Manipulating DNA : Coping DNA
Restriction enzymes cut DNA.
What do restriction enzymes come from?
come from various types of bacteria
Where is the DNA cut?
cut DNA at a specific nucleotide sequence called a restriction site.
What does it allow scientists to do?
allow scientists to more easily study and manipulate genes
What does each enzyme have?
has a different restriction site
What are sticky ends?
What are blunt ends?
cut straight across
How does gel electrophoresis work?
DNA is loaded into a gel that has a positive electrode at one end and a negative electrode at the other end. The DNA fragments (negatively charged) are pulled through the gel toward the positive electrode. The pores in the gel slow down larger fragments, and smaller fragments will travel a greater distance in a certain length of time.
List five ways in which scientists study and manipulate DNA.
artificial nucleotides to sequence genes, copying genes, chemical mutagens, computers, enzymes, bacteria
What is the nucleotide sequence at which a restriction enzyme cuts DNA called?
a restriction site
Why would different restriction enzymes cut the same DNA molecule into different numbers of fragments?
different restriction enzymes have different restriction sites
After DNA is cut with a restriction enzyme, how is the mixture of DNA fragments sorted?
by gel electrophoresis, on the basis of the size of the fragments
How do different fragments of DNA show up on a gel?
Different sizes of fragments show up as different lines, or bands, on the gel.
What information does a restriction map give about DNA? What information is not given by a restriction map?
the lengths of DNA fragments between restriction sites, but nothing about the DNA sequence
How are restriction maps used?
genetic engineering, studying gene mutations and diagnosing genetic disorders
What is PCR?
Polymerase chain reaction
What does PCR do?
technique that makes many copies of a particular segment of DNA
Why is PCR useful?
without many copies of DNA there is too little to study
What four materials are needed for PCR?
DNA to be copied, polymerases, nucleotides, two primers
Why are primers needed in the PCR process?
to start the new strands of DNA