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POM > Cell metabolism 1 > Flashcards

Cell metabolism 1 Flashcards

1
Q

What are the stages of cell metabolism?

A
  1. glycolysis
  2. TCA cycle
  3. Oxidative phosphorylation
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2
Q

Where does glycolysis occur?

A

Cytoplasm

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3
Q

Is glycolysis aerobic or anaerobic?

A

Anaerobic

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4
Q

What is the net gain of ATP and NADH in glycolysis?

A

2x ATP

2X NADH

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5
Q

What is the first step of glycolysis?

A

Glucose -> Glucose-6-phosphate

Enzyme: Hexokinase
ATP to ADP
Group transfer
Irreversible

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6
Q

What is the second step of glycolysis? (after glucose-6-phosphate)

A

glucose-6-phosphate -> fructose-6-phosphate

Enzyme: phosphoglucose isomerase
Isomerisation

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7
Q

What is the third step of glycolysis? (After fructose-6-phosphate)

A

fructose-6-phosphate -> fructose-1,6-bisphosphate

Enzyme: Phosphofructokinase
ATP to ADP
Group transfer

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8
Q

What is the fourth step of glycolysis? (After fructose-1,6-bisphosphate)

A

fructose-1,6-bisphosphate -> glyceraldehyde 3-phosphate + dehydroxyacetone phosphate

Enzyme: aldolase
Hydrolytic

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9
Q

Whats the 5th step of glycolysis? (After glyceraldehyde 3-phosphate + dehydroxyacetone phosphate)

A

dehydroxyacetone phosphate -> glyceraldehyde 3-phosphate

Enzyme: Triose phosphate isomerase
Isomerisation

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10
Q

Whats the 6th step of glycolysis? (after glyceraldehyde 3-phosphate)

A

glyceraldehyde 3-phosphate -> 1,3- bisphosphoglycerate

Enzyme: glyceraldehye 3-phosphate dehydrogenase
Nad+ + Pi to NADH
Redox and group transfer

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11
Q

Whats the 7th step of glycolysis? ( 1,3- bisphosphoglycerate)

A

1,3- bisphosphoglycerate -> 3-phosphoglycerate

Enzyme: phosphoglycerate kinase
Group transfer
ADP to ATP

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12
Q

Whats the 8th step of glycolysis? (after 3-phosphoglycerate)

A

3-phosphoglycerate -> 2-phosphoglycerate

Enzyme: phosphoglycerate mutase
Isomerisation

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13
Q

Whats the 9th step of glycolysis? (after 2-phosphoglycerate)

A

2-phosphoglycerate -> phosphoenolpyruvate (+H2O)

Enzyme: enolase
Dehydration reaction
Group removal

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14
Q

Whats the 10th step of glycolysis? (After phosphoenolpyruvate)

A

phosphoenolpyruvate -> pyruvate

Enzyme: pyruvate kinase
ADP to ATP
Group transfer

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15
Q

In what steps of glycolysis does ATP go to ADP?

A

Step 1

Step 3

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16
Q

In what steps of glycolysis does ADP go to ATP?

A 
Step 7 (x2)
Step 10 (x2)
17
Q

What are the 3 fates of pyruvate?

A
  1. Alcohol fermentation
  2. Lactate production
  3. Acetyl CoA production
18
Q

What happens in alcohol fermentation?

A

`Pyruvate -> Acetaldehyde -> Ethanol

1st enzyme: pyruvate decarboxylase H+ to CO2
2nd enzyme: alcohol dehydrogenase NADH + H+ -> NAD+

Characteristic of yeast
Anaerobic
REDUCTION

19
Q

What happens in lactate production?

A

Pyruvate -> lactate

Enzyme: lactate dehydrogenase
NADH + H+ -> NAD+
Reversible
Anaerobic
Characteristic of mammalian muscle
REDUCTION
20
Q

What happens in Acetyl CoA Production?

A

Pyruvate + HS-CoA -> Acetyl CoA + CO2

Enzyme: Pyruvate dehydrogenase complex
NAD+ -> NADH
Occurs in mitochondria
OXIDATION

21
Q

How is lactate dehydrogenase used as a diagnostic tool?

A

LDH is present in many body tissues
Elevated serum levels can be used to diagnose stoke and myocardial infarction
LDH can also be used to see which patients undergoing chemotherapy for follicular lymphoma will likely undergo relapse

22
Q

What is the outcome of the TCA/Krebs cycle?

A 
Each cycle produces:
2x CO2
3x NADH
1x GTP
1x FADH2
One cycle for each pyruvate
23
Q

What kind of reaction does protein metabolism require?

A

Transaminase reactions: amine group transferred from one amino acid to ketoacid forming new amino acid and ketoacid
Its a group transfer reaction

24
Q

What are the 7 molecules that all 20 amino acids can degrade into?

A 
Pyruvate
Acetyl CoA
Acetoacetyl CoA
Alpha-ketogluterate
Succinyl CoA
Oxaloactate 
Fumarate
25
Q

What happens to an amino acid once its entered the TCA cycle?

A

Amino group is removed (Excreted in urea) whilst C skeleton is funnelled into glucose production or Krebs cycle

26
Q

How does glucose metabolism differ in cancer?

A

Cells can use increased expression of glucose transporters to propel tumour growth e.g. GLUT-1

We can target GLUT-1 in treatment
Give patient radio labelled 18F glucose- this will accumulate in tissues with high expression of glucose transporters and can be used to locate tumour through imaging

27
Q

What are 2 ways in which electrons from NADH are transported to the mitochondrial matrix?

A
  1. Glycerol-phosphate shuttle

2. Malate- Aspartate Shuttle

28
Q

How does the glycerol-phosphate shuttle work?

A

For skeletal muscle and brain

Cytosolic glycerol-3-phosphate dehydrogenase transfers electrons from NADH to dihydroxyacetone phosphate to generate glycerol 3-phosphate

Membrane bound form of same enzyme transfers electrons to FAH, these then pass on to Co-enzyme Q

29
Q

How does the maltate-aspartate shuttle work?

A

For liver, kidney and heart

Also relies on cytosolic and membrane bound forms of these enzymes:
Aspartate transaminase
Malate dehydrogenase

Transamination reaction as well as redox reaction (NAD+ to NADH)

30
Q

What is beri beri?

A

A thiamine deficiency
Thiamine is a cofactor of pyruvate dehydrogenase complex
Deficiency of thiamine means difficulty to make acetyl CoA
Brain particularly vulnerable

31
Q

What are symptoms of beri beri?

A

damage to PNS
weakness of musculature
decreased cardiac output

POM (48 decks)

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