gene technology Flashcards
recombinant DNA
DNA from one organism which has foreign DNA inserted into it
transgenic organism
an organism which contains a foreign gene in its DNA
why is ‘recombining’ DNA by transferring DNA of one organism into another possible?
-DNA code universal
-transcription and translation are very similar in most organisms
-creates a transgenic organism
obtaining DNA fragments by using reverse transcriptase:
converts mRNA back into DNA, reverses transcription mRNA is taken from cells which produce a lot of the protein DNA codes for and mixed with DNA nucleotides and reverse transcriptase enzymes to synthesise a new DNA strand.
the cDNA produced contains no introns
obtaining DNA fragments by using restriction endonuclease enzymes:
-each restriction endonuclease recognises a specific DNA base sequence. Base sequences are palindromic. Enzymes active site has a specific shape which is complementary to shape of specific DNA base sequence. Can leave both sticky or blunt ends
Palindromic meaning
can be read both ways within double strand
Why are sticky ends more useful?
unpaired bases at each end of the fragment to allow them to bind with another DNA fragment with sticky ends with a complementary sequence.
obtaining DNA fragments Using a gene machine.
Design base sequence. Add nucleotides to a support to fix in place. Add other nucleotides in the correct order - the protecting group (blocking agent here) makes sure they attach at the right places. Short sections of DNA (oligonucleotides) are produced and once the protecting groups are removed these can join together to make larger pieces of DNA.
DNA polymerase-
enzyme which joins DNA nucleotides together to form sugar phosphate backbone of a new DNA strand.
primers
short sequence of nucleotides which are complementary to those at the end of the DNA to be copied
nucleotides
which contain each of the four bases found in DNA- build new strand from
thermocycler
a computer controlled machine that varies temperature over a period of time
similarities between PCR and DNA replication
-breaking H bonds to form strands
-both use DNA polymerase
-both add free nucleotides for new strand
-both produce double stranded DNA
differences between PCR and DNA replication
-DNA replicaton doesn’t require heat whereas PCR does
-PCR requires primers, DNA rep doesn’t
Polymerase Chain Reaction - Model Answer
-Heat the sample to 95C to break H bonds and separate bonds.
-Add primers and cool to 55 to allow primers to bind to complementary strands
-Increase the temperature to 72 and add thermostable DNA polymerase and free DNA nucleotides
-Nucleotides bind to the primer
-DNA polymerase will copy the strands
