Enzymes and digestion

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Slide 1

Topic: B2b Lesson: 2 Title: Enzymes and digestion

Aims: Explain how enzymes are involved in digestion

Starter: Write down everything you can remember from key stage 3 about digestion, eg. what it is; where it takes place .

Slide 2

What is digestion?

Breaking down large, insoluble molecules into smaller, soluble molecules that can be absorbed through the wall of the small intestine

What breaks down the large molecules?

Digestive enzymes made by specialised cells inside glands

Slide 3

The enzymes involved .

Carbohydrates Simple sugars

Proteins Amino acids

Lipids (fats) Fatty acids + glycerol

Slide 4

Digestion animation (First 5 mins 15 secs)

Listen carefully and make notes in your book. You will be quizzed after the animation so listen!

Slide 5

Mini test on digestive enzymes .

Where are the following digested:

Carbohydrates mouth and small intestine

Proteins stomach and small intestine

Fats small intestine

2. What are the following broken down into by digestive enzymes?

Carbohydrates  simple sugars

Proteins  amino acids

Fats  fatty acids + glycerol

3. Where are most enzymes produced? Pancreas

Slide 6

Why do you think there is acid in the stomach?

Kills bacteria in food – protects us

Denatures proteins – makes digestion easier

Activates stomach enzymes – these only work in acidic conditions

Ever wondered why PEPSIN (stomach enzyme) doesn’t digest our own stomach?

Pepsin is inactive when first made and is only activated by HCL to start digesting proteins.

Slide 7

What does bile do?

Bile is produced in the liver and stored in the gall bladder.

The enzymes in the small intestine need an alkaline pH to work best, so bile passes into the small intestine and neutralises acid from the stomach.

Bile also emulsifies fat droplets to increase their surface area

Slide 8

How are villi in the small intestine adapted to absorb food?

Slide 9

Slide 10

How are villi specialised to carry out their job of absorbing digested foods?