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Yr 1 PoM > Cell Metabolism I > Flashcards

Cell Metabolism I Flashcards

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1
Q

3 Main Stages of Cellular Metabolism:

A

1) glycolysis
2) TCA cycle
3) oxidative phosphorylation

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2
Q

Which stage produces most ATP?

A

oxidative phosphorilation

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3
Q

What are the waste products from Cellular Metabolism?

A

CO2

urea

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4
Q

What are the 6 types of reactions?

A

1) Group transfer (A + BX → AX + B)
2) Ligation requiring atp cleavage (A + B → A-B)
3) Isomerization (A → B)
4) Oxidative reduction (A + :B → :A + B)
5) Hydrolytic (B-C + H2O → B + C)
6) Addition/ removal of functional groups (double bonds)

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5
Q

Kinase is responsible for…?

A

Catalysing the transfer of phosphate groups from one molecule to another (group transfer)

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6
Q

2 main stages of glycolysis?

A
  1. Form a high energy compound (invest ATP)

2. Split a high energy compound (generate ATP)

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7
Q

Glycolysis Stage 1:
Equation
Type of Reaction

A

Glucose —hexokinase—> glucose-6-phosphate + H+

-Requires 1 ATP, which adds a phosphate to the glucose forming ADP

Group transfer

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8
Q

Glycolysis Stage 2:
Equation
Type of Reaction

A

Glucose-6-phosphate —-phosphoglucose isomerase—> fructose-6-phosphate

Isomerisation

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9
Q

Stage 3:
Equation
Type of Reaction

A

fructose-6-phosphate —-phosphofructokinase—-> fructose-1,6-biphosphate

Requires 1 ATP to form ADP

phosphofructokinase is key in the control of sugars entering glycolysis

Group Transfer

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10
Q

Why are stages 2 and 3 important?

A

To try and make the molecule symmetrical

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11
Q

Stage 4:
Equation
Type of Reaction

A

fructose-1,6-biphosphate —-aldolase—-> glyceraldehyde-3-phosphate + dihydroxyacetone phosphate

2 high energy compounds produced

Hydrolytic

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12
Q

Stage 5:
Equation
Type of Reaction

A

dihydroxyacetone phosphate —-triose phosphate isomerase(TPI)—> glyceraldehyde 3-phosphate

End up with 2x glyceraldehyde 3-phosphate (one from stage 4)

Isomerisation

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13
Q

Stage 5:
Equation
Type of Reaction

A

dihydroxyacetone phosphate —-triose phosphate isomerase(TPI)—> glyceraldehyde 3-phosphate

End up with 2x glyceraldehyde 3-phosphate (one from stage 4)

TPI deficiency is the only enzyme which is fatal if deficiency → death

Isomerisation

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14
Q

Stage 6:
Equation
Type of Reaction

A

This reaction occurs 2x:
glyceraldehyde 3-phosphate —-glyceraldehyde 3-phosphate dehydrogenase—-> 1,3-biphosphoglycerate

Requires 1 NAD+ and Pi to form NADH (per reaction)

Redox and group transfer

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15
Q

Stage 7:
Equation
Type of Reaction

A

This reaction occurs 2x:
1,3-biphosphoglycerate —-phosphoglycerate kinase—-> 3-phosphoglycerate

Requires an ADP which accepts a Pi to form ATP (per reaction)

Group transfer

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16
Q

Stage 9:
Equation
Type of Reaction

A

This reaction occurs 2x:
2-phosphoglycerate —-enolase dehydration—-> phosphoenolpyruvate + H2O

Group removal

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17
Q

Stage 9:
Equation
Type of Reaction

A

This reaction occurs 2x:
2-phosphoglycerate —-enolase dehydration—-> phosphoenolpyruvate + H2O

Group removal (also known as dehydration)

18
Q

Stage 10:
Equation
Type of Reaction

A

phosphoenolpyruvate –pyruvate kinase—-> pyruvate

Requires an ADP which accepts a Pi to form ATP (per reaction)

group transfer

19
Q

Net result of glycolysis per glucose molecule:

A
  • 2 ATP molecules (use up 2 in part 1 and produce 4 in part 2)
  • 2 NADH
20
Q

What are the 3 fates of pyruvate?

