Topic 6 Flashcards

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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
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2
Q

Why add loading dye to fragmented DNA samples?

A

Helps DNA sample sink to bottom of well and become easier to see

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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
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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
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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

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