Biological molecules

Question 1

Types of small molecule (micromolecule)

Answer 1

nucleotides, amino acids, monosaccharides, lipids/fats

Question 2

Roles of small molecules

Answer 2

1. Used as building blocks for large molecule (macromolecules)
2. Have some other specific function in their own right, e.g. Lipids associate to form membranes

Question 3

Types of large molecule

Answer 3

polysaccharides, proteins, nucleic acids (DNA and RNA)

Question 4

General formula of Carbohydrates

Answer 4

(CH2O)n

Question 5

Types of Carbohydrate

Answer 5

monosaccharides, disaccharides, polysaccharides, oligosaccharides

Question 6

Types of monosaccharide

Answer 6

Ketone based (Ketose) - contains the ketone functional group 
Aldehyde based (Aldose) - contains the aldehyde functional group

Question 7

Chirality of monosaccharides

Answer 7

Contain chiral centres which means they exist as Enantiomers. An enantiomer is one of the 2 opitical isomers of a chiral compound. They are non-superimposable (can’t produce same image if flipped onto one another) and rotate plane-polarised light in opposite direcetions.

Question 8

Glucose

Answer 8

Example of a monosaccharide.

An aldose

6 C-atoms: hexose

D-configuration: asymmetric C-atom most distant from the aldehyde/ketone group

Can exist in long-chain and ring structure

Question 9

Composition of sucrose

Answer 9

Glucose and Fructose

Question 10

Composition of Lactose

Answer 10

Glucose and Galactose

Question 11

Formation of disaccharides

Answer 11

Formed from condensation reaction between 2 monosaccharides which causes a glycosidic bond to form between them. Also causes H20 to be released once bond has formed.

Question 12

What is an Oligosaccharide?

Answer 12

Carbohydrate formed from a relatively small number of monosaccharides joined together by glycosidic bonds

Question 13

Glycosylation of oligosaccharides

Answer 13

Oligosaccharides can be covalently bonded to to an organic molecule (lipids or amino acid side chains in proteins) via N or O-linked glycosidic bonds to form structures like glycoproteins

Question 14

Oligosaccharides and blood groups

Answer 14

The ABO blood groups all contain antigens which are attached to oligosaccharides. These Oligosaccharides are covalently bonded to proteins/lipids within the red blood cell membrane. The specifc oligosaccharides bonded determine the blood group that red blood cell falls into.

Question 15

Structure of an amino acid

Answer 15

An alpha carbon (chiral carbon), carboxylic acid group, amino group and a radical side chain (R group)

Question 16

Types of amino acid

Answer 16

20 different amino acids within human genome. Can be either essential or non-essential

Question 17

Levels of protein structure

Answer 17

Primary structure: Covalent bonds forming polymer – e.g. order of amino acid residues joined by peptide bonds

Secondary structure: Regular folded form, often stabilised by hydrogen bonds – e.g. helices and sheets

Tertiary structure: Overall 3D structure, stabilised by hydrogen bonds, hydrophobic, hydrophilic and Van der Waal’s forces

Quaternary structure: Organisation of macromolecules into assemblies, often stabilised by same bonds present in tertiary structure – e.g. several polypeptide chains can make up a protein

Question 18

Nucleotide structure

Answer 18

Pentose sugar, nitrogenous base and a phosphate group

Question 19

Other functions of nucleotides

Answer 19

ATP: Energy unit
cAMP: Used as a secondary messenger in many biological pathways
AMP (Adenosine 5’- monophosphate): Involved in RNA synthesis

Question 20

Basic info on body fats

Answer 20

Mainly used as food reserves

Glycerol esters of fatty acids

Question 21

Basic info on fatty acids

Answer 21

Fatty acids can be saturated or unsaturated
Unsaturated fatty acids can have cis or trans configuration
Cis - H atoms on same side
Trans - H atoms on opposite sides

Question 22

How cholesterol intercalates into the membrane

Answer 22

1. OH interacts with the polar lipid head

2. Steroid scaffold interacts with the fatty acids