation

123
Q

Where does the phosphorylated phosphate group from succinyl-CoA go?

A

It joins to create either ATP or GTP

124
Q

Guanosine triphosphate

A

Energy equivalent to ATP but it has the base guanine instead of adenine

125
Q

What enzyme catalyses succinate production?

A

Succinyl-CoA synthetase

126
Q

synthetase

A

enzyme that catalyses a synthesis reaction by using energy from ATP or GTP

127
Q

What is the difference between synthetase and synthase?

A

Synthetase uses energy from ATP or GTP and synthase does not

128
Q

How many forms of succinyl-CoA synthetase are there and how do they differ?

A

There are two forms, one which specialises in ATP production and another in GTP

129
Q

isozyme

A

different forms of enzymes with the same formula but different structures

130
Q

What happens in step six of the citric acid cycle?

A

Succinate is converted to fumarate

131
Q

How is succinate converted to fumarate?

A

Two hydrogen atoms are stripped from succinate

132
Q

Where do the stripped hydrogen atoms from succinate go?

A

They are picked up by FAD to reduce it to FADH2

133
Q

Why is FAD used in step six of the citric acid cycle instead of NAD+?

A

The electrons in the hydrogen atom are not energetic enough so they can only reduce FAD

134
Q

How do FAD and NAD+ differ when transferring electrons?

A

FAD transports electrons directly to the electron transport chain

135
Q

Which enzyme catalyses fumarate production?

A

Succinate dehydrogenase

136
Q

What happens in step seven of the citric acid cycle?

A

Fumarate is converted to malate

137
Q

How is fumarate converted to malate?

A

Water is added to fumarate

138
Q

Which enzyme catalyses malate production?

A

Fumarase

139
Q

What happens in step eight of the citric acid cycle?

A

Malate is converted to oxaloacetate

140
Q

How is malate converted to oxaloacetate?

A

Malate is oxidised to oxaloacetate

141
Q

What happens to the oxidised hydrogen atom from malate?

A

It reduces NAD+ to NADH

142
Q

amphibolic

A

both catabolic and anabolic

143
Q

What are the overall products of the citric acid cycle?

A

Two CO2, three NADH, one FADH2 and one ATP or GTP molecule

144
Q

electron transport chain

A

series of four protein complexes along with electron carriers that pumps protons across the inner mitochondrial membrane

145
Q

prosthetic group

A

tightly-bound nonprotein molecule that is required for protein activity

146
Q

What is the difference between a prosthetic group and a cofactor?

A

A cofactor is any nonprotein substance required for protein activity, whereas a prosthetic group has the same role but is tightly bound to the protein

147
Q

What are the main components of complex I?

A

An iron-sulphur containing protein, FMN and NADH dehydrogenase

148
Q

What is the prosthetic group in complex I?

A

Flavin mononucleotide

149
Q

flavin mononucleotide

A

prosthetic group in complex I that is derived from vitamin B2

150
Q

How many amino acid chains is NADH dehydrogenase made up of?

A

Forty-five

151
Q

How many H+ can complex I pump?

A

Four H+

152
Q

Where does complex I receive its electrons from?

A

NADH

153
Q

What is another name for complex II?

A

Succinate dehydrogenase

154
Q

What are the main components of complex II?

A

Four succinate dehydrogenase subunits and ubiquinone B

155
Q

ubiquinone

A

lipid soluble coenzyme that is part of the electron transport chain

156
Q

How is ubiquinone represented?

A

Q

157
Q

What is ubiquinone’s reduced form?

A

QH2

158
Q

What does ubiquinone do?

A

It receives electrons from complexes I and II and delivers them to complex III

159
Q

Where does complex II receive its electrons from?

A

FADH2

160
Q

Why is less ATP produced from NADH2?

A

Electrons carried by NADH2 bypass the first complex and do not energise the first pump, so less protons are pumped

161
Q

What factor determines the amount of ATP produced in the electron transport chain?

A

The number of protons pumped

162
Q

What is complex III composed of?

A

A Rieske protein, and cytochrome b and c proteins

163
Q

What makes up the centre of a Rieske protein?

A

A 2Fe-2S centre

164
Q

What is another name for complex III?

A

Cytochrome oxidoreductase

165
Q

heme group

A

molecule with an iron ion at its core

166
Q

What prosthetic group does cytochrome have?

A

A prosthetic group of heme

167
Q

What role does heme play in cytochrome in complex III?

A

It carries electrons from complex III to complex IV

168
Q

What are the oxidation states of Fe in cytochrome?

A

Fe++ and Fe+++

169
Q

What is complex IV composed of?

A

Cytochrome c, a and a3

170
Q

How many heme groups does complex IV have?

A

Two heme groups, one in cytochrome a and one in cytochrome a3

171
Q

How many copper centres does complex IV have?

A

It has a binuclear CuA centre and a CuB centre

172
Q

Where are electrons in complex IV transported to?

A

They are used to reduce oxygen

173
Q

What happens to the reduced oxygen in complex IV?

A

It picks up two hydrogen ions from its surroundings to create water

174
Q

chemiosmosis

A

the movement of ions across the membrane with their electrochemical gradient

175
Q

What happens to all the pumped H+ from the electron transport chain?

A

It travels through ATP synthase by chemiosmosis to form ATP from ADP

176
Q

ATP synthase

A

enzyme that facilitates the addition of a phosphate group to ADP

177
Q

What percentage of ATP is produced due to chemiosmosis?

