Biological Molecules

Question 1

What is the general formula of carbohydrates?

Answer 1

(CH₂O)n

Question 2

Describe what is meant by a monosaccharide

Answer 2

A single monomer saccharide e.g. Glucose

Question 3

List some features of a glucose molecule

Answer 3

• 6 Carbon molecule (hexose sugar)
• ɒ and β glucose (OH on C1)
• Aldose sugar
• Has 4 chiral centres
• Has an enantiomer (is optically active)

Question 4

What are the two structural types of sugars?

Answer 4

Ketone based
CH2(OH)COCH2OH
ketose sugar

Aldehyde based
CHOCHOHCH2OH
aldose sugar

Question 5

What are the two enantiomers of sugars?

Answer 5

D or L

determined by the OH on the 5th Carbon being either on the left (L) or the right (D)

Question 6

How are disaccharides formed?

Answer 6

Via condensation reactions forming Glycosidic bonds between sugar molecules

Question 7

What are some features of Glycogen?

Answer 7

• Branched
• 1-4 ɒ Glycosidic bonds
• 1-6 ɒ Glycosidic bonds
• Easily broken down by enzymes
• Aldose sugar

Question 8

List the structural features of Starch

Answer 8

• 1-4 ɒ bonds

- not branched

Question 9

What is an oligosaccharide?

Answer 9

Saccharide polymers made of small numbers of monosaccharides and lipids

Question 10

Give an example of oligosaccharides

Answer 10

ABO blood groups

Question 11

What does the structure of an amino acid comprise of?

Answer 11

• Amine group NH
• Carboxyl group COO
• Variable side chain (R group)

Question 12

List some features of amino acid structure?

Answer 12

• 20 amino acids
• central carbon is chiral
• L-amino acids in organisms
  (bacteria cell walls made of D amino acids)

Question 13

What are amino acids the precursors of?

Answer 13

“Hormones

e. g.
- Tyrosine -> adrenaline
- Histidine -> Histamine”

Question 14

What are the components of a nucleotide?

Answer 14

• Sugar
• Phosphate
• Nitrogenous base

Question 15

List the structural differences between RNA and DNA

Answer 15

RNA

• ribose sugar
• A, U, G, C bases
• single stranded

DNA

• deoxyribose sugar
• A, T. G, C bases
• double stranded

Question 16

How is the DNA backbone formed?

Answer 16

“Nucleic acids made in a 5’ - 3’ direction, joining to alternating sugar
and phosphate molecules “

Question 17

Why is DNA more stable than RNA?

Answer 17

A single oxygen difference

Question 18

What are body fats made of?

Answer 18

Glycerol esters of fatty acids (triglycerides)

Question 19

Explain the structure of a phospholipid

Answer 19

Glycerol ester of two fatty acids and 1 phosphate group

Question 20

What is the arrangement of phospholipids in membranes?

Answer 20

Hydrophilic head sits on outside of the membrane

Hydrophobic tails hidden intracellularly

Question 21

When are micelles formed?

Answer 21

When phospholipids are submerged in water they form micelles

Question 22

How do proteins become non functional?

Answer 22

If proteins lose their structures due to mutations or denaturing

Question 23

Describe the effects of 3 single molecule diseases

Answer 23

Diabetes

• insulin dependent
• leads to failure of blood glucose regulation

Sickle cell disease

• haemoglobin aggregates into polymers
• due to change in 1 amino acid in a globulin chain

Cystic fibrosis

• absence of chloride ion transport protein
• leads to altered secretions