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A Level Biology - 2.1.4 Enzymes > Enzyme rates > Flashcards

Enzyme rates Flashcards

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1
Q

What are factors effecting rate of reaction?

A

Substrate concentration, enzyme concentration, temperature and pH

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2
Q

How does substrate concentration affect rate of collisions

A

If there are more substrate molecules per unit volume, there is more chance of each enzyme molecule to collide with substrate molecules per unit time.

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3
Q

How does rate of collisions affect rate of reaction on substrate concentration?

A

This causes more enzyme-substrate complexes to form per unit time, then more enzyme-product complexes to form per unit time to make more product per unit time so rate of reaction increases

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4
Q

What is point X?

A

The point of saturation

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5
Q

What happens at point X?

A

There are enough substrate molecules for each enzyme molecule to be occupied all the time and the enzyme is said to be saturated.

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6
Q

What happened up to point X?

A

Adding substrate always causes an increase in the reaction rate so the substrate is the limiting factor

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7
Q

What causes the rate of enzyme-catalysed reaction to not increase?

A

When there are enough substrate molecules to completely fill the enzyme active site

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8
Q

What is VMAX?

A

The maximal velocity which is the max rate of reaction under optimal conditions (temperature and pH) and excess substrate

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9
Q

What does VMAX reflect?

A

How fast the enzyme can possibly catalyse the reaction

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10
Q

What happens is substrate is continually added?

A

As enzyme concentration increases, so does the rate of reaction

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11
Q

What happens overall as temperature rises?

A

As temperature rises, the rate of reaction increases up to a certain point after which the temperature rise causes denaturation of the enzyme molecule.

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12
Q

How does temperature affect energy?

A

As temperature rises, kinetic energy increases so molecules move faster making collisions more likely between enzyme and substrate and have more energy.

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13
Q

What is the effect of enzymes being proteins?

A

There is an upper limit beyond which the enzymes tertiary structure becomes denatured and he enzyme becomes ineffective

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14
Q

What is Q10?

A

The temperature coefficient of a reaction which is how much the rate of reaction increases for every 10° rise in temperature

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15
Q

How do you calculate Q10?

A

The rate at one temperature divided by the second temperature which is 10 degrees before the first temperature

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16
Q

What does the number of Q10 mean?

A

If Q10 = 3, the reaction is tripling each time etc

17
Q

What does a change of pH result in?

A

A change in pH can cause a change in the conformation or shape of protein and enzyme activity is dependant on the enzyme shape so if the tertiary structure is altered, then the activity is affected

18
Q

Why is pH important to enzymes?

A

Most enzymes work in a narrow range of pH values and each enzyme has its own optimum pH

19
Q

What is the effect of slight change in pH

A

The rate of reaction can decrease but it does not denature the enzyme as it can reform once the pH is restored

20
Q

What does a large change in pH cause?

A

It may denature the tertiary structure of the enzyme

21
Q

How are pH buffers used?

A

To prevent the pH of a reaction changing

22
Q

What do changes in the pH causes?

A

Change in the H+ concentration which in turn will cause changes to the interactions between the R group in the active site and the substrate.

23
Q

What is pH?

A

A measure of the concentration of H+ ions in a solution and the tertiary structure of a protein is led together by hydrogen and ionic bonds

24
Q

Where is the site of action of saliva?

A

Mouth/throat

25
Q

What is the pH of saliva?

A

Neutral - 7-8

26
Q

What are the enzymes in saliva?

A

Amylase

27
Q

What is the function of saliva?

A

To break down starch -> maltose

28
Q

What is the site of action of gastric juice?

A

Stomach

29
Q

What is the pH of gastric juice?

A

Acidic - 1-2

30
Q

What are the enzymes in gastric juice?

A

Pepsin

31
Q

What is the function of gastric juice?

A

To break down proteins -> polypeptides

32
Q

What is the site of action of pancreatic juice?

A

Small intestine/deuodenum

33
Q

What is the pH of pancreatic juice?

A

Slightly alkaline - pH 8

34
Q

What are the enzymes in pancreatic juice?

A

Trypsin, lipase, amylase and maltase

35
Q

What is the function of pancreatic juice?

A

To break down proteins -> polypeptides, triglycerides -> glycerol + fatty acids, starch -> maltose and maltose -> glucose

A Level Biology - 2.1.4 Enzymes (5 decks)

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