Molecular Genetics Lab Review - Kirchner-WHS-Biology

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14 Δεκ 2012 (πριν από 4 χρόνια και 4 μήνες)

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Molecular
Genetics Lab
Review

Bacterial Transformation


Genetic transformation

host organism takes
in and expresses foreign DNA


Genetic engineering

manipulation of an
organism’s genome using DNA technology


Introduction of foreign DNA into organism


You used antibiotic
-
resistance plasmids to
transform
E. coli


If bacteria incorporates the foreign
DNA, they became ampicillin resistant


E. coli


Most common bacterium in human gut


Studied extensively


Important research organism


Reproduce rapidly


A single cell can divide to form millions of cells
overnight


No nuclear envelope surrounding chromosome


One single chromosome


Some contain plasmids resistant to certain drugs

Plasmids


Circular pieces of DNA


Outside the main bacterial chromosome


Carry their own genes for specialized
functions


Plasmids can be used in genetic engineering to
introduce foreign genes into a bacterium

The Experiment





Results




Gel Electrophoresis

Restriction Enzymes


Bacteria have enzymes that
cut (or digest) the DNA of foreign organisms to
protect themselves


Scientists have isolated several hundred of
these enzymes, restriction enzymes


Each is able to recognize and cut at a specific
DNA sequence, the recognition sequence


DNA fragments can be analyzed and used

The Experiment


You used restriction enzymes to cut
DNA into fragments


You used gel electrophoresis to
separate the samples of DNA that
had been cut


You compared fragments
of unknown size to
fragments of a known size
to calculate the unknown
fragment sizes

Restriction Enzymes


Restriction enzymes are specific to an exact
recognition sequence


Sticky ends & Blunt ends

Gel
Electrophoresis


Separates molecules of the rate of movement
through a gel under electricity


DNA is negatively charged

will move toward
positive pole of the gel


Different sized fragments move at different
rates


Smallest move the most quickly, thus migrate the
farthest


Analysis of Results


Each fragment is a particular number of
nucleotides long


To find out the size of the unknown DNA
fragments, you ran it along side DNA with
known fragment sizes


HindIII

cut DNA into known fragment sizes


It will determine fragment sizes of DNA cut by
EcoRI

Graphing
HindIII