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Lecture

Bio lab 5 notes Nov 30 2009

by OC4

Department
Biology
Course Code
BIO120H1
Professor
Ingrid L.Stefanovic

Page:
of 2
Bio lab 5
Population must be able to adapt to the environment due to genetic variation
Example: the freat lakes fishery
Loss of genetic diversity t overexploitation combined with invasion be exotic species has placed severe
on native fish species
Selection: natural process, many of the forces that select the fish population in great lake is due to
human t favor certain individuals and reduce the overall diversity of genetics
Gene flow: exchange of alleles between neighbouring populations. Geographically, few barriers and the
closer two population could be t more likely to exchange.
Less gene flow t maintain the diversity of the population as a whole
Genetic drift: most in small population t gene lost t reducing the amount of genetic variation in
population
Raised frys in laboratory reduces the genetic variation in the whole population due to just few male and
females are used initially
Large hatchery-raised P poses potential problems of native species:
1. Limit the ability for to adapt to the environment for a whole P
2. Raise the competition and may introduce diseases t therefore reduce the native P
Measuring Genetic variation:
Cellulose actate electrophoresis: -- advantages t larger amount individuals and shorter time
Main types of gel electropresis: cellulose acetate, starch, polyacrylamide and agarose
Enzymes: are proteins composed of one or more polypeptide chains(strands of amino acids)
If an enzyme can lead to a difference of the overall charge of the enzyme t move at adifferent rate
Enzymes of the same size and shape move at a rate determined largely by the ratio of positively-charged
to negatively-charged amino acids.
Different forms of those enzymes are called allozymes
Monomer t one polypeptide = one protein one F and one S
Dimer t the complete enzyme consists of two polypeptides t three different bands
W}oÇu}Z]o}]W](Zu}}uu}vooo[(µvÇ]PZvìñUZo}µu}o]loÇ}
monomorphic.
H t average frequency of heter individuals per locus of the population
Differentiate the genetic variation between two species:
Using I(genetic identity) and D(genetic distance)
I range from 0 to 1 D can range from 0 to infinite
D=ln(-I)
Closely related populations tend to show I bigger than 0.9 and D smaller than 0.1
Divergent related population tend to show I smaller than 0.8 and D bigger than 0.2
While I decrease and D increases
Lab: compare zebre mussels and quagga mussels:
Steps:
While testing whether the loci is hybridized or not t use electrophorsis to test on large amount of
individuals t obtain the gel and see if there is any heterozgyotes~
1. Sock the gel: shine side and dull side t lower the gel gently and steadily into the buffer at a rate of
about 1cm/s
2. Identify species t round rear t quagga, sharp rear t zebra
3. Prepare tissue sample.
4. Load the sample plate
5. Set up the applicator t keep the gel[s dull side up
6. Transfer the sample to gel
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7. Applies tacking dye
8. Electrophorese the samples t gel is facing down and the shiny side is facing up t the gel contacts the
wick
9. Stain the gel t stain the dimeric enzyme malate dehydrogenase (MDH)
Before the gel is removed from the chamber t add PMS to the solution
After gel is removed add molten agar to solutiont stir quicky and pour it very fast to the gel
10. Incubate the gel
11. Get interpretation t MDh is encoded by 2 different loci t MDH-1 AND MDH-2
MDH-1 will run to the positive charge
And MDH-2 will run to the negative charge
Isozymes t multiple forms of an enzyme that are encoded from multiple loci
Just analysis MDH-2, because more clear t two form F &S
Null hypothesis t the population is in Hardy-Weinberg equilibrium at the loci!
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