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POM > Cellular Metabolism > Flashcards

Cellular Metabolism Flashcards

1
Q

How much free energy is required to hydrolyse ATP?

A

-31 Kjmol^-1

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2
Q

How much free energy is required for Glucose Combustion?

A

2872 Kjmol^-1

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3
Q

How much free energy is required for Glucose Metabolism?

A

-1178 Kjmol^-1

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4
Q

What is an oxidation-reduction reaction?

A

Electron transfer

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5
Q

What is ligation requiring ATP cleavage?

A

Formation of covalent bonds ie carbon carbon

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6
Q

What is isomerisation?

A

Rearrangement of atoms to form isomers

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7
Q

What is group transfer?

A

Transfer of functional group from one molecule to another

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8
Q

What is a hydrolytic reaction?

A

Cleavage of bonds by The addition of water

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9
Q

What is addition or removal of functional groups?

A

Addition to break a double bond or removal to form one

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10
Q

What reaction does hexokinase catalyse?

A

Glucose to Glucose-6-phosphate, produces H+ and ADP

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11
Q

How is Glucose-6-phosphate made? What is the significance of this step?

A

Glucose > Glucose-6-phosphate by hexokinase

Irreversible reaction, traps glucose inside cell by means of negative charge

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12
Q

What reaction does phosphoglucose isomerase catalyse?

A

Glucose-6-phosphate > Fructose-6-phosphate

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13
Q

How is Fructose-6-phosphate formed?

A

Glucose-6-phosphate > Fructose-6-phosphate via Phosphoglucose isomerase

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14
Q

How is Fructose-1,6-bisphosphate formed?

A

Fructose-6-phosphate > Fructose-1,6-bisphosphate via phosphofructo kinase
ADP is produced

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15
Q

What reaction does phosphofructo kinase catalyse?

A

Fructose-6-phosphate > Fructose-1,6-bisphosphate

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16
Q

What reaction does aldolase catalyse?

A

Fructose-1,6-bisphosphate into both Dihydroxy acetone phosphate and glyceraldehyde-3-phosphate

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17
Q

What is the role of TPI (triode phosphate isomerase)?

A

Dihydroxy acetone phosphate > glyceraldehyde-3-phosphate

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18
Q

What is the only glycolytic enzomyopathy that is fatal?

A

Deficiency in TPI, most die in the first 6 years

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19
Q

What is the role of G-3-P dehydrogenase?

A

Converts glyceraldehyde-3-phosphate into 1,3-biphosphoglycerate
Generates NADH

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20
Q

What is the role of Phosphoglycerate kinase?

A

1,3-biphosphoglycerate > 3-phosphopglycerate

Generates ATP

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21
Q

What is the role of Phosphoglycerate mutase

A

3-phosphopglycerate > 2-phosphpglycerate

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22
Q

What is the role of enolase?

A

2-phosphpglycerate > phosphoenal pyruvate

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23
Q

What is the role of pyruvate kinase?

A

Phosphoenal pyruvate > pyruvate

Generates ATP

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24
Q

What are the three products Pyruvate can form?

A

Ethanol
Lactate
Acetyl-CoA

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25
Q

How is ethanol made?

A

Pyruvate – (pyruvate decarboxylase)–> acetaldehyde – (alcohol dehydrogenase) –> ethanol
step 1 - H+ > CO2
step 2 - NADH + H+ > NAD+

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26
Q

How is lactate made?

A

Pyruvate – (Lactate dehydrogenase)–> lactate

NADH + H+ > NAD+

27
Q

How is Acetyl-CoA made?

A

Pyruvate + HS-CoA – (pyruvate dehydrogenase complex)–> Acetyl-CoA + CO2
NADH is generated
Commits the acetyl CoA into the TCA cycle

28
Q

What is the net result of glycolysis?

A

4 ATP and 2 NADH

28
Q

What is the net result of glycolysis?

A

4 ATP and 2 NADH

29
Q

Which two reactions generate NAD+ and why is this needed?

A

Alcohol fermentation and generation of lactate

Allows glycolysis to continue in time of oxygen depletion

30
Q
  • How much free energy is required to break down creatine phosphate?
A

-43 Kj/mol

31
Q

What is thiamine pyrophosphate a cofactor of?

A

The PDH (Pyruvate Dehydrogenase) complex - used to convert pyruvate to acetyl co A committing it to kerbs

32
Q

What condition does a deficiency in thiamine result in and what are the symptoms of this condition?

A

Beri-Beri

Damage to peripheral nervous system, weakness of musculature and decreased cardiac outpu

33
Q

What is the net result of the Krebs cycle?

A

3 NADH

2 CO2

1 FADH2

1 GTP

34
Q

What conditions does the Krebs cycle require?

A

Aerobic

35
Q

What are the steps of the krebs cycle?

A

Pyruvate > citrate > isocitrate > a-ketoglutarate > Succinyl CoA > succinate > fumerate > Malate > oxaloacetate > pyruvate
(Can i kill someone soon for my own pleasure?)

36
Q

What 7 molecules do all 20 amino acids degrade to?

A
  • pyruvate
  • Acetyle CoA
  • a-ketoglutarate
  • succinyl CoA
  • fumarate
  • oxaloacetate
37
Q

What is a glucogenic amino acid ?

A

An amino acid that when degraded its molecule can be converted into glucose

38
Q

Which two molecules do ketogenic amino acids degrade into?

A

Acetyl CoA and Acetoacetyl CoA

38
Q

Which 5 molecules do glucogenic amino acids degrade to?

