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2nd yr- IBMS- Respiration and metabolism > Glycolysis and the TCA > Flashcards

Glycolysis and the TCA Flashcards

1
Q

What is the main aim of metabolism?

A

converting an energy source into carbon dioxide and water

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2
Q

Name the 2 pathways that metabolism is split into?

A
  1. Anabolic

2. Catabolic

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3
Q

What is the anabolic pathway of metabolism?

A

These are pathways concerned with the synthesis of cellular components
They decrease entropy and are reductive in nature

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4
Q

What is the catabolic pathway of metabolism?

A

These pathways are concerned with the degradation of cellular components
They are energy liberating

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5
Q

Name the currency of energy

A

ATP

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6
Q

How is ATP suited to its job

A

As it is unstable energy and energy rich

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7
Q

Name the bond that makes ARP energy rich

A

The acid anhydride bond

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8
Q

Why are the acid anhydride bonds energy rich?

A
  1. Due to charge repulsion between the adjacent phosphate groups
    Each negative charge repels one another making the molecule less stable than it would be otherwise
    2 .Due to the resonance of phosphate ions
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9
Q

Define oxidation

A

The removal of electrons and protons

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10
Q

What type of reaction is oxidation

A

Exogenic

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11
Q

Name the ultimate electron acceptor

A

Oxygen

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12
Q

What does TCA stand for?

A

Tricarboxylic acid cycle

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13
Q

Name the most common fuel in mammals?

A

GLUCOSE

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14
Q

Why is glucose important?

A

It is the only fuel that the brain uses

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15
Q

Describe the structure of glucose

A

It tends to have a ring conformation

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16
Q

Briefly happens to glucose molecules in glycolysis?

A

Glucose is converted into pyruvate

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17
Q

How can pyruvate be further broken down?

A
  1. Complete oxidation

2. Fermentation

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18
Q

Does fermentation or complete oxidation produce the most free energy ?

A

complete oxidation

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19
Q

Name the 2 parts of glycolysis

A
  1. Investment phase (costs us ATP)

2. Return phase

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20
Q

Name the stages of the ATP consuming phase of glycolysis?

A
  1. Phosphorylation of glucose into G-6P
  2. Isomerisation of G-6P into fructose-6-phosphate
  3. Phosphorylation of fructose-6-phosphate into fructose 1,6-bisphosphate
  4. Break down of fructose 1,6-bisphosphate into GAP and DHAP
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21
Q

Go though the first step of glycolysis

A

Glucose enters the cell using a transport protein and is phosphorylated to give Glucose – 6 Phosphate (G-6P)

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22
Q

What does glucose need help to enter the cell?

A

It cannot diffuse through due to its negative charge

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23
Q

What does the phosphorylation of glucose require?

A

ATP

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24
Q

What is the phosphorylation of glucose catalysed by?

