nucleic acids

nucleotides

C, H, O, N, P

• contains phosphate group, pentose sugar (deoxyribose/ribose) and nitrogenous base • forms phosphoester bond between carbon 5 of pentose sugar and phosphate group

adenine and guanine

thymine and cytosine

• forms via condensation reactions, releases water molecule phosphodiester bond forms between the hydroxyl group on carbon 3 of the pentose sugar of one nucleotide and the phosphate group on another nucleotide

• double helix strand • two polynucleotide chains held together by hydrogen bonds between complementary base pairs (adenine and thymine , cytosine and guanine) • phosphodiester bonds form between each nucleotide • polynucleotides form sugar phosphate backbone, consisting of a phosphate group, nitrogenous base and deoxyribose sugar • strands are anti-parallel

• contains ribose sugar • contains bases = adenine, cytosine, guanine and uracil

• dna found in chromosomes in nucleus whereas RNA found in cytoplasm • dna is a long molecule, rna is much shorter • dna is a double strand, rna is a single strand • dna contains thymine whereas rna swaps thymine for uracil

• dna helicase breaks hydrogen bonds between base pairs, unzipping the dna and separating the strands • original strand acts as a template • free nucleotides match up with their complimentary base pair, forming hydrogen bonds between them • dna polymerase forms phosphodiester bonds between nucleotides via condensation reactions • dna consists of an original and new strand

• ## can only function in the 5 to 3 direction

crick and watson

each replicated dna molecule contains one original stand and one new strand

bases contain nitrogen, bacteria would use it to form new dna

• gen 0 only given nitrogen 15, therefore when replicating, dna only consists of dna 15. When centrifuged, one line low down as it is only one dna type and is dense • gen 1 given n 14, when replicating it uses one original strand of n15 and one new strand of n14. When centrifuged, one line, same thickness, slightly higher due to being less dense than just n15 • gen 3 only make new dna out of n14, one n15 strand acts as a template but other strand is n14. when centrifuged, two thin lines, one higher and lower, two dna types, 50% of the dna

• dna strands are antiparallel • dna polymerase is an enzyme with a specific shaped active site which can only bind to substrate with a complimentary shape • can only bind to and add nucleotides to carbon 3 end of developing strand so works in 5 to 3 direction

cancer cells replicate faster

double stranded - both strands act as template for semi-conservative replication weak hydrogen bonds between base pairs - can be unzipped for replication long molecule - store lots of genetic information double helix - compact