B4 - Enzymes

Question 1

A catalyst is a substance that

Answer 1

changes the speed of a reaction making it faster

Question 2

Why are enzymes important in a living organism

Answer 2

Living cells use enzymes as catalysts to change the rate of reaction happening inside them.

Known as metabolic reactions (because they are reactions of the metabolism) which keep a living organism alive.

Without enzymes metabolic reactions would be too slow for life to carry on.

Question 3

Another name for enzymes

Answer 3

biological catalysts

Question 4

Enzymes are

Answer 4

proteins

Question 5

Enzymes can help

Answer 5

small molecules join together or help large molecules to break down into smaller ones

Question 6

The molecule that an enzyme joins with at the start of a reaction is called a

Answer 6

substrate

Question 7

The molecule that is formed at the end of a reaction in an enzyme is called the

Answer 7

product

Question 8

The enzyme shape matches the substrate shape and we call the shapes

Answer 8

complementary to each other.

Question 9

To increase the rate of reaction the reacting chemical (substrate) must bind to an enzymes

Answer 9

active site

Question 10

What is the active site

Answer 10

it is a region in the enzyme that fits and binds well with the substrate

Question 11

The active site fits the substrate to form a

Answer 11

enzyme-substrate complex

Question 12

Enzymes can catalyze many

Answer 12

substrate molecules making them reusable.

Question 13

Once a substrate forms into a product they

Answer 13

no longer fit within the active site and are released

Question 14

Enzymes are specific meaning

Answer 14

each enzyme only works with one substrate or a group of similar shaped substrates

Question 15

What are examples of some enzymes

Answer 15

Amylase - a type of enzyme that breaks down carbs into starch and simple sugars

Protease - digestive enzymes that break down protein into smaller units

Lipase - digestive enzymes that break down lipids

Question 16

Enzymes work most efficient in

Answer 16

optimum temperatures.

Question 17

What is the optimum temperature of a human enzyme that works near the core of the body

Answer 17

35 - 45 C

Question 18

What happens to enzymes in lower and higher temperatures

Answer 18

Lower: Enzymes in the body work more slowly as they have less kinetic energy meaning frequency of successful collisions between enzymes and substrates is reduced. Takes longer to start reactions

Higher: The structure of the enzyme will change as the bonds between enzyme molecules break, no longer fitting the substrate making it less efficient. It causes permanent damage and is said to be ‘denatured’

Question 19

An enzyme and substrate molecule can only form an enzyme substate complex when

Answer 19

they bump into each other with sufficient energy

Question 20

As temperature increases why does enzyme activity also increase

Answer 20

because the molecules gain more energy and move faster so the frequency of successful collisions between enzymes and substrates are higher meaning the rate of reaction increases.

Question 21

What are 4 factors that affect enzyme activity

Answer 21

Temperature
pH
Enzyme concentration
Substrate concentration

Question 22

Enzymes have an

Answer 22

optimum pH

Question 23

What happens to enzymes in lower and higher pH

Answer 23

lower: slows down rate of reaction of enzyme
higher: can denature the enzyme

Question 24

What happens when the enzyme is not in a suitable pH

Answer 24

The shape of the enzyme and its active site will change so that the substrate can no longer fit into it decreasing the rate of reaction.

Question 25

What are the steps and method for investigating the effect of pH on Amylase

Answer 25

Apparatus: Beakers, iodine solution, amylase, starch solution, pipette.

Steps:
Add amylase to starch solution
every 30 seconds take a drop of mixture and add to iodine solution
Record the time taken for iodine to stop turning blue (indicating starch has been broken down)
Repeat experiment with different levels of pH

The shorter time taken for iodine to stop changing color the faster the amylase has broken down the starch.

IV: Different levels of pH
DV: Time taken
CV: temperature needs to stay the same, enzyme and substrate concentration needs to stay the same. same number of drops of iodine solution
Safety precautions: Goggles of eyes, gloves for pH acidity.