A

1) alcoholic fermentation
2) lactate production
3) acetyl CoA production

21
Q

Lactate Production:
Equation
Type of Reaction

A

pyruvate –LDH—> lactate (reversible)

NADH + H+ → NAD+

anaerobic when O2 is limiting factor

22
Q

why is it important to regenerate NAD+ in lactate generation and alcoholic fermentation?

A

-with NAD+ glycolysis is able to continue, in conditions of oxygen deprivation

23
Q

Why is creatine phosphate useful in muscles?

A

-the amount of ATP needed during exercise is only enough to sustain contraction for around one second so provides ATP for the second muscle contract

24
Q

Why can Acetyl CoA readily donate acetate to other molecules?

A

-the thioester bond is a high-energy linkage, so it is readily hydrolysed, enabling acetyl CoA to donate the acetate (2C) to other molecules

25
Q

PDH complex stands for?

A

Pyruvate dehydrogenase

26
Q

PDH is made up of?

A

Thiamine pyrophosphate is a cofactor

27
Q

Why is thiamine pyrophosphate useful in the PDH complex?

A

It readily loses the highlighted proton and the resulting carbanion attacks pyruvate

28
Q

Where is thiamine derived from?

A

vitamin b1

29
Q

What does deficiency of Vitamin B1/ thiamine cause?

Symptoms and which organ is more vulnerable?

A
  • damage to the peripheral nervous system, weakness of the musculature and decreased cardiac output
  • The brain is particularly vulnerable as it relies heavily on glucose metabolism
30
Q

Creatine Phosphate as a buffer:

Equation

A

creatine phosphate + ADP + H+ –CK→ creatine + ATP

creatine + ATP –CK→ creatine phosphate + ADP + H+

31
Q

Why is creatine phosphate useful in muscles?

A

-the amount of ATP needed during exercise is only enough to sustain contraction for around one second so provides ATP for the transfer of aerobic to anaerobic respiration

32
Q

Where does the Krebs/TCA cycle take place?

A

mitochondria

33
Q

Net products of TCA per glucose

A
  • 2 molecules of CO2 (waste) -3 molecules of NADH
  • 1 molecule of GTP
  • 1 molecule of FADH2
34
Q

why does the NADH produced in glycolysis need t to enter + NAD+ leave the mitochondria?

A

NADH → oxidative phosphorylation in the mitochondria

NAD+ → glycolysis

35
Q

Glycerol Phosphate Shuttle:

A

1) free glycerol 3-phosphate dehydrogenase in the cytoplasms transfers electrons from NADH to DHAP to generate glycerol 3-phosphate.
2) A membrane bound form of the same enzyme transfers the electrons to FAD. These then get passed to co-enzyme Q, part of the electron transport chain

36
Q

Transamination

A

An amine group is transferred from one amino acid to a keto acid forming a new pair of amino and keto acids
-formation of urea

37
Q

Malate-Aspartate Shuttle:

A

1) transanimation

2) then the malate and aspartate are moved across the membrane through proteins

38
Q

Generic mechanism for amino acids to enter glycolysis / TCA:

A

transanimation → ketogenic amino-acids → TCA

glycogenic a-a- → glucose production

39
Q

How many molecules does the degradation of all 20 amino acids result in?

A

7 molecules

40
Q

Protein metabolism involves which main type of reaction?

A

transamination

41
Q

How is Alanine metabolised?

A

Alanine (C3) undergoes transamination by the action of the enzyme alanine aminotransferase

42
Q

Why does decreased TCA activity increase chances of cancer?

A

it enhances aerobic glycolysis → lactate is generate even under high o2 levels

Yr 1 PoM (17 decks)

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