Gregor Johann Mendel (1822 - 1884) Gregor Johann Mendel (1822 - 1884)
Gregor Mendel 1822 – 1884 C.E.
description
Transcript of Gregor Mendel 1822 – 1884 C.E.
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Gregor Mendel1822 – 1884 C.E.
StamensCarpel
Parentalgeneration(P)
TECHNIQUE
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2
3
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Firstfilialgener-ationoffspring(F1)
RESULTS5
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EXPERIMENT
P Generation(true-breeding parents) Purple
flowers Whiteflowers
F1 Generation (hybrids) All plants had
purple flowers
F2 Generation
705 purple-floweredplants
224 white-floweredplants
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Allele for purple flowers
Homologouspair ofchromosomes
Locus for flower-color gene
Allele for white flowers
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P Generation
Appearance:Genetic makeup:
Gametes:
Purple flowers White flowersPP
P
pp
p
F1 Generation
Gametes:
Genetic makeup:Appearance: Purple flowers
Pp
P p1/21/2
F2 GenerationSperm
Eggs
P
PPP Pp
p
pPp pp
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Phenotype
Purple
Purple3
Purple
Genotype
1 White
Ratio 3:1
(homozygous)
(homozygous)
(heterozygous)
(heterozygous)
PP
Pp
Pp
pp
Ratio 1:2:1
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1
2
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TECHNIQUE
RESULTS
Dominant phenotype, unknown genotype:
PP or Pp?
Predictions
Recessive phenotype, known genotype: pp
If PP If PporSperm Sperm
p p p p
P
P
P
pEggs Eggs
Pp
Pp Pp
Pp
Pp Pp
pp pp
orAll offspring purple 1/2 offspring purple and
1/2 offspring white
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EXPERIMENT
RESULTS
P Generation
F1 Generation
Predictions
Gametes
Hypothesis ofdependentassortment
YYRR yyrr
YR yr
YyRr
Hypothesis ofindependentassortment
orPredictedoffspring ofF2 generation
Sperm
SpermYR
YR
yr
yr
Yr
YR
yR
Yr
yRyr
YRYYRR
YYRR YyRr
YyRr
YyRr
YyRr
YyRr
YyRr
YYRr
YYRr
YyRR
YyRR
YYrr Yyrr
Yyrr
yyRR yyRr
yyRr yyrr
yyrr
Phenotypic ratio 3:1
EggsEggs
Phenotypic ratio 9:3:3:1
1/21/2
1/2
1/2
1/4
yr
1/4 1/4 1/41/4
1/4
1/4
1/4
1/43/4
9/163/16 3/16
1/16
Phenotypic ratio approximately 9:3:3:1315 108 101 32
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Rr RrSegregation of
alleles into eggs
Sperm
R
RR R
R
R rrr
r
r
r1/2
1/2
1/2
1/2
Segregation ofalleles into sperm
Eggs1/4
1/4
1/41/4
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Red
P Generation
Gametes
WhiteCRCR CWCW
CR CW
F1 GenerationPinkCRCW
CR CWGametes 1/21/2
F2 Generation
Sperm
Eggs
CR
CR
CW
CW
CRCR CRCW
CRCW CWCW
1/21/2
1/2
1/2
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IA
IB
i
ABnone
(a) The three alleles for the ABO blood groups and their associated carbohydrates
Allele Carbohydrate
GenotypeRed blood cell
appearancePhenotype
(blood group)
IAIA or IA i A
BIBIB or IB i
IAIB AB
ii O
(b) Blood group genotypes and phenotypes13
BbCc BbCc
Sperm
EggsBC bC Bc bc
BC
bC
Bc
bc
BBCC
1/41/4
1/41/4
1/4
1/4
1/4
1/4
BbCC BBCc BbCc
BbCC bbCC BbCc bbCc
BBCc BbCc
BbCc bbCc
BBcc Bbcc
Bbcc bbcc
9 : 3 : 4
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Eggs
Sperm
Phenotypes:Number ofdark-skin alleles: 0 1 2 3 4 5 6
1/646/64
15/6420/64
15/646/64
1/64
1/8
1/8
1/8
1/8
1/8
1/8
1/8
1/8
1/81/8
1/81/8
1/81/8
1/81/8
AaBbCc AaBbCc
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Amniotic fluidwithdrawn
Fetus
PlacentaUterus Cervix
Centrifugation
Fluid
Fetalcells
Severalhours
Severalweeks
Severalweeks
(a) Amniocentesis (b) Chorionic villus sampling (CVS)
Severalhours
Severalhours
Fetalcells
Bio-chemical
tests
Karyotyping
Placenta Chorionicvilli
Fetus
Suction tubeinsertedthroughcervix
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