DNA Profiling 2

Question 1

Why do you need to stain DNA

Answer 1

Need to do stain DNA with Southern blot because separated DNA is invisible.

Question 2

How to do southern blot

Answer 2

Do southern blot by:
Putting nitrocellulose sheet is placed on agarose gel
Paper towels placed on top (to draw up DNA fragments)
Apply strong alkali to denature DNA fragments
Alkali will want to move from liquid to paper towels and as it moves it, drags DNA with it and into nitrocellulose sheet. Add radioactive/fluorescent DNA probe

Question 3

Why do we use strong alkali in Southern blotting

Answer 3

We use strong alkali in Southern blotting because when DNA is in gel, it is still double stranded and by the time it has been dragged up to paper towel, DNA has been denatured and it now single stranded.

Question 4

What are DNA probes used for

Answer 4

DNA probes are used for checking for prescence of a particular sequence

Question 5

What are advantages of DNA profiling

Answer 5

Advantages of DNA profiling are:
Everyone’s DNA is unique
Several STR’S can be tested
DNA doesn’t change

Question 6

Dis adv of DNA profiling

Answer 6

Dis adv of DNA profiling are:
Genetically identical twins/close relative will have similar sequences so may show same profile
Possibility of 2 identical profiles from unrelated individuals
DNA profiling has many stages so contamination of DNA is likely

Question 7

Compare and contrast DNA profiling

Answer 7

Everyone’s DNA is unique but identical twins/relatives will have similar sequences
Several STR’S can be tested (chance of people with same genetic profile less than 1 in a billion) however, there is still a chance it could happen.
DNA doesn’t change it contamination is likely as DNA profiling has many stages

Question 8

What are uses of DNA profiling

Answer 8

Uses of DNA profiling are:
Identifying corpses
Paternity testing
Testing for genetic conditions

Question 9

What is an STR

Answer 9

An STR is 2-50 base pairs and can be repeated 5 to several times

Question 10

What is DNA probe

Answer 10

DNA probe is when complementary sequence of DNA is made to STR e.g AAA to TTT and it is fluorescent/radioactive so can be seen under UV light

Question 11

Why is DNA profiling used at crime scenes

Answer 11

DNA profiling is used at crime scenes because DNA profiling assumes everyone’s DNA is different except from identical twins, analyses STR and not exons because exons are hyper variable. Also, large number of introns