3.3 Carbohydrates

Question 1

What elements are carbohydrates made of?

Answer 1

C, H, O

Question 2

What is a polymer?

Answer 2

A molecule made up of many similar smaller molecules (monomers) bonded together

Question 3

What is the name of the monomers that make up carbohydrates?

Answer 3

Monosaccharides

Question 4

What is a monosaccharide?

Answer 4

A single sugar molecule

Question 5

Give 3 examples of monosaccharides?

Answer 5

Glucose, fructose, ribose

Question 6

What is formed when two monosaccharides are linked?

Answer 6

Disaccharide

Question 7

Give 3 examples of disaccharides

Answer 7

Lactose, sucrose, maltose

Question 8

What is formed when 3 or more monosaccharides are linked together?

Answer 8

Polysaccharide

Question 9

Give 3 examples of polysaccharides.

Answer 9

Glycogen, cellulose and starch

Question 10

What is the formula for glucose?

Answer 10

C6H12O6

Question 11

What type of monosaccharide is glucose? Why is this the case?

Answer 11

Hexose monosaccharide - glucose has 6 carbons

Question 12

What are the properties of glucose?

Answer 12

Polar, soluble

Question 13

How does the structure of glucose relate to its function?

Answer 13

Due to the solubility of glucose, it dissolves in the cell’s cytoplasm so can easily be transported

Question 14

What is a condensation reaction?

Answer 14

A reaction between 2 molecules resulting in the formation of a larger molecule and the release of a water molecule.

Question 15

What is a hydrolysis reaction?

Answer 15

Breakdown of a molecule into 2 smaller molecules requiring the addition of a water molecule.

Question 16

What is the name of the bond between glucose molecules?

Answer 16

Glycosidic bond

Question 17

What happens when two alpha glucose molecules are next to each other?

Answer 17

• The 2 OH/hydroxyl groups react
• 2H atoms + 1O atoms are removed from the 2 glucose monomers and join to form a water molecule
• 1,4 glycosidic bond forms between the 2 monomers, forming disaccharide maltose

Question 18

What does “1,4 glycosidic bond” mean?

Answer 18

There is a glycosidic bond between Carbon 1 of one glucose monomer and Carbon 4 of another glucose monomer

Question 19

What molecule do you get when glucose and fructose are combined?

Answer 19

Sucrose

Question 20

What molecule do you get when glucose and galactose are combined?

Answer 20

Lactose

Question 21

What is a pentose monosaccharide?

Answer 21

A monosaccharide with 5 carbons

Question 22

What is formed when many alpha glucose molecules are joined by glycosidic bonds?

Answer 22

Starch

Question 23

How is starch formed?

Answer 23

When many alpha glucose molecules are joined by glycosidic bonds

Question 24

What are the 2 molecules which starch is composed of?

Answer 24

Amylose + amylopectin

Question 25

How is amylose formed?

Answer 25

When alpha glucose molecules are joined only by 1-4 glycosidic bonds

Question 26

How is the structure of amylose related to its properties?

Answer 26

The angle of the bonds forming amylose means the molecule twists to form a helix, stabilised by H bonds within.
This makes amylose more compact (good for storage) and less soluble than glucose.

Question 27

How is amylopectin formed?

Answer 27

Formed by 1-4 glycosidic bonds between alpha gluc mlcs but also some 1-6 glycosidic bonds between alpha gluc mlcs formed by condensation reactions

Question 28

How does the structure of amylopectin relate to its

Answer 28

..

Question 29

What are the 2 key structural differences between amylose and amylopectin?

Answer 29

Amylose is unbranched, amylopectin is branched