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Introductory Biochemistry > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What is metabolism?

A

The sum of all chemical reactions that take place in a cell or in an organism

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2
Q

Are metabolic pathways similar in diverse groups of organisms?

A

Yes, they are highly conserved. Indicates they evolved a long time ago

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3
Q

Does every organism have the same metabolic pathways?

A

No, some pathways like photosynthesis are limited to specific groups of organisms

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4
Q

What are the two purposes of metabolism?

A

To obtain energy from the environment

To create the molecules that cells require to live and grow

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5
Q

Where do photoautotrophs obtain energy and carbon from?

A

Energy comes from light, carbon comes from inorganic sources, namely CO2

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6
Q

Where do chemoheterotrophs obtain energy and carbon from?

A

Both from organic molecules

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7
Q

How is the chemical energy in organic molecules unlocked?

A

Breaking it down with aerobic respiration

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8
Q

What is catabolism? Is it oxidative or reductive? Exergonic or endergonic?

A

Breaking down molecules to obtain energy and building blocks. It is oxidative and exergonic and releases electrons and energy

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9
Q

What is anabolism? Is it oxidative or reductive? Exergonic or endergonic?

A

Building larger molecules from building blocks and energy. It is reductive and endergonic and requires an input of energy and electrons

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10
Q

What 3 biological macromolecules can be used as biological fuels?

A

Proteins, lipids, carbohydrates

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11
Q

What determines the direction and spontaneity of a reaction?

A

Free energy change: the DeltaG

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12
Q

When deltaG is negative:

a) which direction is spontaneous?
b) exergonic or endergonic?

A

Forward direction, exergonic

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13
Q

When deltaG is positive:

a) which direction is spontaneous?
b) exergonic or endergonic?

A

Reverse direction, endergonic. The forward direction requires energy input to go

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14
Q

When deltaG is zero:

a) which direction is spontaneous?
b) exergonic or endergonic?

A

Neither. The reaction is at equilibrium

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15
Q

What is the difference between deltaG° and deltaG°’?

A

deltaG°’ is the biochemical standard state, which also has the solute concentration at 1 mol/L, T = 298 K, P = 1 atm, but also has pH = 7

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16
Q

What is a metabolic pathway?

A

A series of consecutive, enzyme catalyzed steps

17
Q

Are the reactions in a metabolic pathway spontaneous?

A

Yes, they all have to be energetically favourable and directional

18
Q

What is the deltaG of a reversible reaction?

A

Close to 0

19
Q

What determines the direction of a reversible reaction?

A

The ratio of products to reactants

20
Q

What controls the rate of a reversible reaction?

A

The concentrations of reactants and products. The enzymes aren’t regulated

21
Q

What is the deltaG of an irreversible reaction?

A

Negative

22
Q

What controls the rate of an irreversible reaction?

A

They are regulated, and can be the rate limiting step that determines the overall rate of a reaction

23
Q

How can an enzyme catalyzing an irreversible reaction be regulated?

A
  • Amount of enzyme made or activated
  • Controlling enzyme activity
  • Controlling availability of substrate
24
Q

What are opposing pathways?

A

One pathway goes from A -> Z and the other goes from Z -> A

25
Q

How are opposing pathways regulated?

A

Reciprocally. When one pathway is operating the other is shut off

26
Q

How can an endergonic reaction be made to be energetically favourable?

A

Coupling it to a highly favourable reaction

27
Q

What are the molecules used to power an endergonic reaction?

A

High energy molecules

28
Q

What makes a molecule a high-energy molecule?

A

Increased resonance stabilization and decreased charge repulsion in the products compared to the reactants, which makes their breakdown favourable

29
Q

What are 4 common high energy molecules?

A

ATP, other NTPs, Acyl phosphates, thioesters

30
Q

Why is the breakdown of an acyl phosphate favourable?

A

Increased resonance in the products and the phosphate can be transferred to ADP to form ATP

31
Q

Why is the breakdown of a thioester favourable?

A

They are less stable than oxygen esters, so release more free energy when hydrolyzed

32
Q

What are cofactors and coenzymes?

A

Organometallic molecules that help with enzyme function

33
Q

Which two cofactors are used for electron transfer?

A

NAD+ and FAD

34
Q

What is the function of Coenzyme A?

A

Acyl group transfer to form thioesters

35
Q

Where do coenzymes come from?

A

Synthesized from vitamin precursors

36
Q

Why is glucose the preferred fuel despite fatty acids releasing more energy? 3 reasons

A
  1. It is water soluble, so can directly dissolve in the blood
  2. Fatty acids can’t cross the blood-brain barrier but glucose can
  3. Can be broken down in part anaerobically
37
Q

What type of cells can only use glucose as fuel?

A

Red blood cells

Introductory Biochemistry (16 decks)

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