Enzymes

Enzymes

​Catalase

​What are enzymes?

Nearly all chemical reactions in the body are catalyzed by proteins called enzymes.

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Enzymes can speed up reactions by a factor of many millions, but they cannot catalyse reactions that would otherwise not occur and can only increase it up to a point (Vmax).

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Enzymes catalyse both anabolic (building up) and catabolic (breaking down) reactions.​

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​Structure of enzymes

All enzymes are globular proteins.

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What are the properties of globular proteins?​

​Structure of enzymes

Globular proteins are compact, spherical and soluble in water due to the presence of hydrophilic R groups on the outside of the molecule.

​Structure of enzymes

The active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction.​

The active site is only a small part of an enzyme consisting of just 3 to 4 amino acids.

​Enzyme function

Enzymes control metabolic processes in the body.

Metabolic processes in the body are complicated often involving a sequence of reactions and they have to happen in the right sequence​

​Enzyme function

Enzymes ensure that this metabolic pathway happens in a particular sequence.

Multiple Choice

The sequence of amino acids is known as a proteins...

• Primary structure

• Secondary structure

• Tertiary structure

• Quaternary structure

Multiple Choice

Which type of bond holds the secondary structures of proteins in place?

• Hydrogen

• Ionic

• Disulphide bonds

• Hydrophobic interactions

Multiple Choice

Which type of protein are enzymes?

• Globular

• Fibrous

Multiple Select

Which of the following are properties of globular proteins?

• Insoluble in water

• Soluble in water

• Compact

• Spherical in shape

Multiple Choice

Which of the following structures forms the shape of an enzymes active site?

• Primary structure

• Secondary structure

• Tertiary structure

Multiple Choice

How many amino acids typically make up the active site of an enzyme?

• 1-2

• 3-4

• 5-6

• 7-8

​Enzyme function continued...

Enzymes can be grouped according to whether they are intracellular or extracellular

​Enzyme function

​Intracellular enzymes are produced and work INSIDE a cell

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Extracellular enzymes are produced inside the cell but are SECRETED from the cell and work elsewhere

​Extracellular enzymes

Some organisms e.g. fungi, secrete enzymes outside of themselves, onto food and then absorb the nutrients.

Maybe think twice before eating that mouldy cheddar…

​Enzymes and digestion

Other organisms (including humans), digest their food internally and absorb the food into their blood.

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Many of these enzymes are produced by specific cells, and then released into the stomach or small intestine.

​Why does bread get sweeter the more you chew it?

Amylase is produced by salivary glands and the pancreas (pancreatic juice is released into the small intestines).

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Amylase breaks down starch into maltose.

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Then maltase breaks down maltose into glucose.

​Trypsin

Trypsin is a protease.

It is made in the pancreas and released into the small intestines.

It breaks down proteins into smaller peptides that can then be broken down into amino acids.

What about intra-cellular enzymes?

​Can you think of any examples of where enzymes are made and used, inside a cell?

Enzymes and protection

Enzymes and protection

​Intracellular enzymes

Some enzymes are required to form polymers inside cells.

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Catalase is an intracellular enzyme that catalyses the breakdown of hydrogen peroxide (a toxic by-product of a number of metabolic reactions).

Multiple Choice

Which group of enzymes work inside a cell?

• Intra-cellular

• Extra-cellular

Multiple Choice

What are extra-cellular enzymes?

• Enzymes that are made and used outside of a cell

• Enzymes that are made inside a cell and then secreted

• Enzymes that are made and used inside a cell

Multiple Choice

Human digestion involves which type of enzyme?

• Intra-cellular

• Extra-cellular

Multiple Select

Amylase is made by...

• Small intestines

• Pancreas

• Salivary glands

Multiple Choice

Amylase breaks down starch into...

• Amylose

• Maltose

• Glucose

Multiple Choice

Which of the following is a protease enzyme?

• Catalase

• Trypsin

• Amylase

• Maltase

Multiple Choice

Where is trypsin used?

• The pancreas

• The small intestines

Multiple Choice

Which of the following is an intra-cellular enzyme?

• Catalase

• Amylase

• Trypsin

• Maltase