Nucleotides and nucleic acids

Nucleotides

contain: pentose sugar, phosphate group and nitrogenous base

Nucleotides are linked by condensation reaction to produce phosphodiester bonds. The carbon 5 on one sugar covalent bonds with the OH on the carbon 3 of another. This creates a sugar-phosphate back bone. The bonds are broken by hydrolysis.

DNA

sugar= deoxyribose 

bases: pyrimidines: thymine and cytosine                                                                                           purines: adenine and guanine

made up of two strands of polynucleotides coiled in a double helix, with the strands running antiparallel to each other. 

between the strands the bases bond by hydrogen bonding. Adenine and thymine always bond together with 2 hydrogen bond. Guanine and cytosine always bond together with 3 hydrogen bonds. This is complementary base pairing. 

purification of DNA: macerate the tissue , add a strong detergent and then ethanol so that DNA precipitates out of solution. Can purify further by removing unwanted salts and then can concentrate.

RNA

sugar=ribose

bases: same except uracil instead of thymine (because less stable) 

made up of one strand and is usually shorter than DNA 

has three forms mRNA (messenger) tRNA (transfer) rRNA (ribsomal)

ATP + ADP

sugar=ribose

base=adenine

3 phosphate groups for ATP and 2 for ADP 

ATP is hydrolysised to realease energy and form ADP and a phosphate ion 

when fats and carbs get broken down the energy from it produces ATP by phosphorylation…