Gene Technology Flashcards
(45 cards)
What is DNA sequencing?
Trying to identify base sequence of a new piece of DNA.
How does DNA sequencing work?
- Unknown sequence has a known initial fragment.
- Primer binds, then free and tagged nucleotides bases are added with polymerase enzymes.
- Terminator bases produce fragments of varying lengths.
- Electrophoresis is used to reveal complementary sequence to unknown.
- Laser reads the sequence and provides a complete base sequence.
What is Next Generation DNA sequencing?
- Gel plates in electrophoresis are replaced with flow cells (with millions of DNA fragments attached)
- Chain termination but occurs side by side, producing stacks of DNA
- Laser can then scan multiple stacks
What is Polymerase Chain Reaction (PCR)?
- A form of cloning DNA artificially.
- Makes multiples copies of a tiny sample of DNA.
- Mutiplied = amplified
What are the ingredients of a PCR vial?
- DNA sample
- Free Nucleotides
- Primers (2x)
- Taq DNA polymerase
What is the process of PCR?
- Heat to 95 (hydrogen bonds between nucleotides break)
- Heat to 55 (primers can anneal to original DNA)
- Heat to 72 (Taq polymerase synthesised new DNA complementary to original strand next to primer)
What is the similarity between PCR and DNA replication?
- Both have complementary base pairing.
What are the differences between PCR and DNA replication?
- PCR only replicates a section (100 base pair)
- PCR requires a primer
- DNA double helix is split by helicase in DNA replication but heat in PCR
- Multiple copies are made in PCR
What is DNA profiling used for?
- Produces image of an organisms DNA
- Can identify an individual
- Can work out family relationships and phylogenetic trees
How does DNA profiling work?
- Extract DNA
- Amplify with PCR
- Cut into sections using restriction enzymes
- Can’t cut through mini and microsatellites
What is a mini satellite (variable number tandem repeats)?
- Sequence of 20-50 base pairs which repeat 50-hundred times
- Found in over 1000 locations in a human DNA
What is a micro satellite (short tandem repeats)?
- 2 to 4 bases which repeat 5-15 times
What are exons?
DNA that codes for genes
What are introns?
Non-coding regions (include micro and mini satellites)
Why are micro and mini satellites useful in DNA profiling?
-Location of each type are the same on each person’s chromosomes.
-The sizes varies as they are a mixture of parents chromosomes.
-So, by comparing DNA to parents, you can match all mini and micro to them.
What is the role of PCR in DNA profiling?
Makes lots of copies of the DNA (amplifies).
What is the role of restriction endonucleases in DNA profiling?
Cuts DNA into sections/bands for testing.
How does Gel Electrophoresis work?
-DNA is negatively charged so is attracted to the anode.
- Varying size fragments: bigger travel slower so move less distance across the gel.
What is Gene probe?
- Short sections of single stranded DNA complementary to section we are studying
- fluorescent or radioactive
How can a gene probe be used to detect genetic conditions?
- Take sample of DNA
- Heat to make single stranded
- Mix with gene probe
- If section of DNA (genetic condition) is present, probe will be complementary and so sticks
- Then separate on gel and see if radioactive/fluorescent sections are present.
What is genetic engineering?
The use of technology to change the genetic material of an organism.
How does restriction enzymes identify base sequence?
-Recognises a unique 4-8 base sequence known as its recognition site.
How do restriction enzymes work?
- Attach to DNA
- Search for recognition site
- Bind to site
- Cut the phosphodiester bonds
What is a vector?
An organisms structure that can deliver a gene into a required cell.
