gel electrophoresis

DNA identification

1. Isolate the DNA in a sample, and if needed, make copies: 2. Cut the DNA into shorter fragments that contain known VNTR areas: 3. Sort the DNA by size: 4. Compare the size fragments in the unknown sample of DNA to those of known samples of DNA.

how big is DNA molecules

3 meters

what helps to make the bands of DNA visible

A chemical in the gel that the DNA passes through binds to the DNA and is visible under UV light.

why are they moving through the gel?

As the DNA is negatively charged it will move from the well towards the bottom of the gel which is positive

how is a DNA fingerprint used to identify unknown DNA samples or used in making medical diagnosis

It takes fragments are used to identify a person's DNA fingerprint. and used in medicine to diagnose hereditary genes

what is different in the movement of the short vs longer molecules in a gel electrophoresis

Shorter ones will move faster through the gel than longer ones

How are DNA molecules sorted by a gel?

The gel acts like a sieve, separating different DNA molecules according to their size, as smaller DNA molecules will be able to move through the gel quicker than larger molecules.

running buffer

What allows a current to travel through the gel tray

how do molecules move through the gel in gel electrophresis process

an electric current passes DNA samples through a gel

Why is it called a DNA fingerprint?

because it is very unlikely that any two people would have exactly the same DNA information, in the same way that it is very unlikely that any two people would have exactly the same physical fingerprint.

casting tray

casting tray is to make sure the gel is not contaminated

comb

comb is to make the holes to put the dna in To ensure there's a place to put the DNA in the gel, a comb is placed in the agarose liquid before it cools. Each tooth in the comb will become a hole, or 'well,' in the solidified agarose gel.

electricity

electricity is so that each substance will seperate

gel box

gell box is to make sure the electricity goes directly to the gel

bumper

placed at the end of the casting tray and removed when the agarose gel hardens

role of restriction enzymes in the gel electrophoresis process

recognizes and cuts, or digests, only one particular sequence of nucleotide bases in DNA, and it cuts this sequence in the same way each time. Typically restriction enzymes used in cloning recognize four-,six, or eight base sequences. Hundreds of restriction enzymes are known, each producing DNA fragments with characteristic ends. Restriction enzymes can cut blunt ends (cuts directly opposite each other) or sticky ends (staggered cuts)

restriction enzymes

restiriction enzimes were to cut the DNA at a certain point

loading and staining dyes

staining dies were to show the process and to show each different type

well

the well is so that the electricity can reach the gel,

how do restriction enzymes function

they leave overhanging "sticky" ends recognizes a specific sequence of DNA and cuts it in a specific way

3 scenarios where a DNA fingerprint is useful

to convict someone of murder. to identify an unknown body. to determine is you carry a hereditary gene that can cause an illness

agarose gel

used to separate fragments of DNA based on size. The hot agarose liquid is poured into a casting tray. Once the mixture cools, a thin agarose brick will form.

Micropipettes

were to insert the dna into the wells.

five cell types that could be used as a source of DNA for a fingerprint?

white blood cells from blood, hair, skin, saliva, semen