8b genome projects and gene technologies Flashcards
what is a genome ?
Entire set of DNA including all the genes in an organism
What are gene sequencing methods?
They work on fragments of DNA which are smaller pieces that are sequenced and put in order to give the whole genome
Why do you want to identify the proteome of DNA?
Useful in identifying medical research and development eg identifying protein antigens on the surface of disease causing bacteria
why do complex organisms contain regulatory genes?
determine when the genes that code for particular proteins should be switched on and off
why do regulatory genes make it harder to translate the genome?
It is harder to translate the genome into the proteome because it is hard to find the bits that code for proteins among non coding and regulatory DNA
What is recombinant DNA technology?
transferring a fragment of DNA from one organism to another
what does the transfer of Dna produce?
a protein in the cells of the recipient of the organism
what is transgenic organisms?
organisms that contain transferred DNA
what are the three ways of producing dna fragments?
method 1 - using reverse transcriptase
method 2- using restriction endonuclease enzymes
method 3 - using a gene machine
How can you use reverse transcriptase ?
- mrna is first isolated from cells
- mixed with free DNA nucleotides and reverse transcriptase
- Reverse transcriptase uses mRNA as a template to synthesis new strands of complementaryDNA
What is palindromic sequences?
Consists of antiparallel base pairs that read the same in opposite directions
what is restriction endonucleases?
enzymes that recognise specific palindromic sequences and cut DNA at places
Why do different restriction endonucleases cut at different specific recognition sequences?
The shape of the recognition sequence is complementary to enzymes active site
What’s the procedure if recognition sequences are present either side of DNA fragment?
- Use restriction endonucleases to separate from rest of DNA
- incubated with specific restriction endonucleases cutting DNA fragment out via hydrolysis
- Cut leaves stickey ends - tails of unpaired bases at each end of fragment
- Binds dna fragment to another piece of dna that has sticky ends with complemtary sequences
How can you use a gene machine?
- the sequence that is required is designed
- First sequence in nucleotide is fixed to some support
- Nucleotides are added step by step in a cycle of processes that include protecting groups
- Oligonucleotides are broekn off from support and protecting groups removed
- Oligonucleotides are joined to make longer DNA fragments.
What is a protecting group?
Make sure nucleotides are joined at the right points to prevent unwanted branching
what is in vivo cloning?
where gene copies are made within a living organism so the dna can be replicated
what is in vitro cloning?
gene copies are made outside of a living organism using polymerase chain reaction
How does part 1 of in vivo cloning work? - recombinant DNA
- Insert DNA fragment into a vectors DNA
- Vector DNA is isolated and restriction endonucleases and DNA ligase are used to stick their dna fragment and vector
- Vector DNA is isolated
- Vector DNA cut open using restriction endonucleases that was used to isolate target gene
- sticky ends of vector complementary to DNA fragment
- Vector DNA and fragment mixed with ligase joining the sticy end of fragment to sticky end of vestor dna - LIGATION
- new combo of bases in DNA
What is part 2 of in vivo cloning? - transforming cells
- Vector cells with recombinant DNA is used to transfer gene into cells
- The host cells take up the vectors containing gene which are then transformed
- A bacteriophage vector will infect host bacterium by injecting its DNA
- The phage DNA integrates into bacterial DNA
What is part 3 - identifying transformed cells?
- Marker genes are inserted into vectors at the same time as the gene to be cloned
- Any transformed host cells will contain the gene to be clones and the marker gene
- Host cells are grown on agr plates and each cell divides replicating dna
- Transformed cells will produce colonies where all cells contain cloned gene and marker
- Marker gene codes for antibiotic resistance
- Only transformed gene with marker will survive and grow
- A marker gene will also calls transformed cells to fluoresce
- Identified transformed cells are allowed to grow more producing lots of copies of the cloned gene
How can you get the transformed host cell to produce proteins?
Make sure that the vector contains specific promotor and
terminator regions
What is in vitro cloning?
Copies of the DNA fragments are made outside organism using a PCR
What is the first step on in vitro cloning?
A reaction mixture containing DNA sample, free nucleotides, primers and dna polymerase is set up