dna and rna

functions of chromatin

• package and condense dna

• prevent dna damage

• control dna expression

what are nucelosomes

• ‘beads on a string’

• around 146 base pairs of dna wrapped around 1.7 times around a core

• core is comprised of an octamer of histone proteins

• nucleosome core proteins are separated by linker proteins

• histone H1 brings nucelosomes together to condense chromatin further

• multiple stacked rings form the solenoid fibre/30nm fibres

• these are coiled further to form chromosomes

pcr

• heat to 94 to denature (separate) dna strands

• cool to 50-60 to allow primers to anneal

• 72 to allow elongation of new strands using taq polymerase

• so at the end of the first cycle 2 new strands

• begin cycle two by denaturing and annealing again

• elongation generates strands of different sizes depending on the template strands

sanger sequencing

• mix small amount dideoxy with deoxy nucleotides

• cycle through multiple rounds of pcr

• each ddNTP contains fluorescent tags

• separate by gel electrophoresis

• detect by laser

• (chain synthesis terminates when ddNTP is incorporated)

technical applications of PCR that could be used to an advantage in veterinary medicine

• VNTR

• RAPD

• AFLP

• they are all used to determine breed, pedigree and/or parentage

what components are essential for basic PCR?

• DNA polymerase

• all 4 deoxyribonucleotides

• dsDNA template

• a pair of primers which bind to opposite polynucleotide strands and have their 3 ends pointing towards each other