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Metabolism > Basics of metabolism > Flashcards

Basics of metabolism Flashcards

1
Q

Describe the substrates in metabolism

A

Reduced organic compounds

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2
Q

How is energy from substrates released in metabolism?

A

Oxidation

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3
Q

Describe the benefit of biological/in vivo oxidation

A

Can be controlled

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4
Q

Benefit of partial oxidation

A

Can have various intermediates and trap energy released

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5
Q

What does biological oxidiation usually produce and release?

A

Energy trapped often as ATP

Waste products usually H2O and CO2

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6
Q

What is catabolism?

A

Breakdown of compounds to release energy (oxidation)

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7
Q

What is anabolism?

A

Biosynthesis of compounds from small precursors

Consumes energy and requires reduction

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8
Q

Why is ATP useful?

A

Provides a short term way to trap energy, (universal cellular energy currency)

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9
Q

What is ATP complexed to?

A

Mg2+

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10
Q

How is energy stored in ATP?

A

In each of the phosphate=phosphate bonds

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11
Q

Why is there rapid ATP turnover in cells?

A

ATP only present in small amounts in cells so need to quickly regenerate to match cellular demand

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12
Q

What is the signal to drive ATP synthesis?

A

ADP (stimulates oxidation and substrate level phosphorylation to make more ATP)

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13
Q

True or false, low ATP stimulates new ATP production

A

False

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14
Q

Why is ATP hydrolysis (or ADP) sometimes necessary?

A

Drive reactions with positive delta G (coupled to the reaction to make delta G< 0)

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15
Q

What is ATP hydrolysis coupled to?

A

Energy requiring reactions

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16
Q

How are oxidation and reduction reactions linked?

A

Intermediate molecules store/donate electrons

e.g. NAD+/NADH, FAD/FADH2, NADP+/NADPH

17
Q

What is produced as compounds enter TCA cycle?

A

NADH, FADH2, CO2

18
Q

What is stored in reduce intermediates, what happens to these intermediates?

A

Electrons stored e.g. NADH or FADH2

They are reoxidised for ATP generation in ETC

19
Q

What allows controlled oxidation and reduction to occur in same cell?

A

Compartmentalisation

20
Q

Where are most NAD+ AND FAD found, why is this good?

A

Unreduced in mitochondria, so ideal for oxidative reaction

21
Q

Why is it important to control rate at which metabolic reactions proceed?

A

Ensure supply meets demand

Forward and reverse pathways not running simultaneously (futile cycling)

22
Q

What do points of metabolic control have in common

Irreversible?

A

Irreversible

Energy sensing (rate controlled by energy level in cells)

23
Q

Why is hydrolysis of AMP to ribose not used as a source of energy?

A

Phosphate ribose bond stores less energy

24
Q

What are short term ways that enzyme activity i.e. cell’s metabolism is controlled, how long do they take?

A

1) Allosteric control (millisecs)
2) Covalent modifications (secs-mins)
3) Translocation (move form one cell compartment to another)

25
Q

Explain what long term control of cellular metabolism would entail?

A

Transcription/translation (hours to days)

26
Q

How can transcription/translation offer long term control of metabolism?

A

Transcription upregulation or enzyme induction/supression.

Enzymes in pathway can be targeted together to change metabolic pathway.

27
Q

Where does regulation of a metabolic pathway often take place?

A

Early in linear pathway

At branch points

Reciprocally at bidirectional points (where different enzyme for forward and reverse reactions)

28
Q

What is lactate produced by?

A

Anaerobic respiration
Red blood cells
Renal medulla

29
Q

What happens to lactate in Cori cycle?

A

Transported in blood where converted to glucose, glucose released into blood then phosphorylated and broken down into pyruvate then lactate.

30
Q

How can metabolism be controlled extrinsically?

A

From signals originating outside the cell e.g. hormones

31
Q

Why do small changes in plasma hormone levels often have large effects on cell function?

A

Amplification cascades

32
Q

What is the human daily macronutrient intake and associated energy?

A

300g Carbohydrates: 2500kJ
100g Fat: 420,00kJ
100g protein: 100,000kJ

Metabolism (13 decks)

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