genetic technology Flashcards
What does the genetic code is universal mean?
that almost every organism uses the same four nitrogenous bases – A, T, C & G.
There are a few exceptions
This means that the same codons code for the same amino acids in all living things (meaning that genetic information is transferable between species)
Thus scientists have been able to artificially change an organism’s DNA by combining lengths of nucleotides from different sources (typically the nucleotides are from different species)
define recombinant DNA (rDNA)
The altered DNA, with the introduced nucleotides
transgenic organism
If an organism contains nucleotide sequences from a different species
genetically modified organism (GMO)
Any organism that has introduced genetic material
genetically modified organism (GMO)
Any organism that has introduced genetic material
What is genetic engineering?
is a technique used to deliberately modify a specific characteristic (or characteristics) of an organism.
What does the genetic engineering technique involve?
removing a gene (or genes) with the desired characteristic from one organism and transferring the gene (using a vector) into another organism where the desired gene is then expressed
What will the genetically engineered organism contain?
recombinant DNA and will be a genetically modified organism (GMO)
What are the following steps In order for an organism to be genetically engineered ?
Identification of the desired gene
Isolation of the desired gene by:
- Cutting from a chromosome using enzymes (restriction endonucleases)
- Using reverse transcriptase to make a single strand of complementary DNA (cDNA) from mRNA
- Creating the gene artificially using nucleotides
- Multiplication of the gene (using polymerase chain reaction - PCR)
- Transfer into the organism using a vector (e.g. plasmids, viruses, liposomes)
- Identification of the cells with the new gene (by using a marker), which is then cloned
What do genetic engineers need to modify and organism?
Enzymes (restriction endonucleases, ligase and reverse transcriptase)
Vectors - used to deliver genes into a cell (eg. plasmids, viruses and liposomes)
Markers - genes that code for identifiable substances that can be tracked (eg. GFP - green fluorescent protein which fluoresces under UV light or GUS - β-glucuronidase enzyme which transforms colourless or non-fluorescent substrates into products that are coloured or fluorescent)
synthetic biology
- genetic engineering is being used
This is an area of research that studies the design and construction of different biological pathways, organisms and devices, as well as the redesigning of existing natural biological systems
synthetic biology
- genetic engineering is being used
This is an area of research that studies the design and construction of different biological pathways, organisms and devices, as well as the redesigning of existing natural biological systems
The gene with the specific characteristic that is required can be obtained in the following ways:
Extracting the gene from the DNA of a donor organism using enzymes (restriction endonucleases)
Using reverse transcriptase to synthesise a single strand of complementary DNA (cDNA) from the mRNA of a donor organism
Synthesising the gene artificially using nucleotides
The extraction of the gene (containing the desired nucleotide sequence) from the donor organism. How does this occur?
using restiction endonucleases.
Restiction endonucleases/enzyme
The enzymes restrict a viral infection by cutting the viral genetic material into smaller pieces at specific nucleotide sequences within the molecule.
- many diff as bind to specific restiction site on DNA
- will seprarate 2 stands of DNA at specific base sequences by ‘cutting’ the sugar-phosphate backbone in an uneven way to give sticky ends or straight across to give blunt ends
what do sticky ends result in?
one strand of the DNA fragment being longer than the other strand
The sticky ends make it easier to insert the desired gene into another organism’s DNA as they can easily form hydrogen bonds with the complementary base sequences on other pieces of DNA that have been cut with the same restriction enzyme
blunt ends
Blunt ends are fragment ends of a DNA molecule that are fully base paired.
When using genes isolated by restriction endonucleases that give blunt ends nucleotides can be added to create sticky ends
Another method to isolate the desired gene is to use the mRNA that was transcribed for that gene
Once isolated, the mRNA is then combined with a reverse transcriptase enzyme and nucleotides to create a single strand of complementary DNA (cDNA)
The mRNA is used as a template to make the cDNA
DNA polymerase is then used to convert the single strand of cDNA into a double-stranded DNA molecule which contains the desired code for the gene
method to isolate the desired gene is to use the mRNA that was transcribed for that gene. Why is it considered advantageous?
it is easier for scientists to find the gene because specialised cells will make very specific types of mRNA (eg. β-cells of the pancreas produce many insulin mRNAs) and the mRNA (therefore the cDNA) does not contain introns
method to isolate the desired gene is to use the mRNA that was transcribed for that gene. Why is it considered advantageous?
it is easier for scientists to find the gene because specialised cells will make very specific types of mRNA (eg. β-cells of the pancreas produce many insulin mRNAs) and the mRNA (therefore the cDNA) does not contain introns
As scientists are becoming more familiar with the base sequences for our proteins (proteome) what is becoming possible?
the synthesis of genes artificially.
- With the knowledge of the genetic code (that is, which amino acids are required) scientists use computers to generate the nucleotide sequence (rather than an mRNA template) to produce the gene
- Short fragments of DNA are first produced which are joined to make longer sequences of nucleotides and then inserted into vectors (eg. plasmids)
- This method is being used to create novel genes being used to make vaccines and even to synthesise new bacteria genomes
In order to genetically engineer an organism there are a number of enzymes required what are they?
Restriction endonuclease
Revese transcriptase
DNA polymerase
DNA ligase
role of Restriction endonuclease in the transfer of a gene into an organism
Isolate the desired gene
Separate the DNA strands (at the same base sequence) in a vector so the desired gene can be inserted
cuts the DNA strands so that the desired gene can be isolated or spliced (inserted) into a vector
will separate the two strands of DNA at the specific base sequence by ‘cutting’ the sugar-phosphate backbone in an uneven way to give sticky ends or straight across to give blunt ends
Sticky ends result in one strand of the DNA fragment being longer than the other strand
The sticky ends make it easier to insert the desired gene into another organism’s DNA or into a vector as they can easily form hydrogen bonds with the complementary base sequences on other pieces of DNA that have been cut with the same restriction endonucleases
the role of reverse transcriptase in the transfer of a gene into an organism
produce a single-strand complementary DNA
molecule (cDNA) that contains the code for the
desired characteristic
- this will then be inserted into a vector (after being
converted into a double-stranded DNA molecule