biological molecules

Question 1

what are the functions of carbohydrates?

Answer 1

• source of energy in respiration
• constituent of DNA, RNA & ATP
• building blocks for larger molecules (starch, glycogen, cellulose)

Question 2

what is the difference between alpha and beta glucose?

Answer 2

alpha: OH group below carbon-1
beta: above

Question 3

type of bond formed in condensation reaction of maltose?

Answer 3

alpha- 1,4 glycosidic

Question 4

what are maltose, sucrose and lactose made up of?

Answer 4

• maltose: glucose & glucose
• sucrose: glucose & fructose
• lactose: glucose & galactose

Question 5

what is the structure of starch like?

Answer 5

• mixture of amylose and amylopectin
• amylose: straight-chain of alpha glucose, linked by 1,4
• amylopectin: branched chain of alpha glucose, linked by 1,4 and 1,6

Question 6

what is starch solubility?

Answer 6

• amylose and amylopectin insoluble in water
• glucose monomers are soluble

Question 7

what is the structure of glycogen?

Answer 7

• storage form of glucose in animals
• branched (much more than amylopectin) and linked by alpha 1,4 and 1,6
• once capacity in liver is exceeded, excess glucose is converted into glycogen then into fat

Question 8

what is the structure of cellulose?

Answer 8

• made of beta glucose and found in cell walls
• every other monomer rotated 180o to form beta 1,4 glycosidic bonds in a condensation reaction
• parallel chains of beta glucose are cross-linked with hydrogen bonds
• provides rigidity and strength- form microfibrils

Question 9

function of chitin?

Answer 9

• exoskeleton of insects and cell walls of fungi
• waterproof, lightweight for flight

Question 10

functions of proteins?

Answer 10

• structure (eg. myosin in muscles)
• reactions (enzymes)
• transportation (haemoglobin)
• communication (hormones eg. insulin)
• defence (antibodies)

Question 11

bond formed between amino acids?

Answer 11

peptide