Applied Science Unit 3: Enzymes

What is an enzyme?

A protein molecule that acts as a catalyst in a biochemical reaction.

What are proteins made up of?

Amino acids.

What four chemical groups are attached to the central (alpha) carbon?

A hydrogen atom, an amino group, a carboxyl group, and a variable R group (side chain).

How many different R groups are there?

There are 20 different R groups, which means there are 20 different amino acids.

What are amino acids linked together by?

Peptide bonds.

What does a condensation reaction occur between?

Two amino acids.

What is produced in a condensation reaction?

Water.

What is a dipeptide formed by?

Two amino acids linked by a peptide bond.

What do three amino acids form?

A tripeptide.

What do many amino acids join to form?

A polypeptide.

What is a polypeptide with more than 50 amino acids called?

A protein.

What is an active site?

The part of an enzyme where the biochemical reaction takes place.

What is a secondary structure?

Where polypeptide chains form orderly shapes.

What are secondary structures held in shape by?

Hydrogen bonds between the -NH of one peptide link and the -C=O of another amino acid.

What is tertiary structure?

A three-dimensional shape of a secondary structure.

What does the tertiary structure give?

It gives the enzyme the shape of its active site.

What are the most common shapes of secondary structures?

Coiled α-helix and folded β-pleated sheet.

What does the active site consist of?

A small number of amino acids that form a specific shape because of the protein's secondary and tertiary structure.

When an enzyme catalyzes a reaction, where does it take place?

It takes place on the active site of an enzyme.

What do enzymes work specifically to do?

Catalyse one type of biochemical reaction.

In a biochemical reaction, what are substrates converted to?

They are converted into products.

What does the substrate bind to?

The active site.

What shape does the substrate have?

It has a complementary shape to the shape of the active site on the enzyme.

What happens after the reaction?

The product is released, and the active site is available to catalyze further reactions.

What happens to the active site if the temperature goes too high?

The hydrogen bonds will break, changing the shape of the enzyme and denaturing it.

What is a catalyst?

A substance that speeds up a reaction and is left unchanged at the end.

What are enzymes?

Biological catalysts.

What is the collision theory?

For a reaction to occur, the particles must collide and have enough energy to react.

What does the energy of the collision depend on?

It depends on the speed of the particles and the angle they collide.

What is the activation energy?

The minimum energy needed for particles to react.

Why does the enzyme lower the activation energy needed?

It increases the number of particles with the required energy to react, leading to more successful collisions and a faster reaction.

What is the catalytic activity?

The increase in the rate of a reaction caused by the inclusion of an enzyme.

What is the substrate?

The molecule that is affected by the activation of the enzyme.

What does denatured mean?

When the tertiary structure of the enzyme is changed.

How can enzyme reactions be measured?

By measuring a decrease in the substrate or an increase in the product.

Why must the initial rate of reaction be recorded?

To measure the rate before it decreases as the substrate is used up.

What does the enzyme need to work effectively?

Specific conditions.

What happens if the specific conditions are not present?

The enzyme-catalyzed reaction may slow down or might not work at all.

What is the optimum temperature?

The temperature at which each enzyme works fastest.

What happens as the temperature increases to the optimum temperature?

The reaction rate also increases.

What happens below the optimum temperature?

There is less energy, leading to fewer collisions and a slower reaction.

What happens above the optimum temperature?

The hydrogen bonds in the enzyme break, causing the enzyme and active site to lose their shape.

What do enzymes have?

An optimum pH.

What does pH affect on the active site?

The charge; changes in pH can prevent the substrate from binding.

What can the concentration of the enzyme and substrate affect?

The rate of reaction.

What happens if the concentration of the substrate is too high?

There will be no more active sites for them to bind to, and increasing substrate concentration will no longer affect the reaction rate.

What happens if the concentration of the enzyme is too high?

There are too many free active sites compared to substrate molecules, and the reaction rate no longer increases.