Chapter 21 Flashcards
Recombinant DNA technology
involves the transfer of DNA from one organism to another. This is possible as the genetic code is universal.
3 ways to produce fragments of DNA
Using mRNA as a template to make complementary DNA via reverse transcriptase
Using restriction endonucleases to cut a fragment containing the desired gene
Creating a gene in the laboratory, using a nucleotide sequence as a template
In vivo DNA amplification
Promoter sequence is added to the DNA where RNA polymerases should start transcribing, and a terminator sequence is added to the end so RNA polymerase stops in the right place during transcription.
Restriction endonucleases are used to cut specific complimentary sticky ends on a DNA fragment and the vector and ligase sticky ends together by forming phosphodiester bonds
Marker genes, such as antibiotic, resistance, or fluorescence, can also be inserted into the vector so the genetically modified host cell can be identified
What is gene therapy
Gene therapy is a technology where are functioning allele is inserted into cells that have one or more faulty copies of that allele. It has the potential to cure disorders that are currently incurable.
Why is gene therapy yet to be successful?
The effect is short lived, an immune response to the vector may occur, the recombinant allele may not be expressed
DNA probe definition
DNA probes are short lengths of single-stranded DNA that has been labelled with either radioactive nucleotides or a fluorescent tag
What is DNA hybridisation
The binding of the probe to the complimentary single strands of DNA
Why is hybridisation useful?
The presence or location of the probe can be identified
An example of in vitro cloning
PCR
What is four things are needed for PCR
Target DNA, thermostable DNA polymerase, the four base nucleotides, primers
What are primers?
Short pieces of DNA that acts as signals to DNA polymerase to start replication
Steps of PCR
Strand separation - the target DNA is heated to 95°C for five minutes to separate the two strands
Primer binding - the mixture is rapidly called to 55°C so primers can combine to complimentary sites on the target DNA
Strand synthesis - the mixture is heated to 72°C and the thermostable DNA polymerase copies both strands of the target DNA
The process is then repeated
Three uses of genetic fingerprinting
Forensics science, medical diagnosis, animal and plant breeding
5 steps of genetic fingerprinting
Extraction, digestion, separation, hybridisation, development
How does gel electrophoresis work?
Because DNA has a negative charge smaller fragments move further through the gel than larger fragments
