2.4 Factors Affecting Enzyme Activity Flashcards Preview

A Level Biology > 2.4 Factors Affecting Enzyme Activity > Flashcards

Flashcards in 2.4 Factors Affecting Enzyme Activity Deck (25):

Name 4 factors affecting enzyme activity:

• temperature
• PH
• enzyme concentration
• substrate concentration


What happens to the rate of reaction when temperature increases?

Rate of reaction increases


What does more heat provide the molecules with?

More kinetic energy


If the molecules have more KE what happens?

The molecules move faster


The faster the molecules (substrate) move what is more likely to occur?

collisions with enzymes, meaning there is more chance of a reaction


What does a rise in temperature do to enzyme molecules?

Makes them vibrate more


What happens with the vibrations if the temperature goes above a certain level?

The vibrations break some of the bonds that are holding the enzymes shape


What happens to the enzyme if bonds holding its shape are broken?

• active site changes shape
• substrate no longer fits
• enzyme is denatured


What is optimum temperature?

The temperature at which an enzyme works best (rate of reaction is highest)


What is the optimum temperature for most human enzymes?



At what ph do most human enzymes work best at?



What PH does pepsin work best at? Why is this useful?

• PH 2 (acidic)
• useful as it is found in the stomach


What happens to the H+ and OH- ions found in acids and alkalis above and below optimum PH?

• they can mess up the ionic and hydrogen bonds holding the enzymes tertiary structure in place


What does a change in the enzymes tertiary structure cause?

Change in the shape of the active site


What happens if the active site changes shape?

• enzyme and substrate no longer fit
• enzyme is denatured


What is more likely to happen the higher the enzyme concentration?

Collisions with substrate and the formation of enzyme-substrate complexes


What effect does increasing substrate concentration have on the rate of reaction?

• increased substrate concentration means increased rate of reaction


If the amount of substrate is limited what effect does increasing enzyme concentration have? Why?

• No effect
• because there is more than enough enzymes to deal with the available substrate


The higher the substrate concentration...?

The faster the rate of reaction


Why does increased substrate concentration mean increased rate of reaction?

There are more substrate molecules increasing the chance of collision between enzyme and substrate


What happens to the rate of reaction if you add more substrate after the saturation point?

• no effect on the rate of reaction


Why is there no effect on the rate of reaction when adding more substrate after the saturation point?

• too many substrate molecules
• all the enzymes active sites are full


How can you measure the rate of enzyme controlled reactions?

• speed of appearance of product
• the speed of disappearance of substrate


Give an example of an experiment for measuring the speed of product appearance?

• catalase catalysing the break down of hydrogen peroxide to oxygen and water
• collecting the oxygen produced whilst measuring how fast it is given off


Give an example of an experiment used to measure the disappearance of substrate?

• amylase catalysing the breakdown of starch to maltose
• detect starch using potassium iodide and iodine solution
• time how long it takes the starch to disappear

Decks in A Level Biology Class (102):