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Biology > Metabolic Pathways > Flashcards

Metabolic Pathways Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a metabolic pathway?

A

A series of enzyme-controlled reactions.

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2
Q

What does metabolism describe?

A

All the reactions taking place within a cell.

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3
Q

What are the two types of metabolic reactions?

A

Anabolic and catabolic

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4
Q

What is an anabolic reaction?

A

Build up complex molecules from simple building blocks.

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5
Q

What is a catabolic reaction?

A

Break down complex molecules into simple building blocks.

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6
Q

Do anabolic reactions require energy?

A

Yes

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7
Q

What is an example of an anabolic reaction?

A

Protein synthesis - amino acids are built up into proteins.

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8
Q

Do catabolic reactions require energy?

A

No - they release energy.

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9
Q

What is an example of a catabolic reaction?

A

Aerobic respiration - glucose and oxygen are broken down into carbon dioxide and water.

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10
Q

Give an example of how closely linked metabolic pathways are?

A

The energy generated by aerobic respiration (catabolic) is used for protein synthesis (anabolic).

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11
Q

How are metabolic pathways regulated?

A

By enzymes.

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12
Q

Can metabolic pathways be reversible?

A

They can be reversible, irreversible, or use an alternative route.

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13
Q

Give an example of a reversible metabolic pathway.

A

Fermentation in animals - when oxygen is present in lactate can be reversed back into pyruvate.

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14
Q

Give an example of an irreversible reaction.

A

Fermentation in plants and yeast.

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15
Q

What is the purpose of the cell membrane?

A
  • It controls the flow of materials into and out of the cell.
  • They also form the surfaces and areas where metabolic reactions can occur.
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16
Q

What are common examples of membrane-bound organelles?

A

Mitochondria and chloroplasts

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17
Q

What are the purposes of mitochondria and chloroplasts in terms of metabolic pathways?

A

They form compartments that keep metabolites close together or separated.

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18
Q

How many membranes do the mitochondria have?

A

It has a double membrane - inner and outer.

19
Q

Describe the inner membrane of the mitochondria.

A

It is folded to localise metabolic activity.

20
Q

Where is ATP found in plants?

A

In chloroplasts.

21
Q

What are the advantages of compartmentalised membranes?

A

Allows a high surface to volume ratio which allows high concentrations of substrates inside - leading to high reaction rates.

22
Q

What is the cell membrane made up of?

A
  • proteins

- phospholipids (type of fat)

23
Q

What is the benefit of the phospholipid layer in the cell membrane?

A

The bi-layer gives the membrane a fluid nature, making it flexible.

24
Q

What are the three main forms of proteins embedded in the cell membrane?

A
  • pores
  • pumps
  • enzymes
25
Q

What is the function of pores in the cell membrane?

A

Allows diffusion of specific molecules - larger molecules - across the membrane, through a channel.

26
Q

What is the function of pores in the cell membrane?

A

Act as carrier molecules to transfer specific ions against the concentration gradient - this is active transport and requires ATP.

27
Q

What is the function of enzymes in the cell membrane?

A

Speeds up the rate of biochemical reaction in the cell.

28
Q

What are enzymes?

A

Biological catalysts made up of protein, that speed up the rate of reaction.

29
Q

What controls the rate of a metabolic pathway?

A

Enzymes

30
Q

What is the activation energy?

A

The energy required to start the reaction.

31
Q

How do enzymes affect the activation energy of a reaction?

A

They lower the activation energy.

32
Q

Is the active site a rigid structure?

A

No, it’s flexible.

33
Q

What does ‘induced fit’ mean?

A

When the substrate enters the active site, they both change slightly to make the active site fit closely to the substrate molecule.

34
Q

Why is the induced fit useful?

A
  • ensures close contact between the active site and the substrate molecules
  • increases the chance of a reaction.
35
Q

What is the affinity of a molecule?

A

The tendency for it to bind to an enzyme.

36
Q

Describe the affinity in terms of a reaction.

A

Substrates have a high affinity for the active site, whereas products have a lower affinity for the active site and therefore separate.

37
Q

What is an inhibitor of a metabolic pathway?

A

A substance that decreases the rate.

38
Q

What are the three kinds of inhibitors of a metabolic reaction?

A
  • competitive
  • non-competitive
  • feedback
39
Q

How do competitive inhibitors work?

A

They have a similar shape to the substrate and are able to compete for the active site. They can bind to the active site and block substrates - reducing the reaction rate.

40
Q

How do you overcome competitive inhibition?

A

Increase substrate concentration

41
Q

How do non-competitive inhibitors work?

A

It binds to another part of the enzyme (not the active site), permanently changing the shape of the enzyme and active site, preventing the substrate from binding, and decreasing the rate.

42
Q

How do you overcome non-competitive inhibitors?

A

No way to reverse the effect.

43
Q

How does feedback inhibition work?

A

As the concentration of the end product builds up, some of it binds to the enzyme which slows down the reaction.

Biology (24 decks)

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