Carbohydrates

Question 1

What is the general formula for carbohydrates

Answer 1

Cx(H2O)y

Question 2

What are the 2 groups carbohydrates can be categorised in

Answer 2

• have an aldose group (contains aldehyde)
• have a ketose group (contains ketone)

Question 3

Outline the cyclisation of monosaccharides

Answer 3

• aqueous solutions
• The carbonyl group reacts with a hydroxyl group to form the ring structure, creating an ether linkage

Question 4

What are the exception to the cyclisation of monosaccharides

Answer 4

• triose (3) and tetrose (4)
• the bond angles between the carbons in the ring are very small which leads to a large amount of ring strain

Question 5

How are disaccharides formed

Answer 5

formed from monosaccharides
- condensation reactions

Question 6

What is the type of bond between glucose monomers

Answer 6

1,4 glycosidic linkage (ether)

Question 7

What are the 2 types of Linkages

Answer 7

• 1,4 linkage is when the bond is formed between the carbon 1 and carbon 4 (ex: amylose – soluble)
• 1,6 linkage is when the bond is formed between the carbon 1 and carbon 6 (ex: amylopectin – insoluble)

Question 8

List examples of polysaccharides and function

Answer 8

• cellulose: structural components of plants
• glycogen: energy storage in animals
• starch: energy storage in plants

Question 9

What are the properties of carbohydrates

Answer 9

• source of energy → glucose is converted to ATP
• polysaccharides are usually insoluble in water because they have non-polar (hydrophobic) regions + greater molecular mass
• they are easily oxidised

Question 10

Describe how Haworth projections help focus on the position of attached groups.

Answer 10

shows 3-D perspective of structures
- shows the cis and trans of groups

Question 11

Explain why a certain carbohydrate would be more water soluble than an another

Answer 11

• water solubility depends on the amount of H bonds formed with water
• if the carbohydrate has more oxygen or hydroxyl groups they are more soluble
• fewer O atoms and OH groups, they are less water soluble

Question 12

Explain why a certain carbohydrate would be more efficient at energy storage than another

Answer 12

• it is less oxidized
• the combustion of the compound is more exothermic per mole

Question 13

What are the monomers of carbohydrates

Answer 13

monosaccharides