Introduction to Molecular Techniques Flashcards
What techniques are involved in analysis of DNA at the gene level?
Restriction enzymes, DNA gel electrophoresis and PCR
Also southern hybridisation, microarray, PCR variations
What techniques are involved in analysis of protein?
Protein electrophoresis, immunoassays and enzyme assays
What technique is involved in analysis of DNA at the nucleotide level?
DNA sequencing
What techniques are involved in analysis of DNA at the chromosome level?
Karyotyping and FISH
What are restriction enzymes?
Enzymes that cut a DNA molecule at a particular place
What bonds do restriction enzymes cut?
Phosphodiester
What do restriction enzymes recognise and cut?
Specific DNA sequences (restriction sites) - mostly palindromic
What restriction site does EcoRI recognise?
GAATTC
What does EcoRI digestion produce?
Sticky ends (complementary base pairs)
How does DNA gel electrophoresis separate DNA fragments?
Based on their size - DNA is negatively charged due to the phosphate groups so they will move towards the positive electrode. Smaller fragments move further.
What are the requirements for gel electrophoresis?
- Gel - matrix allowing separation of fragments
- Buffer - allows charge on the DNA samples across gel
- Power supply - generate charge difference
- Stain/detection - identify presence of separated DNA (fluorescent markers)
Why would we use restriction analysis?
- To investigate size of DNA fragments to see if there are any changes in DNA (eg small deletions)
- To investigate mutations (eg sickle cell disease)
- To investigate DNA variation (DNA fingerprinting)
- To clone DNA
What are the four basic steps of gene cloning?
- Isolate relevant gene following digestion with restriction enzymes
- Insert gene of interest into plasmid vector (recombinant DNA molecule)
- Introduce recombinant DNA molecule into suitable host cells (eg Ecoli)
- Identidy and isolate the clone containing the DNA of interest
Why would we clone human genes?
To make useful proteins eg insulin
To find out what genes do eg HTT
Genetic screening eg Huntingtons
Gene therapy
What does reverse transcriptase do?
Converts RNA to cDNA
What is the enzyme used in the Polymerase Chain Reaction?
Taq polymerase
What does PCR require?
Taq polymerase
Primers
Nucleotides
Why is taq polymerase used in PCR/
It is thermostable
What is the purpose of PCR?
To amplify DNA
What are the basic steps of PCR?
- At temp of 90 degrees, DNA denatures and hydrogen bonds are broken
- At temp of 60 degrees, primers anneal
- At temp of 72 degrees, TAQ polymerase adds nucleotides to complementary strands