Lecture 2 - Biological Molecules

Question 1

Condensation reaction

Answer 1

Reaction that occurs when two molecules are joined together with the removal of water

Question 2

Hydrolysis reaction

Answer 2

Reaction that occurs when one molecules is split into two smaller molecules with the addition of water

Question 3

Composition of a cell (4)

Answer 3

Water 70
Inorganic ions 1
Small Organic molecules 3
Macromolecules 26

Question 4

Two types of monosaccharides

Answer 4

Aldehyde - Aldose

Ketone - Ketose

Question 5

General formula of carbohydrates

Answer 5

Cx(H20)y

Question 6

Glucose (5)

Answer 6

4 chiral centres
Forms enantiomers
Can be either D (right) or L (left) depending on where -OH group is placed on 5th carbon
D glucose gives a and b glucose.
a glucose when -OH pointing down on carbon 1

Question 7

How is glucose suited to its function (4)

Answer 7

Soluble- easily transported around.
Small molecules – can diffuse across cell membranes.
Easily/quickly, respired/oxidised to produce ATP.
Can form maltose and glycogen.

Question 8

Examples of Disacccharides (4)

Answer 8

Maltose (malt sugar) = α glucose + α glucose
Sucrose (milk sugar) = α glucose + fructose
Lactose (milk sugar) = α glucose + β galactose
Cellobiose = β glucose + β glucose

Question 9

Oligosaccharides - BREAK DOWN THE NAME
- definition - 2 functions
(4)

Answer 9

Is a saccharide polymer containing a small number of monosaccharides
Monosaccharides and lipids - blood groups
Cell recognition
Cell binding

Question 10

Amino acids (7)

Answer 10

Chiral carbon
D (right) or L (left) form (L form are only used and formed in cells). Some D in walls of bacteria
D amino acids are used in therapy
Except glycine (R group is a H)
Peptide bonds and condensation reaction 
Precursors to hormones

Question 11

AA Precursors to hormones

Answer 11

Tyrosine —> Adrenaline (triggers glycogen breakdown)

Histidine —> Histamine (vasodilator)

Question 12

Nucleic acids (6)

Answer 12

Sugar, base and phosphate 
Pyrimidines (single ringed) - T and C
Purines (double ringed) - A and G
2 - A and T. 3 - G and C.
Nucleic acids made in 5’ to 3’ end
Bases joined by hydrogen bonds

Question 13

Lipids

Answer 13

Ester bonds/ esterification

Question 14

Esterification

Answer 14

A condensation reaction where -OH group of a carboxylic acid and the -OH of an alcohol produce an Ester.

Question 15

Define triglyceride (1)
Functions of triglycerides (5)

Answer 15

One glycerol and three fatty acids (members of carboxylic acids)
Energy store
Energy source
Insulation
Buoyancy
Protection

Question 16

Phospholipids

Answer 16

2 fatty acids and a phosphate
Hydrophobic tail
Hydrophilic head

Question 17

Cholesterol

Answer 17

Decreases fluidity of membrane
Increases flexibility of membrane
Reduces permeability for solubility molecules

Question 18

Diseases caused by a single molecule (3)

Answer 18

Diabetes (insulin-dependent): Absence of protein hormone (insulin) leads to failure to regulate blood glucose.
Sickle cell disease: One amino acid change in a globin chain causes haemoglobin to aggregate into a polymer.
Cystic fibrosis: Absence of membrane protein that transports chloride leads to altered properties of secretions.