Download Genetics Objectives 15

Genetics Objectives 15
1.
Electrophoresis gel and restriction enzyme fragments:
 Note: recall that DNA is negatively charged, and will travel toward the
anode of the gel. Smaller pieces of DNA will not get caught in the gel and
will travel further toward the anode.
2.
Probe: a piece of genetic material that is complementary to a specific sequence.
Normally labeled in some manner so that it can be washed over a large amount of
DNA to find a specific sequence
Probe use in Southern and Northern blotting: after a gel has been run, the gel
is transferred and fixed to a nitrocellulose or nylon filter. The filter is then
washed by the probe, resulting in a labeled region where the sequence of interest
lies.
 Note: recall that Southern blots are DNA, Northern blots are RNA, and
Western blots are proteins
3.
Genetic linkage: proximity of two genes to each other. Due to crossing over,
genes on the same chromosome can be separated during meiosis. The closer the
genes are to each other, the less likely that a crossing over event will occur
between them, and the more closely linked they are.
Morgan (108 base pairs): the unit of length for one crossing over to happen
every time
CentiMorgan (106 base pairs): the unit of length for one crossing over to happen
1% of the time
4.
RFLP chromosome tracking and linkage in Southern blots: because
chromosomes have restriction sites in different areas, digestion of two different
chromosomes may yield different length products. These different length
products are called RFLPs and can be separated and analyzed in a Southern blot
(genes of interest may be linked to a specific RFLP and can therefore be used to
track a specific gene).
5.
PCR cascade diagram:
 Note: DNA is denatured, and primers anneal to the region of interest.
DNA polymerase then adds the complementary strands to make 2 strands
of DNA from 1. Then the process is repeated many times to create
numerous DNA clones from 1 strand.
6.
PCR and restriction enzyme use to track point mutations:
 PCR: primers can be designed to anneal to a specific sequence with a
point mutation and will therefore be unable to initialize the PCR reaction
in DNA without a mutation
 Restriction digest: if a point mutation is in a restriction site, then a
restriction digest will produce different sized RFLPs for normal and
mutated DNA. These can then be analyzed by using gel electrophoresis.