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When isolating DNA from a plant tissue, how many steps are there?
- 10 steps.
- 1. Add washing-up liquid and salt to graduated cylinder
- 2. Add chopped onions and salty washing-up liquid solution to a beaker.
- 3. Beaker in water bath at 60*
- 4. Cool mixture by ice bath
- 5. Blend
- 6. Filter blended mixture
- 7. Add protease enzyme into onion extract.
- 8. Pour ice cold ethanol onto surface of onion extract
- 9. DNA forms at interface of the ethanol and onion extract.
- 10. Draw DNA out with glass rod
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When isolating DNA from a plant tissue, why is washing-up liquid used?
Breaks up cell membranes by causing lipids and proteins to break apart.
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When isolating DNA from a plant tissue, why is salt used?
Salt stops the DNA from being attracted to cell membranes- would be difficult then to isolate DNA.
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When isolating DNA from a plant tissue, what temperature is the warm water bath put at and why?
Beaker sits in water bath at 60* (denatures enzymes- that would digest DNA)
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When isolating DNA from a plant tissue, how is the mixture cooled and why?
- In an ice bath for 5 min
- Helps prevent the breakdown of DNA by high temperature.
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When isolating DNA from a plant tissue, why is the mixture blended?
To break up the cell walls, so DNA is fully released from cell
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When isolating DNA from a plant tissue, how is the blended mixture filtered?
Through coffee filter paper- has larger pores and so faster filtration.
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When isolating DNA from a plant tissue, why is the blended mixture filtered?
Allows the DNA to be separated from the other broken remains of the cells.
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When isolating DNA from a plant tissue, why is protease added into the onion extract?
It breaks down the protein around the DNA
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When isolating DNA from a plant tissue, what is added to the onion extract (filtered mixture)?
Drops of protease enzyme to break down the protein around the DNA
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When isolating DNA from a plant tissue, what cold substance is poured onto the surface of the onion extract with protease?
- Ice cold ethanol
- Ethanol- helps to separate and isolate the DNA from the solution it’s in
- Ice cold- causes DNA to be insoluble
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When isolating DNA from a plant tissue, why is the ethanol ice cold?
Causes DNA to be insoluble
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When isolating DNA from a plant tissue, why is ethanol used?
Helps to separate and isolate the DNA from the solution it’s in
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When isolating DNA from a plant tissue, what happens once ice cold ethanol is added to onion extract?
DNA forms at the interface of the ethanol and extract.
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When isolating DNA from a plant tissue, how is the DNA drawn out of the boiling tube?
Draw DNA out of the solution by wrapping it around glass rod. (Twist/swirl)
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When isolating DNA from a plant tissue, what equipment is used? (15)
- Graduated cylinder
- Washing up liquid
- Salt
- Onion and knife
- Beaker
- Water bath at 60*
- Thermometer
- Ice bath
- Blender
- Funnel
- Coffee filter paper
- Protease enzyme
- Dropper
- Ice cold ethanol
- Glass rod
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In isolating DNA from plant tissue, explain the importance of chopping or making a paste of the plant tissue
- To break cell walls
- To increase surface area
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In isolating DNA from plant tissue, explain the importance of adding a detergent to the chopped tissue.
Breaks down membranes
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In isolating DNA from plant tissue, explain the importance of adding salt to the chopped mixture.
Causes DNA to clump.
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In isolating DNA from plant tissue, explain the importance of filtering the mixture?
Removes cell debris from the DNA.
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In isolating DNA from plant tissue, explain the importance of adding ethanol.
Removes the DNA
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In isolating DNA from plant tissue, describe the appearance of the DNA isolated in this investigation.
White material
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In isolating DNA from plant tissue, what is a safety precaution?
Wear safety gloves
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What are the steps (just asa few words)?
- Washing up liquid and salt
- Chopped onion
- Water bath 60*
- Ice bath
- Blend
- Filter
- Protease
- Ice cold ethanol
- DNA forms at surface
- Glass rod
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