paper 2: Gene Technology Flashcards
define genome
entire set of DNA in anorganism or cell
define proteome
range of proteins that a cell can produce
explain what a genome project is and how it can be used ot determine an organisms proteome
- genome project determins the DNA base sequence of organisms proteome
- this allows the amino acid sequences of the proteins to be determined ( the proteome)
explain why it is easier to determine the denome and proteome of simpler organisms compared to more complex organisms
- easier ot determine prokaryotic DNA as it is shortter and doesnt contain introns that need to be removed by splicing
- whereas more complex organisms the non-coding DNA and regulatory genes mean that the genome cannot be easily translated into the proteome
name one medical use of genome prjects
by identifying the proteome of microoganisms it allows the identification of antigens for the use of vaccine production
define recombinant DNA
DNA made from 2 or more different organsims
explain how complimentary DNA is produced using reverse transcriptase and the advantages of this method
method:
- in beta cells in the human pancreas
- mRNA which codes for insulin is extracted
- the mRNA acts as a template on which a cDNA is formed using reverse transcriptase
- forms single stranded DNA
- then double stranded DNA is formed using DNA polymerase and DNA nucleotides
advantage:
- use mRNA as there are no introns
explain how DNA is cut into fragments and what enzyme is used
- restriction enzymes hydrolyse phosphodiester bonds at recognition sites
- these sequences are palendromic so can be read in oposite directions
- they form sticky ends
explain the advantages of the gene machine method
- faster as no need to isolate DNA/RNA from cell
- any sequence of nucleotides can be made
- no introns so can be expressed by prkaryotes
- vary accurate
define the term vector in therms of making recombinant DNA
vectors carry the gene into the plasmid
explain how a DNA fragment can be inserted into a vector including the improtance of sticky ends
- the plasmid is cut open using the same restriction enzyme as was used to cut out the gene from the DNA
- this is so that the stciky ends on the plasmid are complimentary tot he sticky ends on the gene
- they hydrogen bond
- DNA ligase forms phosphodiester bonds to join the nucleotides of the plasmid and the gene.
- forms recombinant DNA
explain how the DNA of the vector is introduced to host cells by transformation
- the DNA can enter the host cell by using calcium ions, electric shock or heat shock
- makes the membrane more porous
- or using a virus like a bacterophage
explain what a gene marker is and how it can be used to identify which cells have taken up the recombinant DNA/gene
a gene marker identifies which cell has taken up the gene
- antibiotic resistance marker genes grow bacteria on a medium containing the antibiotic the plasmid is resistant to so only the cell containing the plasmids survive
- gene fourescent marker genes glow brighly under UV light
explain why PCR is used
make many copies of a particular DNA base sequence from a small sample
in PCR explain why the DNA has to be heater to 95°
to break the hydrogen bonds between complimentary bases causing the strands to separate
explain in PCR why it is cooled to 55°
to allow primer to bind to the DNA
explain in PCR why it is heated to 72°
it is the optimum temperature for heat stable DNA polymerase
explain in PCR what the primers are for and why 2 are used
primers are used to mark the start and end of the gene that is to be copied
explain how electrophoresis separates DNA and how you can identify unknown lengths of DNA
- DNA fragments are run on an electrophoresis gel
- DNA is negatively charged so moves towards positive electrodes
- shortest fragments move the furthest
- gel is read by lazerbeam and the sequence of colours in converted into DNA sequence
describe what a DNA probe is
a short single strand of DNA that has a complimentary base sequence to the allele and thye bind to the allele and have a radioactive or flourescent label for detection
describe the step-by-step method by which DNA probes can be used to identify the presence of a certain allele by genetic screening
- extract DNA using homogonisation and centrifugation
- use PCR to make many copies of DNA
- cut DNA with restriction enzymes by hydrolysing phosphodiester bonds at recognition sites
- use gel electrophoresis to separate the DNA fragments by lengths
- transfer DNA from gel to nylon mebrane ( southern blotting)
- DNA is made single stranded
- add DNA probe with a complimentary base sequence to the allele with a radioactive/ flourescent label which binds to the alle if present
- wsh the membrane to remove unbound probes and prevent false positives
- identify allele is present using autoradiography
describe the use of genetic counselling
provides individuals with information regarding their probability of developing genetic disorders and probability f passing on genetic disorders to their offspring using genetic screening results.
describe what VNTRs are
repeating DNA bases sequence found between genes.
explain how genetic fingerprinting is acrried out
- extract DNA using homogonisation and centrifugation
- use PCR to make many copies of DNA
- cut DNA ontaininh VNTRs with restriction enzymes by hydrolysing phosphodiester bonds at recognition sites
- use gel electrophoresis to separate the DNA fragments by lengths
- transfer DNA from gel to nylon mebrane ( southern blotting)
- DNA is made single stranded
- add DNA probe with a complimentary base sequence to the VNTRs with a radioactive/ flourescent label which binds to the VNTRs if present
- wsh the membrane to remove unbound probes and prevent false positives
- identify VNTRs is present using autoradiography
explain how the results of genetic fingerprinting are interpreted in a paternity test
all the bands that the child doesn’t mathc the mother must match the father
decribe the uses of genetic fingerprinting in terms of medical diagnosis, forensic science and animal/ plant breeding.
medical diagnosi:
- certain tumours have certain genetic fingerprints which are different formm normla body cells so can be compared to knows types of tumour to diagnose.
forensic science:
-match suspects genetic fingerprint to DNA found at a crime scene e.g. from hair or blood sample
animla and plant breeding:
- can be used to select the least closely related orgnisms, those wo have the most different bands on their gentic fingerprint to prevent inbreeding and reduce chances of gentic disorders
