1
Q
How is gel electrophoresis carried out? 18
A
- Pour agarose gel into gel tray
- Leave to solidify
- Row of wells is created at one end of gel
- Put gel tray in gel box
- End of gel tray with wells - closest to cathode
- Add buffer solution to resevoirs at side of gel box - surface of gel covered in buffer solution
- Use micropipette to add loading dye to each fragmented DNA sample
- Add set volume of DNA sample to first well without piercing bottom of it
- Record which DNA sample added to which well
- Put lid on gel box and connect to power supply
- Turn on and set to required voltage allowing current to pass through gel
- Let gel run for 30 minutes/until DNA 2cm from end
- Turn off power supply
- Remove gel tray from gel box
- Tip off excess buffer solution
- Cover gel in staining solution: staining DNA fragments
- Rinse gel with water
- Bands of different DNA fragments separated according to length now visible
2
Q
Why add loading dye to fragmented DNA samples?
A
Helps DNA sample sink to bottom of well and become easier to see
3
Q
Explain how to carry out effect of antibiotics on bacterial growth 10
A
- Use wire inoculation loop to transfer bacteria to agar plate
- Spread bacteria over the whole plate
- Place paper disks soaked with different antibiotics spaced apart on plate
- Use negative control soaked only in sterile water
- Tap lid onto Petri dish
- Incubate
- Invert
- At 25 degrees for 24-48 hours
- Inhibition zones are where bacteria doesn’t grow : measure the size
- Larger the zone, the more powerful the antibiotic
4
Q
What aspetic techniques should be observed when using bacteria? 3
A
- Regularly disinfecting surfaces
- Working next to Bunsen Burner flame so hot air rises and other microbes in the air are drawn away from culture
- Sterilising inoculation loop before and after each use for 5 minutes in Bunsen Flame
- Close windows and doors
- Sterlise all glassware before and after use in autoclave
5
Q
What are the two purposes of aseptic techniques?
A
- Stops contamination of bacteria culture investigated
- Stops direct contact with pathogens that could cause infection
Bio: CORE PRACTICALS
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