Ill give you 20 + brainliest. points if you do this. (Watch the Bozeman science molecular biology video, complete the table as you watch)

what is the source of the chemical :bacteria/bacterial cells ?

why?:if a virus tries to attack the bacteria ,it uses restriction enzymes to fight it off .

.cleave foreign DNA,this eliminating infectious organisms..

EcoR1 restriction site

it is also part of the restriction modification system.In molecular biology it is used as a restriction enzyme .

why do we sometimes use multiple restriction enzymes?

..these enzymes cut both strand of the target DNA at different spots creating 3'-5' overhangs of 1 to 4 nucleotides.

to be able to clone a DNA insert into a cloning or expression vector ,both have to be treated with two restriction enzymes that create compatible ends.

what is the role of each of these chemicals in copying DNA?

primer

:is a short nucleic acid sequence that provides a starting point for DNA synthesis .this synthesis of a primer is necessary because the enzymes that synthesize DNA ,which are called DNA poly merases ,can only attack new DNA nucleotides to an existing strand of nucleotides .

tag polymerase:

Due to its key role in synthesizing and amplifying new strands of DNA ,Tag DNA Polymerase is essential to poly chain reaction PCR.

like other DNA polymerase can only produce DNA if it has primer,a short sequences of 20 nucloetides that provide a starting point for DNA synthesis.

nucleotides:

DNA is made up of a double helix of two complementary strands ,during replication ,these strands are separated .most prominently,DNA polymerase sythesizes the new strands by adding nucleotides that complement each strand .

DNA replication occurs during the S-Stage of interphase.

methods the separate pieces of DNA

.Gel electrophoresis is a technigue used to separate DNA fragments according to the size .

what pulls the pieces of DNA ?

DNA samples are loaded into wells at one end of a gel ,and an electric current is applied to pull them through gel.

why?

because all DNA fragments have the same amount of change per mass ,small fragments move through the gel.