A 
Pyruvate 
a-ketoglutarate 
Succinyl CoA
Fumarate 
Oxaloacetate
39
Q

Explain Transamination with an example

A

Allows production of non-essential amino acids by transferring amine group to keto acids

Alanine + alpha-ketoglutarate → pyruvate + glutamate
(Amine and oxygen switched to form glutamate and pyruvate)

Amino Acid —(NH4+)→ Keto acid Group Transfer

Pyruvate then enters Kreb’s cycle and glutamate is reconverted into alpha-ketoglutarate by glutamate dehydrogenase to form the amino group

40
Q

What is the purpose of the Glycerol Phosphate Shuttle

A

To carry electrons from NADH from the cytosol into the matrix of mitochondria in skeletal muscle and the brain

41
Q

Where in the body is the Glycerol-Phosphate Shuttle, used?

A

Skeletal Muscle

Brain

42
Q

Explain how the Glycerol-Phosphate Shuttle works

A
  1. Cytosolic glycerol-3-phosphate dehydrogenase transfers electrons from NADH to DHAP
    dihydroxyacetone phosphate > Glycerol-3-Phosphate
  2. membrane bound form of same enzyme transfers electrons to FAD to get passed to Coenzyme Q (part of the electron transport chain), also reforming DHAP
42
Q

Where in the body is the Malate-Aspartate Shuttle used?

A

Liver
Kidney
Heart

42
Q

How does the malate aspartate shuttle work

A

Aspartate — (aspartate transaminase converts a-ketoglutarate into glutamate)—> oxaloacetate —(malate dehydrogenase converts NADH to NAD+)—> malate
Malate is transported into the mitochondria by the malate-a-ketoglutarate antiporter

malate –(malate dehydrogenase converts NAD+ to NADH)—> oxaloacetate —(aspartate transaminase converts glutamate into a-ketoglutarate)—> Aspartate
Glutamate-aspartate antiporter takes aspartate into the cytosol

42
Q

What is the Warburg Effect?

A

Mutations in genes of Fumerase, Succinate dehydrogenase, Isocitrate Dehydrogenase, decreases Kreb’s Cycle activity which enhances anaerobic glycolysis

Preferential generation of lactate from glucose even in increased O2 availability

this can turn cells into malignant cancerous cells

42
Q

In which three areas can amino acids feed in to be metabolised?

A

Pyruvate, acetyl CoA or straight into the ETC

42
Q

What are the three basic steps for beta oxidation?

A
  1. make acyl CoA (outer mitochondrial membrane)
  2. transport Acyl CoA into the matrix via the carnitine shuttle
  3. beta oxidation itself
42
Q

Which transporter allows the carnitine shuttle to work?

A

Translocase

43
Q

What enzyme turns carnitine into acyl carnitine and which side does this occur?

A

Acyl transferase I
(acyl CoA > CoA)
Cytoplasmic side

44
Q

What enzyme turns acyl carnitine into carnitine and which side does this occur?

A

acyl transferase II
(CoA > acyl CoA)
matrix side

45
Q

What is used and generated in each beta oxidation cycle?

A

used - FAD, NAD+ and H2O

made - FADH2, NADH and acetyl CoA

46
Q

What is primary carnitine deficiency?

A

Autosomal recessive disorder
symptoms appear during infancy or early childhood and include encephalopathies, (cardiomyopathies, muscle weakness and hypoglycaemia)
Mutations in a gene SLC22A5 which encodes a carnitine transporter results in reduced ability of cells to take up carnitine needed for beta oxidation

47
Q

Name the four reactions in beta oxidation.

A

Oxidation
hydration
Oxidation
thialysis

48
Q

What are the four steps of fatty acid synthesis and which enzyme is used for it?

A 
CoA carboxylase Condensation 
ketoreductase Reduction  
dehydratase Dehydration
enolreductase Reduction 
crazy calm
Kangaroos run 
down ‘da’hills
every ramadan
49
Q

What molecules are first condensed in fatty acid synthesis? What product forms at the end?

A

Malonyl-CoA3 and activated acetyl group

forms activated acyl group linked to acyl carrier protein ( two carbon atoms longer)

50
Q

What are the three distinctions between fatty acid synthesis and degradation?

A

carriers- ACP v CoA
reducing power: NADPH v FAD/NAD+
location: Cytoplasm v mitochondrial matrix

51
Q

When does acetyl CoA generated by B oxidation enter the TCA cycle?
What happens if it doesn’t occur?

A

When b oxidation. and carbohydrate metabolism are. balanced
When fat breakdown predominates - ie during fasting- acetyl CoA forms acetoacetate, D-3-hydroxybutarate and acetone (ketone bodies)

52
Q

Describe the process of lipogenesis

A

FA are formed sequentially by decarboxylative condensation reactions, involving the molecules acetyl-CoA and malonyl CoA
Following a round of elongation, the FA undergoes reduction and dehydration by ketoreductase, dehydratase and enol reductase
The growing fatty acyl group is linked to an acyl carrier protein

53
Q

What enzyme catalyses the initial step in each cycle of beta oxidation within the mitochondrial matrix?

A

Acyl-CoA-dehydrogenase

54
Q

What is MCADD

A

medium chain acyl-coenzyme A dehydrogenase deficiency
autosomal recessive condition
patients should not go longer than 10-12 hours without food and adhere to a high carb diet

55
Q

Explain the process of ketone body formation?

A

Acetyl Co-A → acetoacetyl CoA → 3-hydroxy-3-glutaryl CoA → acetoacetate → D-3-hydroxybutyrate and acetone

POM (42 decks)

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