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Foundations Of Medicine 1 > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Anabolism

A

Absorption of molecules

  • requires ATP (endergonic)
  • reductive

Eg. ADP + Pi —> ATP

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2
Q

Catabolism

A

Breakdown of molecules

  • releases energy (exergonic)
  • oxidative

eg. ATP —> ATP + Pi

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3
Q

Where is glycogen stored

A

Muscle and liver

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4
Q

What are human’s primary energy source

A

Glucose

Oxidised to CO2 and H2O

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5
Q

Structure of ATP

A
  • 3 phosphate groups
  • One ribose sugar
  • One adenine

Adenosine triphosphate

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6
Q

What is glucose used for

A
  • Storage by glycogen/conversion to lipids
  • Pyruvate
  • Lactate
  • Ribose-5-phosphate
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7
Q

How does glucose get transported into cells

A

Via Na+/glucose symporters
Via passive facilitated diffusion glucose transporters

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8
Q

Where is GLUT1 present

A

Brain

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9
Q

Where is GLUT2 present

A

Liver
Beta-cells

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10
Q

Where is GLUT3 present

A

Brain

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11
Q

Where is GLUT4 present

A

Muscle
Adipose (fat) tissue

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12
Q

Where is GLUT5 present

A

Gut

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13
Q

Where does glycolysis occur

A

Cytoplasm

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14
Q

Phase 1 of glycolysis

A

Glucose —> fructose-1,6-biphosphate

2ATP—>2ADP

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15
Q

Phase 2 of glycolysis

A

Fructose-1,6-biphosphate —> 2x triose phosphates

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16
Q

Phase 3 of glycolysis

A

2x triose phosphates —> 2x pyruvate

4ADP—>4ATP
2NAD+—>2NADH + 2H+

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17
Q

Overall reaction of glycolysis

A

Glucose + 2ADP + 2Pi + 2NAD+ —> 2 pyruvate + 4ATP + 2H2O + 2NADH + 2H+

Not efficient for ATP production
Fast

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18
Q

What are the 3 control points in glycolysis

A

Hexokinase - substrate entry (glucose)
Phosphofructokinase - rate of flow (intermediate)
Pyruvate kinase - product exit (pyruvate)

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19
Q

Fate of pyruvate

A

Provides carbon to fuel TCA cycle in mitochondria

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20
Q

Fate of NADH

A

Carries H+ and e- to electron transport chain for ATP synthesis

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21
Q

Stages of respiration

A

Glycolysis
TCA cycle
Electron transport chain

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22
Q

Glycolysis ATP net gain

23
Q

What happens if oxygen isn’t present

A

Lactic acid cycle

Only glycolysis
- 2 pyruvate converted to 2 lactic acid by NADH

24
Q

Can we cells produce energy by …

A

High rate of glucose —> lactic acid

25
Where does TCA cycle take place
Matrix of mitochondria
26
Where does the electron transport chain take place
The inner membrane of mitochondria
27
Role of dehydrogenase enzymes
Remove H+ and e- from glycolysis intermediates and pass them to NAD (forming NADH)
28
How is acetyl-CoA formed
Pyruvate (3C) enters the matrix —> CO2 released —> acetyl group (2C) combines with coenzyme A to form acetyl coenzyme A
29
Describe stage 1 of TCA cycle
Acetyl-CoA (2C) + oxaloacetate (4C) —> Citrate (6C) 6C —> 4C (yields 2CO2 + 2NADH) 4C undergoes oxidation - yields NADH, FADH2 and GTP (energy) Oxaloacetate (4C) recreated - cycle repeats
30
All enzymes of TCA cycle are located in the mitochondrial matrix except succinate dehydrogenase located in …
The inner mitochondrial membrane
31
If supply of pyruvate/oxaloacetate is limited (eg. no glycolysis), what is acetyl-CoA diverted to
Ketones - emergency energy supply for brain during fasting/starvation/diabetes Long term accumulation—> death, coma
32
Each turn of the TCA cycle results in transfer of … to NAD+ to form NADH + H+ And the transfer of … to reduce FAD to FADH2
3 pairs of e- 1 pair of e-
33
One substrate level phosphorylation reaction results in the formation of …
GTP from GDP and Pi
34
Each molecule of glucose yields … (up to TCA cycle)
10NADH + 10H+ + 2FADH2 + 6CO2 + 4ATP 2ADP made in glycolysis (-2) 2ATP for each pyruvate made (2 made = 4) Total in glycolysis = 2 1GDP forms 1 ATP. 2 pyruvate means 2GDP Total in TCA cycle = 2
35
Net gain of how many ATP in TCA cycle
2
36
What is the final hydrogen ion and electron acceptor
Oxygen
37
Electrons from NADH and FADH2 are used to reduce O2 to …
H2O
38
The energy of electron transport is used to pump protons (H+) from the … to …
Mitochondrial matrix to the intermembrane space pH decreases in the intermembrane space, increases in matrix
39
Energy of electron flow is used to phosphorylate ADP to ATP True/false
False Energy of PROTON (H+) flow is used to phosphorylate ADP to ATP
40
When does oxidative phosphorylation stop
Without the presence of O2 That’s why we need to breathe oxygen
41
In oxidative phosphorylation, the phosphoryl transfer potential of NADH+ and FADH2 is converted into the electron transfer potential of ATP True/false
False In oxidative phosphorylation, the *electron* transfer potential of NADH+ and FADH2 is converted into the *phosphorl* transfer potential of ATP
42
A negative E’o means that the reduced form of X has a lower affinity for electrons than H2, and a positive E’o means the opposite True/false
True Strong reducers = more -ve Strong oxidisers = more +ve
43
How is the energy of electrons converted into the energy of ATP
Oxidative phosphorylation Consists of: - electron transport - ATP synthesis
44
Electron transport and ATP synthesis are catalysed by the same proton pumps True/false
False Different proton pumps
45
Describe electron transport
- electrons flow from NADH and FADH2 to O2 - respiratory chain - energy is used to pump H+ out of the matrix
46
Describe ATP synthesis
- electrochemical gradients of H+ across inner membrane - energy stored in this gradient can be used to synthesise ATP
47
What are cytochromes
Proteins which contain a haem group as a functional co-factor Haem contains Fe(II) which can take up/release electrons
48
How many multisubunit complexes are present in the inner membrane, and how many of these pump H+
4 present, 3 pump H+
49
Describe the electrochemical gradient between the intermembrane space and matrix
- more H+ in intermembrane space than matrix - electrical field forms. Matrix more -ve - H+ want to flow back into matrix - flow back is coupled to ATP synthesis
50
What do protons flow back into the inner membrane from intermembrane space via?
ATP synthase Intermembrane —> inner membrane —> matrix
51
What can inhibit the electron transport chain
Cyanide, azide and CO inhibit transfer of e- to O2 No ATP made
52
What is oxidative phosphorylation in simple words
- H+ is pumped through ATP synthase - O2 electrons and H+ flow to make H2O - flow of H+ makes ATP from ADP
53
How much ATP is yielded from 1 glucose molecule
30 to 32 Glycolysis = 2 TCA cycle = 2 Electron transport chain = 26 to 28
54
What metabolic properties of cancer are relevant to PET scans
High glucose up-take Lactate/lactic acid production

Foundations Of Medicine 1 (5 decks)

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