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MCD > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What are the three fates of pyruvate following glycolysis?

A

Enters the Kreb’s cycle as Acetyl CoA, concerted to lactate or ethanol

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2
Q

Where does the Kreb’s cycle take place?

A

In the matrix of the mitochondria

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3
Q

Where does oxidative phosphorylation take place?

A

In the inner membrane of the mitochondria

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4
Q

What is the name of the 15C compound that goes on to make cholesterol?

A

Farnesyl pyrophosphate (FPP)

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5
Q

Through which type of channels does K+ leave the cell during repolarisation?

A

Voltage gated potassium channels

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6
Q

Which of the following molecules can the brain use as fuel sources? Glucose, acetoacetate or fatty acids?

A

Acetoacetate

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7
Q

What is the main carbohydrate store of the body?

A

The liver

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8
Q

When muscle is respiring anaerobically, pyruvate is metabolised to which molecule?

A

Lactate

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9
Q

During times of prolonged fasting, what is produced?

A

Ketone bodies are produced from fatty acids

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10
Q

What is the isoelectric point?

A

The point at which the molecule has no charge

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11
Q

Which part of the zwitterion determines its chemical properties?

A

The R group.

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12
Q

Name the only achiral amino acid.

A

Glycine

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13
Q

Name some non-polar amino acids

A

Glycine and proline

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14
Q

Name some polar amino acids

A

Serine, Threonine, Tyrosine, Asparagine, cysteine

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15
Q

Name x2 basic amino acids and explain why they are basic?

A

Lysine and proline - are basic; they are always protonated

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16
Q

What is the name of the amino acid which forms disulphide bridges?

A

Cysteine

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17
Q

Name x1 hydrophilic amino acid

A

Glutamic acid

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18
Q

Name x1 hydrophobic amino acid

A

Valine

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19
Q

Which two amino acids are involved in sickle cell disease. What happens?

A

Glutamic acid switches to valine at position 6.

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20
Q

What is one way to separate proteins?

A

Electrophoresis

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21
Q

Sketch a trimeric peptide

A

Remember the NH2 and COOH terminals. x3 R groups on each amino acid

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22
Q

Can the peptide bond rotate?

A

No, but the central carbon in all amino acids can.

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23
Q

What is steric hindrance?

A

Molecular structure is too big for molecules to come close enough to react with one another.

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24
Q

Name x5 types of forces which pull a protein into shape

A

Covalent bonds, hydrogen bonding, Van der Waals, Ionic reactions, hydrophilic and hydrophobic bonds, steric hindrance

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25
Q

The Gibbs free energy for a single phosphoanhydride bond of ATP has a positive or negative value?

A

A negative value; ATP hydrolysis can couple energetically unfavourable reactions to more favourable ones.

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26
Q

What is the hydride ion (H-)?

A

H+ and 2 electrons.

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27
Q

Is glycolysis an aerobic or anaerobic process?

A

Anaerobic

28
Q

What are the five co-factors in the pyruvate dehydrogenase complex?

A

TPP, Lipoamide, FAD, co-enzyme A and NAD+

29
Q

What is substrate level phosphorylation and where is it seen?

A

When a phosphate is DIRECTLY added to ADP to form ATP - seen in glycolysis.

30
Q

Is the first step of glycolysis - glucose to glucose-6-phosphate irreversible or reversible?

A

Irreversible

31
Q

What is the name of the enzyme which catalyses the reaction from pyruvate to Acetyl CoA?

A

Pyruvate dehydrogenase

32
Q

During which stage of the Kreb’s cycle is GTP produced from GDP?

A

Succinyl-CoA to Succinate

33
Q

How many carbons are in a-ketoglutarate?

A

5C.

34
Q

Before amino acids are entered as subtrates into the TCA cycle, what must first occur?

A

Transamination of amino acids.

35
Q

Where does oxidative phosphorylation take place?

A

In the mitochondrial inner membrane

36
Q

Describe the two steps in which oxidative phosphorylation can be split into?

