Factors Affecting the Rate of Enzyme-Catalysed Reactions (2.1.3)

HideShow resource information
What are the main factors that could affect enzymes?
Temperature changes. pH changes. Changes in substrate concentration. Changes in enzyme concentration. Presence of enzyme inhibitors.
1 of 10
How does low temperature affect enzyme activity?
At very low temperatures, rate of reaction is very low as enzyme & substrate molecules have little k.e so fewer ES complexes a second. As temperature increases, k.e increases and more collisions, so more product a second.
2 of 10
How do high temperatures affect enzyme activity?
Above the optimum, the enzyme denatures. The increase in k.e causes bonds to vibrate and break. Enzyme loses its shape.
3 of 10
Describe the process of denaturation.
Vibrations from increased k.e put strain on bonds. It breaks weaker bonds (H-bonds and ionic bonds). These bonds keep shape of active site. Rate of reaction decreases. Enough bonds broken, whole tertiary structure will unravel. Not reversible.
4 of 10
What is an optimum temperature?
The temperature at which an enzyme catalyses its reaction at its maximum rate.
5 of 10
What is pH a measure of?
The concentration of H+ ions in a solution.
6 of 10
How does pH affect enzyme activity?
It affects the bonds holding the shape of the enzyme. The H+ ions interfere with the H-bonds and ionic bonds, altering the active site shape. Most enzymes only work within a narrow pH range. Enzymes are only denatured by extreme pH changes.
7 of 10
What is the effect of increasing substrate concentration on enzyme activity?
As substrate concentration increases, more collisions with enzyme molecules per second-increases reaction rate. When all enzyme molecules in use, no more active sites. Substrate conc. being increased will make no difference.
8 of 10
What is the effect of increasing enzyme concentration on the rate of reaction?
In initial rate of reaction, there will be excess of substrate molecules. So increased enzyme concentration leads to more collisions with substrates per second. Therefore more ES complexes a second and this leads to an increased rate of reaction.
9 of 10
Why are enzymes usually maintained at low concentrations in cells?
They catalyse reactions very quickly and are re-used, so only a small amount is needed to meet demands.
10 of 10

Other cards in this set

Card 2

Front

How does low temperature affect enzyme activity?

Back

At very low temperatures, rate of reaction is very low as enzyme & substrate molecules have little k.e so fewer ES complexes a second. As temperature increases, k.e increases and more collisions, so more product a second.

Card 3

Front

How do high temperatures affect enzyme activity?

Back

Preview of the front of card 3

Card 4

Front

Describe the process of denaturation.

Back

Preview of the front of card 4

Card 5

Front

What is an optimum temperature?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all DNA, genetics and evolution resources »