B: Carbohydrates

Question 1

Carbohydrates

Answer 1

• contain the elements C H O
• general formula C_x(H₂O)_y

Question 2

Straight chain vs alpha-glucose

Answer 2

alpha-glucose —> Howarth projection

Question 3

Cyclisation of Monosaccharides

Answer 3

simple sugars are known as monosaccharides

carbon atom number 1 known as anomer –> originally part of the aldehyde group

Question 4

Formation of Disaccharides

Answer 4

• Disaccharides are formed when monosaccharides combine in a condensation reaction
  
  • water molecule will be eliminated in the process
• 1,4 glycosidic link formed

Question 5

Polysaccharides

Answer 5

• starch is used as carbohydrates storage in plants
• glycogen is used as carbohydrate storage in humans
• cellulose is used as structural material in plants and as dietary fibers as part of a balanced diet

Question 6

Functions of Carbohydrates

Answer 6

• Immediate supply of energy –> glucose
• Starch in plants –> reserve (short term)
• Glycogen in animals (short term)
• starting material for other complex materials

Question 7

Respiration and Photosynthesis

Answer 7

Respiration

C₆H₁₂O₆ + 6O₂ –> 6CO₂ + 6H₂O + ATP

^{adenosine triphosphate}

Photosynthesis

6CO₂ + 6H₂O —-> C₆H₁₂O₆ + 6O₂

^{light + chlorophyl}

• Cellulose is broken down by cellulase into glucose in animals
  
  • humans don’t have the enzyme –> still important as dietary fiber

Question 8

Hydrolysis of Starch

Answer 8

Starch ——–> Simple sugars

^{heat w/ dilute acid}

Benedicts solution - Test for reducing sugars

Two processes

1. Partition - depends upon the solubility in the mobile + stationary phase
2. Adsorption - sticking to the stationary phase

• Solvent is in the modile phase
• Polar water molecules –> stationary phase