Actions Of Enzymes

Question 1

what is an enzyme

Answer 1

Enzymes speed up chemical reactions by acting as biological catalysts.
They catalyse metabolic reactions
both at a cellular level (e.g. respiration) and for the organism as a whole
(e.g. digestion in mammals).

Question 2

Is catalase intracellular or Extracellular

Answer 2

Intracellular

Question 3

What does catalase do

Answer 3

Hydrogen peroxide is the toxic by-product of several cellular reactions.
If left to build up, it can kill cells.
Catalase is an enzyme that works inside cells to catalyse the breakdown of hydrogen peroxide to harmless oxygen
and water

Question 4

What do amylase and trypsin do

Answer 4

Amylase and trypsin both work outside cells in the human digestive system.

Amylase is found in saliva. It’s secreted into the mouth by cells in the salivary glands.It catalyses the hydrolysis (breakdown) of starch into maltose (a sugar) in the mouth

Trypsin catalyses the hydrolysis of peptide bonds - turning big polypeptides into smaller ones, Trypsin is produced by cell in the pancreas and secreted into the small intestine.

Question 5

Is amylase and trypsin intracellular or Extracellular

Answer 5

Extracellular

Question 6

What can Enzymes do to a cell

Answer 6

Enzymes can affect structures in an organism as well as functions

Question 7

What does intracellular mean

Answer 7

Within cells

Question 8

What does Extracellular mean

Answer 8

Outside cells

Question 9

What type of proteins are enzymes

Answer 9

Enzymes are globular proteins

Question 10

What is the structure of an enzyme

Answer 10

Enzymes have an active site, which has a specific shape. The active site is the part of the enzyme that the substrate molecules bind to.
The specific shape of the active site is determined by the enzyme’s tertiary structure

Question 11

Why does a substrate have to fit into the active site

Answer 11

For the enzyme to work, the substrate has to fit into the active site, its shape has to be complementary. If the substrate shape doesn’t match the active site, the reaction won’t be catalysed. This means that enzymes work with very few substrates - usually only one.

Question 12

What is the activation energy

Answer 12

In a chemical reaction, a certain amount of energy needs to be supplied to the chemicals before the reaction will start. This is called the activation energy - it’s often provided as heat.

Question 13

What happens when enzymes reduce activation energy

Answer 13

Enzymes reduce the amount of activation energy that’s needed, often making reactions happen at a lower temperature than they could without an enzyme. This speeds up the rate of reaction.

Question 14

How does an enzyme substantiate complex lower the activation energy

Answer 14

When a substance binds to an enzyme’s active site, an enzyme-substrate complex is formed. It’s the formation of the enzyme-substrate complex that lower the activation energy.

Question 15

Why does an enzyme substantiate complex being formed lower the activation energy

Answer 15

1)If two substrate molecules need to be joined, attaching to the enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily.

2) If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate.
This strain means the substrate molecule breaks up more easily.

Question 16

What is the lock and key model

Answer 16

Enzymes are a bit picky. They only work with substrates that fit their active site. Early scientists studying the action of enzymes came up with the ‘lock and key’ model. This is where the substrate fits into the enzyme in the same way that a key fits into a lock.

Question 17

Why did scientists modify the lock and key model for the induced fit model

Answer 17

Scientists soon realised that the lock and key model didn’t give the full story. The enzyme and substrate do have to fit together in the first place, but new evidence showed that the enzyme-substrate complex changed shape slightly to complete the fit. This locks the substrate even more tightly to the enzyme. Scientists modified the old lock and key model and came up with the ‘induced fit’ model.

Question 18

What is the induced fit model

Answer 18

The ‘induced fit’ model helps to explain why enzymes are so specific and only bond to one particular substrate.

The substrate doesn’t only have to be the right shape to fit the active site, it has to make the active site change shape in the right way as well.

Question 19

What is the enzyme substrate complex

Answer 19

Enzyme has a specific shape, so it only works with specific substrates that fit the active site