NUCLEIC ACIDS

WHAT ARE NUCLEIC ACIDS?• Used for:• Storing genetic information• Assembly instructions for protein synthesis• Energy molecule (ATP – adenosine

triphosphate)

• Two major nucleic acid polymers:• DNA: deoxyribonucleic acid• RNA: ribonucleic acid

NUCLEIC ACIDS

DNA RNA

- Located in the nucleus - Located mostly in the cytoplasm

- Double-stranded, double helix structure

- Single-stranded structure

- Stable molecule - Less stable molecule

NUCLEOTIDES• Monomer of nucleic acids• Three components:

1. Phosphate2. Pentose sugar3. Nitrogenous base

NUCLEOSIDE

PENTOSE SUGAR

NITROGENOUS BASES

Purines

Pyrimidines

RNA DNA

PHOSPHODIESTER BOND• Phosphodiester bond formed between

nucleotides:• Pentose sugar (-OH group) • Phosphate group

‘BACKBONE’ OF DNA• Linking nucleotides

produces a single strand of DNA

• Phosphate + deoxyribose = backbone

COMPLIMENTARY BASE PAIRING

• Nitrogenous bases are joined through Hydrogen bonding

• Complimentary base pairs:• Adenine +

Thymine• 2 H bonds• Cytosine +

Guanine• 3 H bonds

ANTI-PARALLEL STRANDS• Complimentary base

pairing results in double-stranded DNA

• Both DNA strands run anti-parallel to each other (oriented in opposite directions)

One strand is 5’ 3’ while the other is 3’ 5’

COMPLIMENTARY BASE PAIRING

• The 2 anti-parallel strands coil together to form a double helix.

DOUBLE HELIX

OVERVIEW