3.3 Carbohydrates

Question 1

What elements are found in carbohydrates?

Answer 1

Carbon
Hydrogen
Oxygen

Question 2

General formula of carbohydrates

Answer 2

Cx (H2O)y

Question 3

What is a monosaccharide?

Answer 3

A single sugar unit

Question 4

Examples of monosaccharides

Answer 4

Glucose
Fructose
Ribose

Question 5

What is a disaccharide?

Answer 5

2 monosaccharides joined together

Question 6

Examples of disaccharides

Answer 6

Sucrose
Maltose
Lactose

Question 7

What monosaccharides make up sucrose?

Answer 7

Fructose and glucose

Question 8

What monosaccharides make up maltose?

Answer 8

2 alpha glucose

Question 9

What monosaccharides make up lactose?

Answer 9

Galactose and glucose

Question 10

What is a polysaccharide?

Answer 10

Many monosaccharides joined together

Question 11

Examples of polysaccharides

Answer 11

Glycogen
Cellulose
Starch

Question 12

What are hexose monosaccharides?

Answer 12

They contain 6 carbons

Question 13

Example of hexose monosaccharide

Answer 13

Glucose

Question 14

What are pentose monosaccharides?

Answer 14

They contain 5 Carbons

Question 15

Eg of pentose monosaccharide

Answer 15

Ribose, Deoxyribose

Question 16

Two types of glucose

Answer 16

Alpha and beta glucose

Question 17

Difference between alpha and beta glucose

Answer 17

Alpha - OH on Carbon 1 is on the bottom

Beta - OH on Carbon 1 is at the top

Question 18

Properties of glucose

Answer 18

Polar and soluble in water, due to the hydrogen bonds between Hydroxyl groups and water molecules

Question 19

Why is the solubility of glucose in water important?

Answer 19

This means glucose can be dissolved in the cytosol of the cell

Question 20

Why is glucose a good source of energy?

Answer 20

When the bonds in glucose are broken, a lot of energy is released

Question 21

What is a hydrolysis reaction?

Answer 21

It breaks a chemical bond between 2 molecules, with the use of a water molecule

Question 22

What is a condensation reaction?

Answer 22

It joins 2 molecules together, forming a chemical bond, where a water molecule is eliminated

Question 23

What happens when 2 glucose molecules react together?

Answer 23

The two OH groups react together, forming a glycosidic bond - a type of covalent bond between Carbon 1 and 4, so it is called a 1-4 glycosidic bond

Question 24

Polysaccharides in starch

Answer 24

Amylose

Amylopectin

Question 25

How is amylose formed?

Answer 25

By condensation of alpha glucose molecules, forming 1-4 glycosidic bonds ONLY

Question 26

How does the structure of amylose relate to its function?

Answer 26

The angle of the 1-4 glycosidic bond means amylose twists to form a helix, strengthened by hydrogen bonds. This means the polysaccharide is more compact and less soluble than the glucose - so a good molecule for storage.

Question 27

What type of glycosidic bonds does amylopectin form?

Answer 27

1-4 and 1-6 glycosidic bonds

Question 28

How does the structure of amylopectin relate to its function?

Answer 28

It has a branched structure, which makes it compact and better for storage. Also, with branching, there are more free ends where glucose molecules can be added and removed. It is also insoluble.

Question 29

Equivalent of amylopectin in animals

Answer 29

Glycogen

Question 30

Differences between glycogen and amylopectin

Answer 30

Glycogen forms more branches, so it’s more compact and less space is required for storage, which is important as animals move around more.

Question 31

What is the monosaccharide in cellulose?

Answer 31

Beta glucose

Question 32

How do beta glucose molecules join together in cellulose?

Answer 32

Alternate beta glucose molecules turn upside down and join together

Question 33

Why do beta glucoses have to bond in a different way?

Answer 33

The OH groups are too far apart to form 1-4 glycosidic bonds otherwise

Question 34

What is the result of the beta glucoses bonding in a different way?

Answer 34

They cannot coil or form branches, so it’s a straight chain molecule

Question 35

How are fibres formed?

Answer 35

Cellulose molecules make hydrogen bonds with each other to form microfibrils Microfibrils join to form macrofibrils Macrofibrils join to form fibres

Question 36

Properties of fibres made of cellulose

Answer 36

Strong and insoluble