A

Hexokinase

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25
What does Hexokinase need to function?
Magnesium
26
Is Glucose – 6 Phosphate stable or unstable? why?
Unstable due to the addition of a negative charge (Phosphate group )
27
What does glucose have a preference to form?
A 6 carbon ring
28
What is isomerisation?
When the molecular component of a compound doesn't change but the structural arrangement does
29
What catalysis the Isomerisation of G-6P?
phosphoglucose isomerase
30
What is Glucose-6-phosphate isomerised into?
1. An aldehyde 2. Then a ketone 3. Finally Fructose-6-phosphate
31
Name the end product of the iomerisation of glucose-6-phosphate
Fructose-6-phosphate
32
What happens to fructose-6-phosphate once it has formed?
It is phosphorylated
33
What does the Phosphorylation of fructose-6-phosphate require?
ATP
34
What is fructose-6 -phosphate phosphorylated into?
fructose 1,6-bisphosphate
35
Name the enzyme involved in the Phosphorylation of fructose-6-phosphate
phosphofructokinase (PFK)
36
Name the rate determining step in glycolysis
The Phosphorylation of fructose-6-phosphate
37
Why is the Phosphorylation of fructose-6-phosphate the rate determining step of glycolysis?
As the reaction favours the products
38
What do we need do to fructose-6-phosphate and why?
Need to break it down to release energy
39
How is fructose-6-phosphate broken down?
By Aldolase
40
What does is fructose 1,6- biphophate broken down into?
``` 1. Glyceraldehyde 3-phosphate (GAP) 2. Dihydroxyacetone phosphate (DHAP) ```
41
Is GAP needed in glycolysis or DHAP (or both)
GAP (Glyceraldehyde 3-phosphate)
42
What do we need to do to DHAP to make glycolysis more effective?
Convert it into GAP so it can be used in glycolysis
43
Name the enzyme that converts DHAP into GAP
Triose phosphate | isomerase
44
Name all the enzyme involved in the ATP consuming stage of glycolysis
1. Hexokinase (phosphorylation of glucose into G6P) 2. Phosphoglucose isomerase (somerisation of G-6P) 3. Phosphofructokinase-1 (Phosphorylates fructose 6-phophate into fructose 1,6-bisphosphate) 4. Aldose (Breaks down fructose 1,6-bisphosphate) 5. Triose phosphate isomerase (isomerisation of GAP to DHAP)
45
In a nut shell summarise the ATP consuming phase of glycolysis
The break down of a single 6 carbon molecule to 2 three carbon molecules costing TWO ATPs
46
How many ATPs are used in the ATP consuming phase of glycolysis?
2 ATPs
47
What does the ATP generation stage of glycolysis begin with?
Begins with the phosphorylation of Glyceraldehyde -3-phosphate
48
Name the stages of the ATP generating phase of glycolysis
1. phosphorylation of Glyceraldehyde -3-phosphate 2. Removal of phosphate from (1,3-BPG) to form 3-phosphoglycerate 3. 3 phosphoglycerateis converted into 2 phophoglycerbte 4. 2- phosphoglycerate is converted into PEP 4. PEP loses its phosphate group to form pyruvate and ATP
49
What is Glyceraldehyde -3-phosphate phosphylated into?
1,3-bisphosphogltcerate | 1,3-BPG
50
What molecules are involved into the phosphorylation of GAP into 1,3- biphophogitcerate
NAD+ and Phosphate
51
Which enzyme is involved in the phosphorylation of Glyceraldehyde -3-phosphate ?
Glyceraldehyde 3-phosphate dehydrogenase
52
What does the Glyceraldehyde 3-phosphate dehydrogenase result in?
1,3-bisphosphogltcerate (1,3-BPG) NADH H+
53
Describe 1,3-bisphosphogltcerate | 1,3-BPG
It has a high phosphorylation transfer potential
54
What does the fact that 1,3 BPG having a high phosphorylation transfer potential allow?
Allows for phosphate transferal onto ADP in the next step
55
What happens to 1,3-bisphosphogltcerate | (1,3-BPG) after it has been formed?
When it is in close proximity to ADP it removes its phosphate group
56
What does the removal of phosphate from 1,3-bisphosphogltcerate (1,3-BPG) require?
ADP and H+
57
Which enzyme aids the removal of phosphate from 1,3-bisphosphogltcerate (1,3-BPG)?
