Biological Molecules

Question 1

What are the macromolecules for sugars, amino acids, nucleotides and lipids/fats?

Answer 1

Sugars = polysaccharides
Amino acids = proteins
Nucleotides = nucleic acids (DNA, RNA)
Lipids/fats = associate to form membranes

Question 2

What is the composition of a cell?

Answer 2

70% water
1% inorganic ions
3% small organic molecules
26% macromolecules

Question 3

What are the two types of monosaccharides?

Answer 3

Ketose - ketone based

Aldose - aldehyde based

Question 3

What monosaccharides form sucrose and lactose?

Answer 3

Sucrose - glucose and fructose

Lactose - glucose and galactose

Question 5

Explain the structure and functions of D and L isomers

Answer 5

Dextro isomers has the amine group on the left and carboxyl group on the right(NROC) and it’s residues are used to comprise cell walls of bacteria and is also often used in therapeutics
Levo isomers have the groups the opposite way round(CORN) and all amino acids incorporated into proteins by living organisms are in this form

Question 6

Describe the structure of glucose

Answer 6

4 chiral centres (therefore are enantiomers)
Aldose
Dextro if the hydroxyl group on the right of the penultimate carbon away from the aldehyde or ketone
Levo if the hydroxyl group is on the left of the penultimate carbon away from the aldehyde or ketone
Long chains and ring structures

Question 7

What is the difference between alpha and beta glucose?

Answer 7

Depends on the direction of the -OH group on carbon 1
Alpha = pointing down
Beta = pointing up

Question 8

Glycosylation

Answer 8

In which a carbohydrate is covalently bonded to an organic molecule to form structures like glycoproteins

Question 9

Glycogen

Answer 9

Branched
Aldose
1-4 alpha bonds 
Unable to form tight structures 
Easily broken down by enzymes

Question 10

Starch

Answer 10

Alpha 1-4 bonds

Not branched

Question 11

Cellulose

Answer 11

Beta glucose
Beta bonds
Straight structure 
Fibril structures 
Very strong so can’t be digested

Question 12

What is an oligosaccharide?

Answer 12

Carbohydrates composed of a relatively small number of monosaccharides

Question 13

How are peptide bonds formed?

Answer 13

Condensation reaction

Between amine group of one amino acid and carboxyl group of another

Question 14

What is a nucleotide made up of?

Answer 14

Sugar
Base
Phosphate

Question 15

Describe the structure of a nucleotide

Answer 15

Sugar - ribose or deoxyribose
Nucleic acids are made in 5’-3’ direction
Joined through a sequence of sugar-phosphate bonds
Bases are bonded by hydrogen bonds to form double helix

Question 16

Describe the structure of a triglyceride

Answer 16

Glycerol (Ester) head with 3 fatty acid tails

Hydrophilic head with hydrophobic tails

Question 17

Explain how single molecules cause diseases such as diabetes, sickle cell disease and cystic fibrosis

Answer 17

Diabetes - absence of protein hormone 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

Question 18

Body fats

Answer 18

Predominantly as food reserves
Glycerol esters of fatty acids
Unsaturated (trans) H atoms opposite
Unsaturated (cis) H atoms same side

Question 19

How does cholesterol integrate into the membrane?

Answer 19

OH group interacting with polar head

It’s steroid scaffold interacts with the fatty acids