GN 301 Lecture Notes - Lecture 11: Blood Transfusion, Fetus, Mns Antigen System

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Published on 21 Dec 2017
GN 301
3.1 Linkage and Linked Genes
Tuesday, October 17, 2017
10:13 AM
Law of Independent Assortment
o Migration of allele on one gene does not affect migration of allele on other gene
o Equal amounts of 4 gamete types
o Genes on same chromosome
Linked genes travel as a single unit
Compete linkage= no crossing over
Possible to have crossing over
4 types of gametes not made in equal frequency
Parental (non-crossing over) more frequent than recombinant (crossover)
2 crossover regions less likely than 1 crossover region
The further genes are from each other, the more likely crossing over is possible
o Genes on diff. Chromosomes
Independent assortment
o Galactosemia and Albinism
Chromosome 9- both recessive
Very close
Different AaGg individuals will produce different gametes bc the alleles may be paired
up differently on the actual chromosomes ex: AG vs aG
Map Distances
o Relative distance btw loci found thru relative freq. of crossing over
o Units: centi-Morgan (cM)
1% of crossing over btw loci= 1 cM
o 20cM means 20% gametes will be recombinant
o Gametes produced will still use 2^(n) for heterozygous individuals but not equal frequency
Multiple Alleles
o More than 2 forms of the same gene
Person still only has 2 alleles
o Ex: Hemoglobin or ABO Blood
Alpha and beta chains; each chain has multiple alleles
ABO Blood
A and B are codominant and O is recessive
Antigenes on surface of RBC
o Geetis iolig ody’s atural defese agaist ifetio
o Antibody: made in resp. To entry of foreign protein
Viral invasion, snake bite, vaccines
o Antigen: substance that stimulates production of antibody
Foreign material
o Mismatched Blood Type
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