A.1.2: Nucleic Acids

Nucleotide components

Phosphate group, pentose sugar, organic base

How does the phosphate group bind to the sugar?

Covalent bond: oxygen in phosphate binds to carbon in sugar

Condensation reaction

Joining two nucleotides

Hydrolysis

Breaking apart two nucleotides

How do organic bases in the double helix bond?

Hydrogen bond, creates the double helix

Key differences between DNA and RNA

• Ribose instead of deoxyribose

• Single-strand rather than double

• Uracil instead of Thymine as an organic base

What is the difference between ribose and deoxyribose?

Ribose has 1 more oxygen molecule

mRNA

Carries genetic information out of the nucleus, from the DNA to the ribosome. mRNA codons guide the assembly of amino acids into a polypeptide.

tRNA

Transfers the correct amino acids into an ongoing chain to synthesise a specific protein. Brings amino acids to the mRNA or ribosome.

rRNA

Belongs in the ribosome, joins tRNA and mRNA and provides structural framework for the new protein.

Triplet codon

Three-base sequence coding for amino acids

Stop-codon

UAA, UAG, UGA

5’ (prime) end

Beginning end of a single DNA or RNA strand, unbound phosphate

3’ (prime) end

End of a single DNA or RNA strand, unbound pentose sugar

Percentage difference in DNA between humans

1%

Why do nucleotide polymers have a strong backbone?

Covalent sugar-phosphate bonds

DNA unity of life

All living things use DNA as their genetic material, suggests one common ancestor

Virus genetics

They are not living beings, they only exist to procreate and cannot live outside of a host organism. Some use DNA and some use RNA as their genetic code.

Which nitrogenous bases bond together?

A-C, T-G, U-G