ch.4 Nucleic acids & RNA world

• -polymers
• -come as RNA and DNA
• -RNA and DNA are made up of monomers known as nucleotides
• -ribonucleotides and deoxyribonucleotides

• -5 carbon sugar
• -phosphate group
• -nitrogenous base

• -Adenine(A),
• -Guanine(G),
• -Thymine(T) and
• -Cytosine(C).

Instead of Thymine it contains Uracil (U)

OH group on the 3rd carbon of the sugar joins the phosphate group on the 5th carbon of the sugar to form the phosphodiester bond.

• -double helix
• -sugar phosphate backbone
• -complementary base pairing (Watson Crick base pairing) : A-T and C-G
• -strands parallel to each other but run opposite (anti-parallel)

• -carries heriditary info in all living cells
• -The stability of DNA double helix, and accuracy of copying it make it the ideal molecule to carry hereditary information.
• -One DNA strand of the double helix is copied on to a messenger RNA molecule for protein synthesis. This is how the stored hereditary information in DNA is converted to function.

• -single stranded
• -pairing: A-U, G-C

can carry information, and it also has the catalytic ability. Catalytic RNA molecules are known as ribozymes. The ability of RNA to carry genetic information as well as its ability to function as a catalytic molecule make is the ideal candidate molecule that formed the first living thing.