Genome Projects and Gene Technologies (Topic 8B) Flashcards
Scientists used a radioactively labelled DNA probe to show that the cells of tobacco plant leaves contained the SUT1 gene. Describe how they would do this
4 marks
- extract DNA and add restriction endonucleases
- separate fragments using electrophoresis
- treat DNA to form single strands
- the probe will bind to the SUT1 gene
define genome
the entire set of DNA including all the genes in an organism
what do scientists do in genome projects?
determine the complete genome sequence of an organism
define proteome
all of the proteins that are made by an organism
why can a simple organisms proteome from the DNA sequence of their genome be determined easily?
they don’t have much non-coding DNA
why is it more difficult to determine the proteome of a complex organism than a simple organism?
complex organisms contain more non-coding DNA so it’s hard to distinguish between the non coding and the regulatory DNA
what are the 3 methods for making DNA fragments?
- using reverse transcriptase
- using restriction endonuclease enzymes
- using a gene machine
how does reverse transcriptase produce DNA fragments?
mRNA is isolated from cells. Then it’s mixed with free DNA nucleotides and reverse transcriptase.The reverse transcriptase uses the mRNA as a template to synthesise new strands of cDNA.
what is a palindromic sequence of nucleotides?
nucleotide sequences that consist of antiparallel base pairs that read the opposite in the same direction
how do restriction endonucleases produce DNA fragments?
if recognition sequences are present at either side of the DNA fragment restriction endonucleases to seperate it from the rest of the DNA. it leaves the fragment with sticky ends that anneal the DNA fragment to another piece of DNA with complementary sticky ends
what is cDNA?
complemetary DNA
how does the gene machine produce DNA fragments?
- the sequence that is required is designed
- the first nulceotide sequence is fixed to a bead
- nucleotides are added one by one in the correct order and protecting groups are added
- oligonucleotides are produced and once complete are broken off from the support and protecting groups are removed. the oligonucleotides are joined to make longer DNA
oligonucleotides are….
short section of DNA that are roughly 20 nucleotides
in vivo cloning is…
where gene copies are made within a living organism
in vitro cloning is…
where gene copies are made outside of a living organism using the PCR
what are the 3 parts to in vivo cloning?
- making recombinant DNA
- transforming cells
- identifying transformed cells
how is recombinant DNA made in in vivo cloning?
- the vector DNA is isolated
- the vector DNA is cut opeusing the same restriction endonuclease used to isolate the DNA fragment
- DNA ligase joins sticky ends of DNA fragment to the vector DNA
- the new combination of bases in the DNA is called recombinant DNA
how are cells transformed in in vivo cloning?
the vector with the recombinant DNA is used to transfer the gene into host cells
how are identified cells transformed in in vivo cloning?
- marker genes are inserted into the gene when its cloned
- the marker gene can code for antibiotic resistance therfore when transferred onto agar bacteria will not grow where it is present
- indentified transformed cells are allowed to frow more, producing more copies