21.1 Producing DNA fragments Flashcards
What (3) ways are there to obtain DNA fragments?
- reverse transcriptase
- restriction endonuclease
- gene machine
main points for using reverse transcriptase to get DNA fragments
- mRNA from cells
- use reverse transcriptase to form cDNA
- cDNA isolated by DNA helicase
- DNA polymerase forms another strand
- gene made
where is the mRNA taken from?
cells that produce the desired protein
what is cDNA?
complementary strand to the mRNA
how is the second strand formed?
from free nucleotides joined by condensation reaction of the DNA polymerase
how is the cDNA used?
used as a template strand
main points for using restriction endonuclease to obtain DNA fragments
- RE recognises recognition site/restriction site
- cuts at cleavage site
= produces sticky ends
what are restriction endonuclease enzymes?
enzymes that cut DNA at a specific base sequence
what is the restriction site?
specific sequence of bases that RE recognise
what is the cleavage site?
the site the RE cuts at
how are sticky ends useful? why?
allow the binding of DNA from one organism to another as long as the same RE used
- contain complimentary base pairs
what are sticky ends?
- staggered pieces of DNA that are complimentary to each other
- produced when RE cuts at cleavage site
main points for using the gene machine to obtain DNA fragments
- desired protein turned into a/a sequence
- a/a sequence turned into mRNA
- turned into a DNA sequence
- use oligonucleotides to form gene
- use PCR to replicate gene
- insert into plasmid
what is the DNA made from gene machines checked for?
- biosafety
- biosecurity
- ethics
what are oligonucleotides?
- single strands of oligonucleotides
- overlap
- short
