3.5 Flashcards
what is PCR
polymerase chain reaction, to make multiple copies of a specific segment of DNA
uses of PCR
- analysis of forensic material
- paternity testing
- DNA barcoding
- analysis of historic material
- genetic counselling
- build phylogenic trees
role of template DNA (in PCR)
segment that we want to copy
role of primers (in PCR)
short DNA fragments needed to select the specific sequence to be amplified and to initiate replication
role of taq polymerase (in PCR)
heat resistant enzyme that catalyses DNA replication
role of buffer (in PCR)
provide stable conditions for reactions
describe the 3 steps of PCR
DENATURING
- 94-96 °
- hydrogen bonds between chains break
- separate into 2 strands
PRIMER ANNEALING
- 50-65 °
- allows primers to anneal (attach) to each 3’ end of each strand
ELONGATION
- 72°
- heat tolerant taq polymerase replicate the region of DNA
what is gel electrophoresis used for
separation of DNA fragments by size
steps for gel electrophoresis
- samples placed in a well in agarose gel
- electric field applied
- DNA being negatively charged migrates to positive pole
- the gel is porous so smaller fragments move faster
- DNA is stained with ethidium bromide and smaller molecules will be more advanced than bigger ones
what is restriction endonuclease used for
molecular scissors to cut up the genome of bacteriophages
what are bacterial plasmids
short, circular pieces of DNA that may occur in a bacterium. they carry advantageous genes
what is DNA ligase
enzyme that can mend the DNA backbone, used to paste DNA into a plasmid
what is reverse transcriptase
an enzyme that reverse transcribes mRNA into DNA, the resulting DNA is called cDNA
what is genetic modification
the transfer of genes from one organism to another
