Carbohydrates - Biological Molecules

Question 1

What are carbohydrates

Answer 1

• Carbohydrates are molecules which consists only of carbon hydrogen and oxygen
• They are long chains of sugar units called saccharides.

Question 2

What is a monosaccharide and disaccharide

Answer 2

Monosaccharides a single monomer
Disaccharide is a pair of monomers

Question 3

How does a polysaccharide form

Answer 3

Combing many monosaccharides form a polysaccharides.

Question 4

What happens when all polysaccharides join together

Answer 4

Through a glycosidic bond which is formed in a condesation reaction all of these molecules join together.

Question 5

What is glucose

Answer 5

Glucose is a monosaccharide conatining six carbon atoms in each molecule and is the main substrate for respiration and therefore of great importance.

Question 6

What are the two isomers of glucose

Answer 6

Alpha and Beta glucose

Question 7

What are examples of disaccharides

Answer 7

Maltose
sucrose
Lactose

Question 8

How is maltose formed

Answer 8

Maltose is formed by the condensation of two glucose molecules

Question 9

How is sucrose formed

Answer 9

Sucrose is formed by the condensation of glucose and fructose

Question 10

How is lactose formed

Answer 10

Lactose is formed by condensation of glucose and galactose

Question 11

How is glycogen and starch formed

Answer 11

Glycogen and starch is formed by the condensation of alpha glucose

Question 12

How is cellulose formed

Answer 12

Cellulose is formed by the condensation of beta glucose.

Question 13

What is glycogen the main energy store in

Answer 13

Glycogen is the main energy store in animals and is formed from many molecules of alpha glucose joined together by 1,4 and 1,6 glycosidic bonds

Question 14

Why is glycogen having many branches a good feature for it

Answer 14

It has a large amount of side branches meaning energy can be released quickly as enzymes can act simultaneously on these branches. Moreover its large and compact molecule therefore maximising the amount of energy it can store.

Question 15

What is the purpose of starch

Answer 15

Starch stores energy in plants and is a mixture of two polysaccharides called amylose and amylopectin.

Question 16

What is the structure of amylose

Answer 16

Amylose is an unbranched chain of glucose molecules joined together by 1, 4 glycosidic bonds. Therefore amylose is coiled and very compact resulting in a large amount of energy storage.

Question 17

What is the structure of amylopectin

Answer 17

Amylopectin is branched and made up glucose molecules with a 1-4 and 1-6 glycosidic bond. Due to the presence of side branches these can be acted upon simultaneously by many enzymes and broken down to release energy.

Question 18

What are the key properties of starch

Answer 18

• It is insoluble so it will not affect cell water potential
• It is compact so a lot of energy can be stored in a small space and when hydrolysed the released alpha glucose can be transported easily.

Question 19

What is cellulose

Answer 19

Cellulose is a component of cell walls in plants and is composed of long unbranched chains of beta glucose which are bonded by glycosidic bonds.

Question 20

What are microfibrils

Answer 20

MIcrofibrils are are strong threads which are made up of long cellulose chains running parallel to one another that are joined by hydrogen bonds forming strong cross links.