21 recombinant DNA technology Flashcards
define genome
the complete set of genes in a cell of an organism
what is happening to the way we sequence genomes?
constantly improving and advancing
has now become automated
which organism has DNA that doesn’t contain introns?
prokaryotic cells
define proteome
full set of proteins the genes of an organism can code for
why can’t the genome easily be used to translate the proteome in a human, but in bacteria it can?
human DNA has introns
bacterial DNA has no introns
why is it useful to be able to translate the genome of bacteria to its proteome?
identifying potential antigens to use in a vaccine
what does recombinant DNA mean?
a cell having 2 or more sources of DNA
how can recombinant DNA be achieved?
by isolating the fragments of DNA and inserting into another organism
what are 5 steps in recombinant DNA technology?
- isolation of genes
- insertion
- transformation
- identification
- cloning
what are 3 ways to isolate a copy of a specific DNA fragment?
- reverse transcriptase
- restriction enzymes
- gene machine
how would reverse transcriptase isolate a copy of a specific gene?
1.free DNA nucleotides bind to single stranded mRNA (complementary base pair)
2. reverse transcriptase joins DNA nucleotides together to form single stranded cDNA
3. DNA polymerase makes cDNA double stranded
give 3 advantages of using reverse transcriptase as a way of isolation
- cDNA intron free
- mRNA much easier to obtain
- mRNA can be isolated from the cytoplasm of cells which produce the protein in large amounts
what are the restriction enzymes called?
restriction endonucleases
how would restriction enzymes isolate a copy of a specific gene?
- restriction endonuclease hydrolyse DNA at specific recognition sequence
- recognition sequence palindromic
- cut is either blunt or sticky
- blunt ends have no overhang so cannot reanneal
- sticky ends have overhang so do reanneal
how would the gene machine isolate a copy of a specific gene?
- desired sequence fed into computer
- synthesis of oligonucleotides
- oligonucleotides joined together and made double stranded by PCR
what are oligonucleotides?
short sequences of nucleotides
what is an advantage for using the gene machine?
artificial genes are easily transcribed and translated by prokaryotes as they have no introns
how do you insert genes into plasmid?
through vectors
define vector
DNA carrier used to transfer foreign DNA into cells
how do you insert DNA into a vector?
- cut open vector with same restriction endonuclease
- complementary sticky ends
- DNA ligase anneals DNA fragment to vector DNA (ligation)
what bond does ligation form?
phosphodiester bond
explain transformation
- DNA vector transferred into bacteria
- host cells referred to as recombinant or transformed organism
explain how you can identify transformed host cells
add marker genes onto the cells and only transformed host cells will synthesise desired protein