Biotechnology Flashcards
Define Gel Electrophoresis
A technique used to seperate DNA fragments according to size, used in DNA profiling to give a unique pattern/sequence
Define Polymerase Chain Reaction
A technique used to amplify small quantities of DNA of a specific DNA region
What is Restriction Enzyme Digestion?
Cuts the DNA at specific sequence / site
What is Profiling?
Provides a unique pattern of bands from a DNA sample , used to compare samples
What is DNA sequencing?
DNA sequencing is the process of determining the sequence of nucleotides e.g. AATTT
What is DNA extraction?
Process by which DNA is removed from the nucleus and from the cells
What are recognition sites?
An enzyme will always cut the DNA at a point where there is a specific sequence of bases
What does DNA ligase do?
An enzyme found in E.coli bacteria that is used to ‘glue’ together short strands of DNA during replication
What are plasmids?
Small circular strand of DNA distinct from the main bacterial genome, it is composed of only a few genes and is able to replicate independently within a cell
What does ‘Ligase’ refer to?
An enzyme capable of combining two small components of single strand DNA into one single structure
What are the steps in Polymerase Chain Reaction?
- DNA is denatured at 94-96 degrees, a double strand is separated into 2 single strands
- Annealing primers activate between 50-60 degrees, temperature drops slightly and then primers attach/anneal and bind to each strand and their complementary bases, a new DNA is then synthesised
- At 72 degrees Taq polymerase attaches to the primer and extends/syntheses the new DNA strand
What is the application of PCR?
- Detecting hereditary diseases
- Detection of viral diseases
- Forensic science - when needing to amplify small amounts of blood, semen, hair etc
Explain the process of Gel Electrophoresis
- Make the gel
- Add comb to the gel and allow it to set
- Add dye to the DNA sample
- Place agarose gel into the tank - electrophoresis
- The buffer (liquid) is added to cover the gel
- DNA sample is loaded into the wells of the gel
- An electric current is applied
- DNA is negatively charged and therefore the DNA fragments move from the negative end to the positive end as the DNA is attracted to the positive end
- Smaller DNA segments move faster and farther than larger DNA fragments
- Gel is stained with DNA binding dye for a few minutes
- Gel is placed under UV light and the sequence will fluoresce, showing the band sequence
Explain the process of DNA sequencing
- The mixture is first heated to denature the template DNA (separate the strands)
- The temperature is then lowered slightly so that the primer can attach/enter
- Temperature is then slightly raised and the enzyme binds to the DNA and elongation occurs
- DNA will elongate until a dideoxynucelotide binds then the sequence wills top as no more can bind as the dideoxynucelotide lacks OH, this results in the collection of DNA strands in different sizes and lengths
- The DNA then goes through a polyacymide gel which s more porous in a DNA sequencer
- The DNA sequencer then analyses the gel and the fragments migrate according to size and each is detected as it passes through a laser beam light, each dideoxynucelotide emits a different colour and is recorded as a colour band on a stimulated gel image which gives us the exact DNA sequence
What are gene probes?
Single stranded DNA labelled with a fluorescent marker to detect the presence of specific DNA sequences on another DNA or RNA molecule. It can be sued to detect hereditary diseases such as cystic fibrous or Huntington’s disease. To detect the disease the probe is made to specifically bind to the specific DNA sequence of the disease