Bio 219 Final Exam: Questions And Answers (Accurate
& Verified)
Most restriction enzymes recognize specific [x] sequeces that are most
commonly [y] base pairs in length. Right Ans - X - palindromic
Y- 6
Why was the vector we are using to clone the lux operon named pGEM?
a.
Because it can be cut 2x within the MCS to allow for insertion of the
chromosomal fragments.
b.
Because it has two promoters.
c.
Because it has two multiple cloning sites (MCS).
d.
Because it has two selectable markers. Right Ans - b. Because it has two
promoters
Restriction enzymes make different kinds of cuts on DNA and leave the ends
in a variety of fashions. Which of the following type of ends is more more
efficient for cloning DNA into vectors?
a.
Loose ends
b.
Medial ends
c.
Sticky ends
d.
Fixed ends
e.
Blunt ends Right Ans - c. Sticky ends
When restriction enzymes cut through a piece of DNA they either leave sticky
or blunt ends behind. Sticky ends are characterized by having over-hangs.
These 2 or 3 nucleotides may aid in ligating with compatible pieces of DNA
,through hydrogen bonding. This hydrogen bonding of these over-hangs makes
cloning with sticky ends 10-100x more efficient. Blunt ends can be used in
cloning but they are much less efficient. Blunt ends are when the restriction
enzyme makes a clean cut through the DNA and leaves no over-hangs making
it more difficult to hold the segment of DNA in place.
Bam HI was included in our double digest because it will generate the same
size 9 kb fragment containing the lux operon so we will have double the
chance of getting a lux operon clone.
True
False Right Ans - False
Bam HI generates an 18 kb fragment that contains the lux operon. We are
hoping that additional cutting with Bam HI will make it easier for Sal I to
work. It is easier to clone smaller fragments (9 kb) but using the BamHI may
help to release the larger restriction fragment from the chDNA so Sal I can
trim it to the 9 kb size.
If you wanted to clone a seuqence that was 300 kb in size, which vector would
you choose?
a.
Plasmid vector
b.
Phagemid
c.
Bacteriophage vector
d.
Cosmid vector
e.
Bacterial Artificial Chromosome (BAC) Right Ans - e. Bacterial Artificial
Chromosome (BAC)
DNA, chromosomal or plasmid, exists in a supercoiled state when undisturbed
in a cell.
True
False Right Ans - True
, DNA folds in upon itself into a supercoiled state when there are no breakages
or damage to the strands. This supercoiling saves "space" and protects the
DNA from exogenous harm. Because DNA supercoils upon itself, visualization
on a gel with be altered. Since DNA moves according to size and charge, the
size being smaller than normal pushes the band further down a gel, making it
appear smaller.
In shotgun cloning, the goal is to target a specific size insert from the genome
for insertion into a vector to generate an exclusive population of clones with
your gene of interest.
True
False Right Ans - False
Shotgun cloning is a random process where digested fragments of many
different sizes of the genome are generated and then inserted into a vector.
Each vector contains a piece of the genome with the goal of representing the
entire genome so that hopefully your gene of interest is present in your
population of clones.
If you had an A:T rich genome and wanted to cut less frequently, which
restriction enzyme would you choose?
a.
Sma I that recognizes 5'-CCCGGG-3"
b.
EcoRI that recognizes 5'-GAATCC-3' Right Ans - a. Sma I that recognizes 5'-
CCCGGG-3"
It would be harder for the Sma I to find its recognition sequence in a A:T rich
genome.
Which of the following is NOT a property of a good vector?
a.
A multiple cloning site (MCS) that contains the restriction site for numerous
restriction enzymes.
b.
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