BY1: Nucleic Acids

Consists of:
-A phosphate group.
-A pentose sugar.
-Organic base (contains N); Pyrimidine - T and C, Purine - A and G. 

-Double stranded polymer.
-Each polynucleotide may contains millions of units.
-Double helix held together by hydrogen bonds.
-The pentose sugar is deoxyribose.
-Four bases: Thymine, Cytosine, Guanine, Adenine.
-Linked by compementory base: A-T, C-G.
 

-Very stable so can pass from generation to generation without change. 
-Very large and can carry large amounts of genetic information.
-Two strands are held by H bonds, easy to break for transcription.
-Sugar-phosphate backbone protects information.  

-Single stranded.
-Pentose sugar is ribose.
-The bases are the same but Thymine is replaced by Uracil.

-mRNA: A long molecule in a single helix, made in the nucleus, for carrying code into cytoplasm.
-rRNA: Large, complex molecule, with both single and double helices; ribosomes are made up of rRNA and protein, and is the site of translation.
-tRNA: Single stranded in a clover shape, with one end where the amino acid is carried and the other end is called the anticodon; transporting amino acids to ribosomes. 

DNA:
-Sugar = Deoxyribose
-Bases = CGAT
-Helix = Double

RNA:
-Sugar = Ribose
-Bases = CGAU
-Helix = Single