Phosphoglycerate | kinase
58
What does the removal of phosphate from 1,3-bisphosphogltcerate (1,3-BPG) form?
3-phosphoglycerate | and ATP
59
What happens to the 3-phosphoglycerate once it has formed?
It is converted into 2-phosphoglycerate
60
Name the enzyme that aids the the conversion of 3-phosphoglycerate into 2- phosphoglycerate
Phosphoglycerate mutase
61
How can we obtain ATP from 3-phophoglycerate?
3-phophoglycerate is converted in 2-phophoglycerate with the aid of Phosphoglycerate mutase Then Enolase converts the 2-phophoglycerate into Phosphenolpyruvate (PEP). This reaction yields ADP PEP is of high energy and wants to remove its phosphate the removal of this phosphate forms pyruvate and ATP
62
Which enzyme aids the conversion of 2-phophoglycerate into Phosphenolpyruvate (PEP)?
Enolase
63
How does PEP help release an ATP?
PEP is of high energy and wants to remove its phosphate the removal of this phosphate forms pyruvate and ATP
64
How many ATPs does the ATP consuming phase of glycolysis use?
2
65
How many ATPs does the ATP generating phase produce?
4
66
What does the break down of glucose produce overall?
2 ATPs and 2 pyruvate
67
Is the redox equilibrium of glucose break down balanced?
NO | We used 1 NAD+ to convert GAP into 1,3BPG
68
What must be regenerated through the metabolism of pyruvate and whY?
NAD+ needs to be regenerated as the redox equilibrium of glucose break down isn't balanced
69
State the overall equation for glucose metabolism in glycolysis
Glucose + 2Pi + 2ADP + 2NAD+ -> 2pyruvate + 2ATP + NADH + 2H+ + 2H2O
70
What can pyruvate be broken down into?
1. Ethanol 2. Lactase 3. Acetyl CoA
71
Why does fermentation occur?
When there's a lack of Oxygen
72
When pyruvate is broken down in a fermentation reaction what happens
1. Pyruvate is converted into Acetaldehyde realising CO2 | 2. Acetaldehyde is converted into ethanol (NAD+ is produced)
73
Name some organisms that do fermentation
Yeast
74
What is released when pyruvate is produced into lactate?
NAD+ is produced
75
When does the conversion of pyruvate into lactate occur?
When theres a lack of oxygen and the body is in need of energy
76
After glycolysis what does the pyruvate need to enter?
The citric acid cycle
77
Name the only entry point into the Krebs cycle?
Acetyle CoA
78
Through which reaction is pyruvate converted into Acetyl CoA?
Through an oxidative decarboxylation
79
What is the conversion of pyruvate into acetyl CoA mediated by?
Pyruvate dehydrogenase (PDH)
80
What is pyruvate dehydrogenase?
It is a multi enzyme complex of pyruvate decarboxylase, dihydro transacetylase and dihydrolipoyl dehydrogenase
81
Name the enzymes involved in the multi enzyme complex that aids the formation of acetyl CoA
1. pyruvate decarboxylase, 2. dihydro transacetylase 3. dihydrolipoyl dehydrogenase
82
What is the benefit of having a multi enzyme complex?
All the enzymes are attaches so there is no release of intermediates making the reaction bette
83
Go through the reactions involved in the pyruvate dehydrogenase (PDH) reaction
1. Decarboxylation 2. Oxidation 3. Acetyl CoA is added
84
Where does the pyruvate dehydrogenase reaction occur?
In the matrix of the mitochondria
85
What is produces in the Pyruvate dehydrogenase reaction?
NAD+ is converted into NADH
86
Talk though the stages of the TCA cycle?
1, Acetyl CoA production 2. Acetyl- CoA oxidation in the citric acid cycle 3. Electron transfer and oxidative phosphorylation occurs in the electron transport chain
87
What is the main aim of the TCA cycle?
To harvest high energy electrons from carbon fuel
88
Talk though the stages of the TCA cycle?
1, Acetyl CoA production 2. Acetyl- CoA oxidation in the citric acid cycle 3. Electron transfer and oxidative phosphorylation occurs in the electron transport chain
89
What does the TCA cycle provide?
The substrate for electron transport chain | Precursors for building amino acids, nucleotides and components of blood
