Nucleic acids

Nucleic acids

  • two types

    • RNA (ribonucleic acid)

    • DNA (deoxyribose nucleic acid)

  • DNA

    • stores genetic information

  • RNA

    • transfer of genetic information to protein

Properties of nucleic acid

  • DNA and RNA are polymers of nucleotides

    • polynucleotides

  • nucleotide - monomer

  • nucleotides

    • phosphate group

    • pentose sugar

    • organic nitrogenous base

    • formed by condensation reactions

    • condensation of nucleotides

Formation of nucleotides

  • condensation reactions

  • 4 different nucleotides can be formed

  • joined together by condensation reactions between the sugar and phosphate groups into chains of polynucleotides

    • phosphodiester bonds are formed

  • the order of the nitrogenous bases determine the genetic code

A polynucleotide

  • phosphodiester bond

  • polynucleotides can be broken down by hydrolysis reactions

  • the phosphodiester bonds are broken to release the nucleotides

  • polynucleotide

Structure of nucleic acids

  • RNA is single stranded

    • small so it can fit through the nuclear pores and leave the nucleus

  • DNA is double stranded

    • large to contain genetic information

    • made of two polynucleotide strands held together by hydrogen bonds

Complementary base pairing

  • the sugar phosphate backbone is on the outside

  • bases pair together on the inside

  • A pairs with T

  • C pairs with G

  • complementary base pairing

  • Purines

    • larger - A and G

  • Pyrimidines

    • smaller - T and C

  • purines and pyrimidines

  • strands are antiparallel

    • antiparallel strands

Polynucleotide direction

  • top phosphate is attached to carbon number 5 in the pentose sugar

    • 5’ end

  • bottom phosphate is attached to carbon number 3

    • 3’ end

  • polynucleotide direction