A
  1. The translocation of protons from mitochondrial matrix to the intermembrane space.
  2. Protons flow back into the matrix from the intermembrane space coupled with ATP synthase to make ATP.
37
Q

What is coenzyme Q also known as?

A

Ubiquinone

38
Q

Describe the structure of ATP synthase.

A

F0 and F1 domains - F0 is membrane bound and contains a pore for protons to move through. F1 is made up of alpha, beta and gamma subunits.

39
Q

What is the effect of oligomycin?

A

Binds to ATP Synthase stalk and blocks proton flow through

40
Q

How does Cyanide block ATP production?

A

Cyanide binds with high affinity to Fe3+ in the cytochrome oxidase complex = blocks electron flow through the respiratory chain = inhibits proton pumping and ATP production.

41
Q

What makes up the majority of the LDL?

A

Cholesterol esters

42
Q

What is steric hindrance?

A

When a chemical reaction cannot occur due to the structure of that molecule.

43
Q

Which is the largest human protein?

A

Titin

44
Q

What is the free Gibbs energy for the hydrolysis of ATP?

A

-31kJ/mol

45
Q

Crystallographic analysis of enzymes with and without substrate bound, support which model of enzyme function?

A

Induced fit theory

46
Q

How does the activation energy of glucose combustion compare with glucose metabolism?

A

Glucose combustion = high activation energy

Glucose metabolism = low activation energy

47
Q

Where does glycolysis take place?

A

Within the cytoplasm of the cell

48
Q

How does Orlistat work

A

Reduces fat absorption by inhibiting gastric and pancreatic lipase.

49
Q

What would Orlistat be used to treat?

A

Obesity.

50
Q

Where does the majority of the energy used up by the body come from?

A

Fatty acid oxidation

51
Q

The reaction from acetoacetate to acetone is a …… reaction

A

Decarboxylation

52
Q

What is the predominant energy source during fasting?

A

Ketone bodies

53
Q

Name the two enzymes required in fatty acid synthesis

A

Acetyl CoA decarboxylase

Fatty acid synthase

54
Q

What is the overall reaction for lipogenesis?

A 
Acetyl CoA (C2) + 7 Malonyl CoA (C3) + 14 NADPH +14 H+
> Palmitate (C16) + 7 CO2+ 6 H2O + 8 CoA-SH + 14 NADP+
55
Q

De novo synthesis of fatty acids is limited to which x3 tissues/organs?

A

Liver, adipose tissue and lactating breast.

56
Q

Name the enzyme which is mainly affected in fatty acid oxidation disorders

A

Dehydrogenases - MCADD - Medium chain Acyl Dehydrogenase deficiency. Autosomal recessive.

57
Q

Why is Carnitine required in fatty acid oxidation?

A

Carnitine is required to move the Acyl CoA from the intermembrane space into the matrix.

58
Q

A family of Acyl-CoA-dehydrogenases are required to catalyze the initial step in each cycle of β–oxidation.
True or false.

A

True.

59
Q

Which species gets shorter by 2C in beta oxidation cycle - acetyl CoA or acyl CoA?

A

Acyl CoA

60
Q

What are the three mechanisms the body will use during starvation?

A

Glycogen stores will be broken down to get glucose
Release free fatty acids from adipose tissue
Convert acetyl CoA to ketone bodies

61
Q

Why do we need gluconeogenesis instead of relying on glycogen stores alone?

A

Glycogen stores are exhausted quickly (12-18hrs).

62
Q

Is gluconeogenesis a direct reversal of glycolysis?

A

NO; Different enzymes are used.

63
Q

Name x3 substances which make provide glucose during gluconeogenesis.

A

Lactate
Amino acids
Glycerol

64
Q

Glycerol can be used to make which substance in the glycolytic pathway?

A

DHAP.

65
Q

Name x2 ketogenic amino acids

A

Acetyl CoA and acetoacetyl CoA

MCD (8 decks)

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