SB3cii - DNA extraaction

how narrow is DNA?

about 2 nm (nanometre)

what is a safety measure needed to be taken when extracting DNA?

wearing eye protection

what is step one of DNA extraction?

mash the fruit with salt and water to separate cells

what does step 1 do?

breaks apart the cells from each other and starts to break down cell walls

why is salt used?

so that the DNA is more likely to clump together in the final stage

what is step 2 of DNA extraction?

sieve the mixture

what does step 2 help do?

collect fruit soup that contains all fruit cells with DNA inside the nucleus

what is step 3?

add detergent to rapture the cell membranes

what is an example of detergent?

washing up liquid

what does step 3 do?

breaks apart cell membrane surrounding the cell and nucleus and releases DNA (by adding detergent)

what is step 4 of DNA extraction?

add protease enzyme to uncoil the DNA

what are examples of products that contain protease enzymes?

pineapple juice, contact lenses cleaner, of a pinch of meat tenderiser

what does step 4 help do?

break down the proteins the DNA is wound tightly around

what is the form of DNA will now be after step 4?

present in the mixture as long strings

why can you not yet see the DNA in the mixture after step 4?

it is dissolved in the mixture

what do you have to do to make the DNA visible after step 4?

make it insoluable

what is step 5 of DNA extraction?

add ice cold ethanol to slow down the enzymes

why is the ethanol at a low temperature?

to slow down the action of enzymes naturally present in the cell

what do the enzymes cold ethanol slows down do?

break down the DNA

why did the enzymes ethanol slows down don’t break down DNA in a normal healthy cell?

they are usually kept separate from DNA by the nucleus cell membrane, but it was raptured earlier in step 3 by the detergent

why does the ethanol forms a layer on top of the fruit soup?

it is denser than water

what is the salted DNA after step 5?

insoluble in ethanol

what happens to the insoluble salted DNA after step 5?

it begins to precipitate out of the fruit soup at bounding between the soup and the ethanol

what happens to the DNA in step 5?

it transforms from a dissolved solute into an insoluble substance in the ethanol layer

what is formed in the mixture after step 5?

layers of soup fruit, than DNA then ethanol

what is step 6 of DNA extraction?

use a wooden stick to remove DNA

what does the DNA looks like when extracted?

cloudy white strings