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
step 1 of the polymerase chain reaction
reaction mixture is set up containing DNA sample, free nucleotides, primers and DNA polymerase
step 2 of the polymerase chain reaction
DNA mixture is heated to 95 degrees to break H bonds then cooled to 50-65 for the primers to anneal
step 3 of the polymerase chain reaction
mixture heated to 72 and so DNA polymerase can work to create a new complementary strand
step 4 of the polymerase chain reaction
two new copies of the fragment formed and the cycle starts again
every cycle of the PCR produces..
two times more of the fragment
transformed plants can be produced by…
a gene that codes for a desirable protein is inserted into a plasmid
transformed animals can be produced by…
a gene that codes for a desirable protein can be inserted into an embryo or egg
what are the benefits of transformed organisms in agriculture?
can be transformed to give higher yields, be more nutritious and have resistance to pests
what are the benefits of transformed organisms in industry?
industrial processes that use enzymes are produced from transformed organisms
what are the benefits of transformed organisms in medicine?
make production cheaper and quicker
what are the concerns of transformed organisms in agriculture?
- organic crops could be contaminated from nearby modified crops
- the crop could all be vunerable to the same disease
what are the concerns of transformed organisms in industry?
without proper labelling some people think they won’t have a choice of eating it
what are the concerns of transformed organisms in medicine?
companies who known genetic engineering technologies may limit used of technologies that could be saving lives
gene therapy is…
altering the defective genes inside cells to treat genetic disorders and cancer
the two types of gene therapy are…
somatic therapy
germ line therapy
somatic therapy is…
altering the alleles in the body cells, particularly the cells that are most affected by the disorder. this doesn’t affect the persons sex cells
germ line therapy involves…
altering the alleles in sex cells
does somatic or germ line therapy stop the offspring from inheriting a disease?
germ line
gene probes can be used to…
locate specific alleles of genes or to see if a person’s DNA contains a mutated allele that causes a gentic disorder
what are DNA probes?
short strands of DNA that have a specific complementary base sequence of the target allele
DNA probes have what attached?
a radiocative or fluorescent label
step 1 of locating alleles using DNA probes
a sample of DNA is digested into fragments using restriction enzymes and seperated using electrophoresis
step 2 of locating alleles using DNA probes
the seperated DNA fragments are transferred to a nylon membrane and incubated with a fluorescent DNA probe. if present it will bind to it
step 3 of locating alleles using DNA probes
the membrane is exposed to UV and if gene is present there will be a fluorescent band
the uses of screening with DNA probes are….
- used to identify inherited conditions
- can be used to help determine how a patient will respond to certain drugs
- can be used to identify health risks
genetic counselling is…
advising patients and their relatives about the risks of genetic disorders. can show them options of prevention or treatment
personalised medicine is…
medicine that is tailored to an individual’s DNA
what are the steps to making a genetic fingerprint?
- PCR is used to make DNA fragments
- seperation of the DNA fragments by gel elctrophoresis
- analysis of genetic fingerprints
what are the uses of genetic fingerprinting?
- determining genetic relationships
- determining genetic variablity within the population
- in forensic science
- for medical diagnosis
- in plant and animal breeding
