Biomacromolecules 2

Nucleic acids

• RNA and DNA. What’s the D and the R???

• Deoxyribonucleic acid• Ribonucleic acid

The sugars

The nucleotide monomer

Nitrogen base

HO H

C 5’ O

Negative charge

C 1’

C 2’C 3’

C 4’

Phosphate group

Phosphate Group

OH

P-O O

O

C 5’

What’s this?

Hydroxyl group!

Nitrogen base

HO H

5’ O

1’

2’3’

4’

OH

P-O O

ONitrogen base

HO H

5’ O

1’

2’3’

4’

OH

P-O O

O

How will they bond?

OH

Nitrogen base

OH

5’ O

1’

2’3’

4’

OH

P-O O

O

H

Nitrogen base

HO OH

5’ O

1’

2’3’

4’

P-O O

O

O

Phosphodiester bond. One ester bond was

there already. A new one has formed between the phosphate on the 5’ end and the oxygen on the

3’end.

What type of reaction is this?

Condensation polymerisation!

• Nucleotides can only be added to the 3’ end of the newly forming strand.

• This results in elongation of the new strand in a 5'-3' direction.

S sugar

P

B

Phosphate group

Nitrogen base

The molecule grows from the 5’ end to the 3’ end

Base PairingThere are 4 different bases in DNA .

• Adenine• Thymine• Guanine• Cytosine

• A always pairs with T and C with G

• A &T and C & G are complementary bases

• A & G are Pyrimidines• C & T are Purines

• Two hydrogen bonds form between A and T

• Three hydrogen bonds form between C and G

• DNA forms a double helix

• IN RNA, T is replaced by Uracil

DNA is an information molecule

• Information is carried in the order of the bases in DNA

• The information tells the cell which proteins to make

• The information is carried outside the nucleus by mRNA and proteins are built using tRNA and rRNA

• RNA is not a double helix

Lipids

• Fats, oils, waxes, steroids• Functions

– Energy storage– Structural components of

membranes– Transmission of chemical

signals within and between cells

• Lipids are not polymers

Triglycerides• Triglycerides have

a three (tri) fatty acid chains attached to a glycerol

• These are the fats used as energy stores

Only 3 OH groups so only 3 fatty acid chains. Not

polymers

Fat or oil?• Fats are solid at room temperature• Oils are liquid• This is determined by the structure of the fatty acid

chains• Saturated fatty acids have no double bonds in the

fatty acid chain (the chains are saturated with hydrogen atoms)

• Unsaturated have some double bonds• Unsaturated have some kinks in the fatty acids chains

Saturated Unsaturated

Cannot pack as tightly and so is liquid at higher temperatures

Phospholipids

• Phosphate is added to the glycerol instead of another fatty acid chain

• Phosphate group is polar, making it hydrophilic

• Fatty acid chains are non-polar and therefore hydrophobic

I water

I h8 water!

• Phospholipids will naturally form a bilayer in water

• The hydrophilic ends will point towards the water

• The hydrophobic ends will point to each other

Lets form a bilayer. It’s the only way to

keep both of us happy.

Glycolipids

• A carbohydrate group is added to the glycerol instead of a third fatty acid chain

• Project from plasma membranes and act as signal receptors

Steroids are lipids• Cholesterol is a

steroid• It is an important

structural component of many membranes

• It is the starting point for the synthesis of all steroid hormones e.g. oestrogen and testosterone

Group work

• Groups of 2• Each group do a different biomacromolecule• Heading will be your biomacromolecule• Content will be subunits, examples, function

where they’re found• Any other pertinent information• Include diagrams

Macromolecule Building blocks

Carbohydrates monosaccharides

Proteins Amino acids

Nucleic Acids nucleotides

Fatty acids and glycerolLipids

Examples

Glycogen, starch

Haemoglobin,