Download (HW) equilibrium

Male parents generally
DO NOT
Contribute cytoplasm to
zygotes
SO… mitochondria and chloroplasts are
MATERNAL CONTRIBUTIONS
Cytokinesis
(Cell Division)
-actin microfilaments
and Karyokinesis
(Nuclear division,
including mitosis)
-tubulin microtubules
Model for organelle division
From Dec 2003 Science
…..without implications for segregation
Maternal effect (NOT Maternal inheritance)
Genetic/genomic imprinting
Maternal imprinting
Paternal imprinting
If neither copy of 15q11 has paternal
imprinting, the result is Prader-Willi
syndrome (characterised by hypotonia,
obesity, and
hypogonadism).
If neither copy has maternal imprinting,
the result is Angelman syndrome
(characterised by epilepsy, tremors, and
a perpetually smiling facial expression).
‫גנטיקה של אוכלוסיות‬
Formula for allele frequency, based on knowledge of genotypes
A 3 allele case
In 3 allele case, same mathematical treatment
p = freq of IB = freq B (IBIB) + ½ freq of B (IBi) + ½ freq of AB (IBIA)
q = freq of IA = …
r = freq of i = …
p+q+r=1
YET:
Populations with different genotypes can have the same allele frequency
BUT, if there are random matings, the genotype
frequency of offspring is based on solely on the allele freq.
In next generation
Hardy-Weinberg
(H-W) Law
(& Chetverikov)
YET, if there are random matings, the genotype
frequency of offspring is based on solely on the allele freq.
Populations NOT
in H-W equilibrium
In next generation
Hardy-Weinberg
(H-W) Law
In this case:
If the processes below do not occur, a population is in
Hardy-Weinberg (HW) equilibrium, the following are unchanged:
Allele frequencies
Genotype frequencies
Phenotype frequencies
TEST: if these populations
are in H-W equilibrium, then:
If a population is in Hardy-Weinberg equilibrium,
the allele,genotype, and phenotype frequencies will
be stable as long as the HW requirements hold
H-W ‫ בשיווי משקל‬-- ‫הרבה אכלוסיות‬
‫ תיאור של אכלוסיה לפי תדירויות‬...‫אז‬
)'‫ מתאים (ו'חסכוני‬- ‫של אללים‬
2 allele case
Genotype
frequencies
Genotype
frequencies
M/M
N/N
M/N
p(M)
q(N)
We see HW equilibrium for ‘breeding populations’
We don’t expect HW for, say: the city of New York City
Lots of immigration
Not random matings, but many
distinct sub-groups
BUT, MANY human populations are in H-W equilibrium, for exampleMN tables we just saw, and:
Percent
Location MM MN
NN
p
q
Iceland 31.2 51.5 17.30 0.57 0.43
Greenland 83.5 15.6
0.9 0.92 0.08
How do HW populations “start” with different allele frequecies?
In human populations, often small founder populations:
How do HW populations “start” with different allele frequecies?
In human populations, often small founder populations:
Percent
Location MM MN
NN
p
q
Iceland 31.2 51.5 17.30 0.57 0.43
Greenland 83.5 15.6
0.9 0.92 0.08
If the processes below do not occur, a population is in
Hardy-Weinberg (HW) equilibrium, the following are unchanged:
Allele frequencies
Genotype frequencies
Phenotype frequencies
If these processes DO
occur, the populations
change.
-Each process can be
studied and quantitated
Selection of allele A: preferential survival
Haplotype
Inbreeding
0.5 X 0.5
‫ללמוד בבית על ‪Migration‬‬
Source of variation, deviation from HW:
migration (M) into a population
P is the allelic frequency in the donor population
And p0 is the original frequency among the recipients
M-migration rate
Originally
Yamane – not resistance to Gefilte-fish
Poland – 0.42 are resistance to Gefilte-fish
Current- among Yamane 0.046 are resistance
Thus DPtotal 0.046-0
P-P0 is 0.42-0
M= 0.046/0.42=1.095
Inbreeding
Source of variation: deviation from HW:
mutations have a slow effect on allele frequency (here, of w.t.):
Jan 3 start
Pseudo male - female cross in neurospora
Allele names according to phenotype
amorph
NULL
R~
R~
hypomorph
Wild type
R
R
hypermorph
R
R
neomorph
R~
R~
Standard Dominant – Recessive
Haploinsufficiency