A

Ninety percent

178
Q

oxidative phosphorylation

A

production of ATP through chemiosmosis in the presence of oxygen

179
Q

fermentation

A

regenerates NAD+ from NADH when there is no oxygen to serve as the final electron acceptor

180
Q

anaerobic respiration

A

when organisms convert energy in the absence of oxygen

181
Q

methanogen

A

archaeans that reduce carbon dioxide to methane to oxidise NADH

182
Q

sulphate-reducing bacteria

A

bacteria that reduce sulphate to hydrogen sulphide to oxidise NADH

183
Q

What are the two main types of fermentation?

A

Lactic acid and alcohol fermentation

184
Q

Which fermentation method is used by animals?

A

Lactic acid fermentation

185
Q

Which types of cells in the body use lactic acid fermentation often?

A

Red blood cells and skeletal muscle cells

186
Q

Why must red blood cells use lactic acid fermentation?

A

They do not have mitochondria and cannot carry out aerobic respiration

187
Q

What happens to lactic acid that has built up in the muscles?

A

It is removed by the bloodstream, loses a hydrogen to become lactate and is metabolised in the liver

188
Q

What is the chemical equation for lactic acid fermentation?

A

Pyruvic acid + NADH lactic acid + NAD+

189
Q

Which enzyme catalyses lactic acid fermentation?

A

Lactate dehydrogenase

190
Q

What happens to lactate in the liver?

A

It can be reconverted to pyruvic acid for further catabolisation

191
Q

What is the chemical equation for alcohol fermentation?

A

Pyruvic acid + H+ -> CO2 + acetaldehyde + NADH + H+ -> ethanol + NAD+

192
Q

What happens in the first chemical reaction of alcohol fermentation?

A

Pyruvic acid is decarboxylated to produce acetaldehyde

193
Q

Which enzyme and coenzyme are involved in the first chemical reaction of alcohol fermentation?

A

Pyruvate decarboxylase and thiamine pyrophosphate

194
Q

thiamine pyrophosphate

A

derived from vitamin B1

195
Q

vitamin B1

A

thiamine

196
Q

What happens in the second chemical reaction of alcohol fermentation?

A

Acetaldehyde is reduced to ethanol and NADH is oxidised to NAD+

197
Q

Where does the ethanol in alcoholic beverages come from?

A

Yeast in beverages ferments pyruvic acid into ethanol

198
Q

obligate anaerobes

A

organisms that live and grow in the absence of oxygen

199
Q

glycogen

A

stores energy in animals

200
Q

What happens to glucose when there is adequate ATP available?

A

It is stored as glycogen

201
Q

Where is glycogen stored in the body?

A

In the liver and muscle cells

202
Q

How does glucose stored in glycogen enter the glycolytic pathway?

A

Glycogen is broken down into glucose-1-phosphate and converted to glucose-6-phosphate to enter the glycolytic pathway

203
Q

Can fructose and galactose be catabolised the same way glucose can?

A

Yes

204
Q

How effective is fructose and galactose catabolism compared to glucose catabolism?

A

Fructose and galactose produce the same amount of ATP as glucose does

205
Q

How do proteins find their way into glucose metabolism?

A

Excess amino acids from hydrolysed proteins can replace intermediates and reactants in glucose metabolism

206
Q

What must happen to an amino acid before it enters the glycolytic pathway?

A

It must have its amino group removed

207
Q

What happens to an amino acid’s removed amino group when it enters the glycolytic pathway?

A

It is converted to ammonia

208
Q

What happens to ammonia produced in the body?

A

The liver synthesises urea from ammonia and carbon dioxide which leaves the body in urine

209
Q

How do triglycerides enter the glycolytic pathway?

A

Glycerol can be converted to glycerol-3-phosphate to enter glycolysis, and fatty acids can be oxidised into acetyl groups

210
Q

How are fatty acids catabolised into acetyl groups?

A

Through beta oxidation

211
Q

beta oxidation

A

oxidation process where fatty acids are catabolised

212
Q

How can glucose entry to the cell be regulated?

A

With GLUT proteins

213
Q

How does GLUT4 control glucose entry to the cell?

A

When insulin binds to a receptor, it causes a GLUT4 containing vesicle to merge with the plasma membrane to allow glucose to enter

214
Q

What amino acid can pyruvate be converted to?

A

Alanine

215
Q

What is the main enzyme controlled in glycolysis?

A

Phosphofructokinase

216
Q

What factors affect phosphofructokinase’s activity?

A

High levels of ATP or citrate and more acidic pH all slow it down

217
Q

What does a high concentration of citrate indicate?

A

There is a possible blockage in the citric acid cycle

218
Q

What does increased acidity in aerobic respiration indicate?

A

Acids from fermentation are accumulating

219
Q

What factors affect pyruvate kinase’s activity?

A
  1. High levels of energy and alanine slow it down
  2. High levels of fructose-1,6-bisphosphate increase activity
  3. When the enzyme is phosphorylated, it becomes less active
220
Q

phosphatase

A

removes a phosphate group from a molecule

221
Q

What factors regulate pyruvate dehydrogenase?

A

High levels of acetyl groups or NADH lowers activity, and phosphorylating it slows it down

222
Q

Which enzymes are regulated in the citric acid cycle?

A

Isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase

223
Q

What factors regulate isocitrate dehydrogenase?

A

High levels of ATP and NADH slow the enzyme down

224
Q

What factors regulate alpha-ketoglutarate dehydrogenase?

A

High levels of ATP, NADH and succinyl CoA slow this enzyme down

225
Q

What can excess alpha-ketoglutarate in the citric acid cycle be used for?

A

It can be converted to glutamate

Biology (9 decks)

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