Molecular Genetics Lab Review - Kirchner-WHS-Biology


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

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Genetics Lab

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
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

No nuclear envelope surrounding chromosome

One single chromosome

Some contain plasmids resistant to certain drugs


Circular pieces of DNA

Outside the main bacterial chromosome

Carry their own genes for specialized

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

The Experiment


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


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

Smallest move the most quickly, thus migrate the

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


cut DNA into known fragment sizes

It will determine fragment sizes of DNA cut by