Topic 8- Recombinant DNA Flashcards
What is the function of the genetic code?
Stores instructions (alongside environmental influences), that dictate the behaviour of cells and as a result, the behaviour of the whole organism
Why is it important that the genetic code is universal?
The same codons code for the same amino acids in all living things -meaning that genetic information is transferable between species
What is recombinant DNA (rDNA)?
artificially changing an organism’s DNA by combining lengths of nucleotides from different sources (typically the nucleotides are from other species)
What is a transgenic organism?
an organism contains nucleotide sequences from a different species, it is genetically modified
Which mechanisms are universal meaning that the transferred DNA can be translated within cells of the genetically modified organism?
Transcription and translation
What must happen for an organism to be genetically modified?
-Identification of the DNA fragment or gene
-Isolation of the desired DNA fragment
-Multiplication of the DNA fragment (using polymerase chain reaction - PCR)
-Transfer into the organism using a vector (e.g. plasmids, viruses, liposomes)
-Identification of the cells with the new DNA fragment (by using a marker), which is then cloned
What 3 things are needed for an organism to be modified?
-Enzymes (restriction endonucleases, ligase and reverse transcriptase)
-Vectors - used to deliver DNA fragments into a cell (eg. plasmids, viruses and liposomes)
-Markers - genes that code for identifiable substances that can be tracked
What field of genetic engineering is this being used for?
synthetic biology-studies the design and construction of different biological pathways, organisms and devices, as well as the redesigning of existing natural biological systems
What is genetic engineering?
the deliberate modification of a specific characteristic (or characteristics) of an organism
What does genetic engineering involve?
emoving 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
How are DNA fragments/specific genes isolated?
-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 in a “gene machine”
How can you use mRNA and reverse transcriptase to isolate a gene?
- use the mRNA that was transcribed for that gene
-mRNA is extracted by cell fracination and ultracentrifugation
-mRNA is then combined with a reverse transcriptase enzyme and nucleotides to create a single strand of complementary DNA (cDNA) (mRNA is used as a template strand)
-DNA polymerase and free DNA nucleotides
are used to convert the single strand of cDNA into a double-stranded DNA which contains no introns
What is the function of reverse transcriptase?
catalyse the reaction that reverses transcription
What is the advantage of using mRNA and reverse transcriptase?
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
Give some examples of where gene technology is used.
-GM crops (produce a higher yeild, resistance to certain diseases/other factors impacting growth)
-Gene therapy (useful for genetic conditions)
-Genetic fingerprinting
What are the two ways genes are cloned?
-In vivo- inserting specific gene fragments into vectors
-in vitro- the polymerase chain reaction (PCR), DNA segments are quickly and efficiently amplified many times
What is reverse transcriptase?
-An enzyme that is produced by retroviruses
How do retroviruses use reverse transcriptase?
-Convert their viral RNA genome template into DNA
-This DNA can then be integrated into the host DNA
