Enzymes And Digestion

Question 1

What are enzymes

Answer 1

A biological catalyst that speeds up reactions without being used up itself

Question 2

What is a enzyme made of

Answer 2

Proteins

Question 3

How do enzymes work

Answer 3

The active site of an enzyme has a complimentary shape to a certain substrate meaning it is a tight fit allowing the enzyme to catalyse a reaction. The complimentary shape shows enzyme specificity, am enzyme will only work on one substrate.

Question 4

What is the maximum rate of enzyme activity described as

Answer 4

Optimum level

Question 5

What happens to enzymes and substrates at a low temp

Answer 5

They move slowly due to low kinetic energy. Therefore there is fewer collisions and enzyme activity is low

Question 6

At what temp does maximum enzyme activity occur

Answer 6

Optimum temperature

Question 7

What happens to an enzyme at higher temps than the optimum

Answer 7

They progressively denature. The higher temp changes the shape of the active site and it no longer fits the substrate

Question 8

Each enzyme has a optimum pH on either side of this optimum why do they work less well

Answer 8

The incorrect pH changes the shape of the enzymes active site causing the complimentary fit to be less effective slowly down the rate of activity

Question 9

What happens as more enzymes become available

Answer 9

More enzyme activity and concentration but it eventually will level off as the number of substrate molecules will become limiting

Question 10

What is a inhibitor

Answer 10

A molecule or substance that fits loosely into an enzymes active site- they may not be the exact fit but will fit well enough to prevent normal substrates from using the enzyme. This will reduce the speed of reaction as enzymes being used by inhibitors are inactive

Question 11

What is digestion

Answer 11

The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed

Question 12

What is absorption

Answer 12

The process in which small, soluble food molecules are transferred from the gut to the blood system. (In the ileum)

Question 13

What are enzymes needed for in the digestive system

Answer 13

To break down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood stream.

Question 14

Where does most digestion of food take place

Answer 14

In the stomach and the first part of the ileum

Question 15

What 3 enzymes are in the digestive system

Answer 15

Carbohydrase/ amylase

Protease

Lipase

Question 16

What does amylase digest and what are the products of digestion

Answer 16

Digests starch

Produces glucose and other sugars

Question 17

What does protease digest and what does it produce

Answer 17

Digests protein

Produces amino acids

Question 18

What does lipase digest and produce

Answer 18

Digests fat

Produces glycerol and fatty acids

Question 19

What is a catabolic reaction

Answer 19

Break down of large insoluble molecules into smaller soluble or molecules

Question 20

What is a anabolic reaction

Answer 20

Build up of large molecules from smaller ones

Question 21

What are enzymes made of

Answer 21

Amino acids, most a enzymes contain 100-1000 amino acids

The amino acids are joined in a long chain which is folded to produce a unique 3d structure

Question 22

What is carbohydrase digest and produce

Answer 22

Digests carbohydrates to produce simple sugars

Question 23

When a substrate collides with a molecule of the right enzyme and fits exactly into the active site what is this called

Answer 23

Enzyme-substrate complex

Question 24

Explain the mouth in digestion

Answer 24

Teeth grinds food to increase surface area for enzyme action

Saliva is added by the salivary glands

It contains mucus ti lubricate to make it easy to swallow

It contains a digestive enzyme salivary amylase which helps break down starch into glucose

Question 25

How does the food pass down the oesophagus

Answer 25

Wave of muscular contraction this is called peri stalsis

Question 26

Explain the stomach in digestion

Answer 26

It contracts rhythmically, mixing the food thoroughly, turning it into a thick liquid called chyme

Glands in the lining then produce gastric juice which contains:

Protease enzyme (pepsin) this breaks down proteins into amino acids
Hydrochloric acid makes the stomachs conditions very acidic which provides a optimum pH for pepsin functioning, also kills many potentially dangerous microbes that enter along with food

Question 27

What does the small intestine consist of

Answer 27

Duodenum and ileum

Question 28

Explain pancreatic juice in the first part of the small intestine (duodenum)

Answer 28

It’s a juice produced from the pancreas that is secreted into the duodenum. It contains amylase, protease, lipase, carbohydrase

Question 29

Explain intestinal juice

Answer 29

Produced by walls of the duodenum. Contains enzymes (amylase, protease, lipase and carbohydrase) to finish digestion process

Question 30

Explain bile in the small intestine / duodenum

Answer 30

Green liquid produced in the liver and stored in the gall bladder

It’s alkaline so helps neutralise the acidic food passing from the stomach (this makes the duodenum slightly alkaline)

Emulsifies fat, breaks down large fat globules into smaller fat globules. Therefore increases the SA for lipase enzymes to break fat down,

Question 31

Explain the ileum in diegetsion

Answer 31

2nd part of small intestine. More enzymes secreted to ensure small molecules are then absorbed into the blood by diffusion. Then when they’re in the blood they can be carried to wherever they are needed

Question 32

Why does the ileum have a large SA

Answer 32

Allows absorption to occur quickly and efficiently as if it wasn’t a large surface area some digested food might pass out of the body before it has the chance to be digested

Question 33

Features of the small intestine to have a large SA

Answer 33

6m long

Has folds and twists

The inner surface has millions of microscopic finger like projections called villi.

Question 34

The small intestine has a good blood supply explain…

Answer 34

Each villus has its own network of blood capillaries. These transport products of digestion away from the small intestine once they’ve been absorbed and is replaced with blood low in digested food molecules

Question 35

What does the good supply of blood to each villus ensure

Answer 35

A steep concentration gradient is maintained, therefore increases rate of diffusion and therefore food molecules being absorbed

Question 36

How are fats absorbed differently to other food molecules

Answer 36

They are not absorbed through the blood capillaries on each villus but through a lacteal inside each villi. A lacteal is part of the lymph system eventually the fat molecules are returned back into the blood stream

Question 37

Explain why the villi are thin

Answer 37

The surface of each villi is thin and permeable due to the wall only being one cell thick and the blood capillaries are also one cell thick

This makes it easier for dissolved food molecules to diffuse through to the blood capillaries as less distance to travel.

Question 38

Some food we eat is indigestible why is this

Answer 38

We don’t have the correct enzyme to digest it

Question 39

Un digested food can’t be absorbed in the ileum so it leave the ileum and enters

Answer 39

The colon (large intestine )

Question 40

What 3 parts is the large intestine made of

Answer 40

Colon, rectum and anus

Question 41

Explain what happens in the colon

Answer 41

Water is absorbed from undigested food back into the blood; colon has a large SA to do this

Question 42

Explain what happens in the rectum

Answer 42

Faeces compacted and stored until egested

Question 43

How are enzymes used commercially

Answer 43

May be used in biological washing powders. They are effective at breaking down a wide range of stains and also are thermostable meaning they work at a wide range of temperatures.

They may also be used in things like softening the centre of chocolates and lactose free products

Question 44

Explain Lactose free products

Answer 44

Immobilised enzymes are used to remove lactose from milk

Product is therefore not contaminated with the enzyme lactose intolerant people can’t have