Question

Which of the following is NOT true of editing DNA?
A. DNA can be cut at specific places.
B. Restriction enzymes will cut a DNA sequence if it matches the sequence precisely.
C. Huge DNA molecules can be cut into smaller fragments.
D. It is easier for biologists to work with very large pieces of DNA than to work with smaller fragments.

Answer 1

"Take a look at this picture:
http://upload.wikimedia.org/wikipedia/en/thumb/0/01/Recombinant_formation_of_plasmids.svg/616px-Recombinant_formation_of_plasmids.svg.png

You see that circle? The ring.

It's a PLASMID.

A PLASMID is DNA molecule that is separate from the other set of chromosomal DNA.
PLASMIDS can replicate (copy) themselves separately from chromosomal DNA.

Take a look at this picture:
http://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Plasmid_%28english%29.svg/320px-Plasmid_%28english%29.svg.png

~~~~~~~~~

When we RECOMBINE DNA, in bacteria,
what we are doing is altering the plasmid DNA of the bacteria.

We cut the plasmid, using RESTRICTION ENZYMES.
(That's what restriction enzymes do. They cut DNA.)

After we cut the plasmid,
we put in another gene.
And then we glue it back together,
so that the new gene and the plasmid are combined.

Take a look at this article,
under "Desirable Properties of Plasmids":
http://dwb4.unl.edu/Chem/CHEM869N/CHEM869NLinks/mbclserver.rutgers.edu/~sofer/cloningvectors.html

The article tells us that it is actually easier to work with SMALLER DNA segments, than larger ones.

This is for many reasons.
Here are a few:

1. It is easier to get smaller DNA fragments into bacteria, than large fragments.

2. Small plasmid DNA molecules replicate faster.

3. Small plasmid molecules are less fragile."

Answer 2

b

Answer 3

thanks!!