90
What do the intermediates in the TCA cycle provide?
They proves a regulatory barrier
91
Name the main stages of the citric acid cycle
1. Citrate synthase 2. break up of the carrier 3. Oxidative decarboxylation of isocitrate 4. Oxidative Decarboxylation (5C to 4C) 5. Oxidative Decarboxylation (5C to 4C) 6. Oxidation 7. Oxidation, hydration
92
What does hexokinase do?
Catalyses the phosphorylation of glucose into Glucose – 6 Phosphate
93
What does phosphoglucose isomerase do?
Aids the isomerisation of G-6P
94
What does phosphofructokinase (PFK) do?
Phosphorylates fructose 6-phophate into fructose 1,6-bisphosphate
95
What is significant about the Phosphorylation of fructose-6-phosphate ?
It is the rate determine step of glycolysis
96
What does aldose do?
``` Breaks down fructose 1,6-bisphosphate into: 1. Glyceraldehyde 3-phosphate (GAP) 2. Dihydroxyacetone phosphate (DHAP) ```
97
What does Triose phosphate | isomerase do?
Aids in the conversion of DHAP into GAP
98
What does Phosphoglycerate | kinase do?
Phosphorylates GAP into 1,3 - BPG
99
What does Phosphoglycerate | kinase do?
Aids the removal of phosphate from 1,3-bisphosphogltcerate | 1,3-BPG
100
What does Phosphoglycerate mutase do?
Aids in the concversion of 3-phophoglycerate into 2-phophoglycerate
101
What does enolase do?
Converts 2-phophoglycerate into Phosphenolpyruvate | (PEP)?
102
What is the condensation of acetyl CoA and oxaloacetate catalysed by?
citrate synthase
103
What does the equilibrium in the aldol condensation reaction favour?
citrate synthase
104
What does acetyl CoA react with when it enters the mitochondria?
Reacts with Oxaloacetate | to form citrate and citryl CoA
105
How many carbons are formed at the end of the first condensation reaction in the citric acid cycle?
2C + 4C=6C
106
What happens to the citrate in the citric acid cycle?
It is dehydrated then isomerism and hydrated again to form isocitrate
107
Why does citrate have to be dehydrated before it can be isomerased?
As the hydroxyl group isn't ideally located o the citrate from oxidative decarboxylation
108
Name the enzyme that catalyses the isomerisation and hydration of citrate
Aconitase
109
What happens to isocitrate once it has been formed?
It undergoes oxidative decarboxylation
110
Name the enzyme that catalyses the oxidative decarboxylation of isocitrate
Isocitrate dehydrogenase
111
What is formed when oxidative decarboxylation of the isocitrate occurs?
Alpha-ketoglutarat
112
What is special about the formation of a-ketoglutarat
The rate of formation of a-ketoglutarate determines | the overall rate of the citric acid cycle
113
What is special about the oxidative decarboxylation of isocitrate
It is the first 4 oxidation-reduction reactions and generates the first high transfer high potential electron carrier NADH
114
What happens after the oxidative decarboxylation of isocitrate ?
Oxidative Decarboxylation of succinyl coA | 5C to 4C
115
What happens after the Decarboxylation of succinyl CoA?
Substrate | level phosphorylation
116
What happens after substrate level phosphorylation
Oxidation
117
Name the 3 steps that are irreversible in the citric acid cycle?
1. Citrate synthase 3. Oxidative decarboxylation of isocitrate 4. Oxidative Decarboxylation (5C to 4C)
118
Name the electron acceptor for the oxidation react in the citric acid cycle?
FAD as the reducing power of succinate isn't sufficient
119
How many ATPs are yielded in the TCA cycle?
2 ATPs
120
How many NADH are yielded in the TCA cycle?
6 NADH
121
How many FADH are yielded in the TCA cycle?
2 FADH
122
What does Aconitase do?
It catalyses the dehydration, isomerisation and hydration of citrate
123
What does Isocitrate dehydrogenase do?
It catalyses the the oxidative decarboxylation of isocitrate

2nd yr- IBMS- Respiration and metabolism (3 decks)

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