Enzymes

Question 1

Enzymes

Answer 1

Living things produce them which then act as biological catalysts.
Reduce the need for high temperatures and only have them to speed up the useful chemical reactions in the body

Question 2

Substrate

Answer 2

Molecule changes in the reaction

Question 3

Active site

Answer 3

Where the enzyme joins on to the substrate to catalyse the reaction

Question 4

What happens if the substrate’s shape doesn’t match the active site’s shape?

Answer 4

The reaction won’t be catalysed

Question 5

What affect the rate of reaction?

Answer 5

Temperature, pH and Substate concentration

Question 6

How does temperature affect the rate of reaction?

Answer 6

A higher temperature increases the rate at first.
If it gets too hot some of the bonds holding the enzyme break. This changes the shape of the enzyme’s active site.
The enzyme is denatured.

Question 7

How does pH affect the rate of reaction?

Answer 7

If it’s too high or low the pH interferes with bonds holding the enzyme together.
Denatures the enzyme

Question 8

How does Substrate concentration affect the rate of reaction?

Answer 8

The higher the substrate concentration the faster the reaction - more likely he enzyme will meet up and react with a substrate molecule.
Only up to a point. There are so many substrate molecules that the enzymes fill all of the active sites and adding more make no difference.

Question 9

Enzyme Practical (pH)

Answer 9

• put a drop of iodine solution into every well of a spotting tile
• put a Bunsen burner on a heat-proof mat, and a tripod and gauze over the Bunsen burner. Put a beaker of water on top of the tripod and heat the water until it’s 35°
• use a syringe to add 3cm(3) of amylase solution and 1cm(3) of a buffer solution with a pH of 5 into a boiling tube. Put the boiling tube into the beaker of water and wait for five minutes.
• use a different syringe to add 3cm(3) of a starch solution to the boiling tube
• mix the contents of the boiling tube and start a stop clock
• use continuous sampling to record how long it takes for the amylase to break down all of the starch, use a dropping pipette to take a fresh sample from the boiling tube every ten seconds and put a drop into a well. When it remains browny-orange starch is no longer present
• repeat the experiment with buffer solutions of different pH values to see how pH affects the time take for the starch to be broken down
• remember to control any variables each time (concentration and volume of amylase solution) to make it a fair test