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4.3 TheoreticalGenetics. To be able to define the key terms of theoretical genetics To describe inheritance patterns using inheritance diagrams To be able to explain sex linkage. Definitions. Genotype: the alleles of an organism Phenotype: The characteristics of an organism - PowerPoint PPT Presentation
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4.3 THEORETICALGENETICS To be able to define the key terms of
theoretical genetics To describe inheritance patterns using
inheritance diagrams To be able to explain sex linkage
DEFINITIONS
Genotype: the alleles of an organismPhenotype: The characteristics of an organismDominant allele: the allele that gets expressed in heterozygous conditionRecessive allele; the allele that has an effect on the phenotype when present in the homozygous state.Codominant alleles: pairs of alleles that are both expressed when presentLocus: specific position of a gene in a chromosomeHomozygous; having two copies of the same allele.Heterozygous: having two different alleles of a geneCarrier: a person with one recessive faulty allele for a genetic disorderTest cross: testing a suspected heterozygote by crossing with the homozygous recessive
MONOHYBRID CROSSES
Complete Dominance
Incomplete Dominance
Codominance
#1 - COMPLETE DOMINANCEP: RR rrF1: Genotype Phenotype Type of Genotype
Rr red heterozygousF1 Cross: Rr RrPunnett Square:
F2: Genotype Phenotype Type of GenotypeRR red homozygousRr red heterozygousRr red heterozygousrr white homozygous
RR Rr
Rr rr
R
r
R r
F2 Genotypic Ratio:1 RR : 2 Rr : 1 rrF2 Phenotypic Ratio:3 red: 1 white
#4 - INCOMPLETE DOMINANCEP: RR rrF1: Genotype Phenotype Type of Genotype
Rr pink heterozygousF1 Cross: Rr RrPunnett Square:
F2: Genotype Phenotype Type of GenotypeRR red homozygousRr pink heterozygousRr pink heterozygousrr white homozygous
RR Rr
Rr rr
R
r
R r
F2 Genotypic Ratio:1 RR : 2 Rr : 1 rrF2 Phenotypic Ratio:1 red: 2 pink : 1 white
#7 - CODOMINANCEP: RR WWF1: Genotype Phenotype Type of Genotype
RW red & white heterozygousF1 Cross: RW RWPunnett Square:
F2: Genotype Phenotype Type of GenotypeRR red homozygousRW red & white heterozygousRW red & white heterozygousWW white homozygous
RR RW
RW WW
R
W
R W
F2 Genotypic Ratio:1 RR : 2 RW : 1 WWF2 Phenotypic Ratio:1 red : 2 red & white : 1 white
ABO BLOOD TYPING
ABO BLOOD TYPING% of Blood Types in U.S. Caucasions
O+38%
O-7%AB+
3%AB-1%
A+34%
A-6%
B+9%
B-2%
ABO BLOOD TYPING
ABO BLOOD TYPING
A B AB O
A Y Y
B Y Y
AB Y
O Y Y Y Y
DONOR
RECIPIENT
#15 - BLOOD TYPINGP: IAi IBiPunnett Square:
F1: Genotype PhenotypeIAIB ABIAi AIBi Bii O
IAIB IAi
IBi ii
IA
i
IB i
ADDITIONAL CROSSES
Sex Determination
Sex Linkage
ABO Blood Typing
#12 - SEX LINKAGE- HAEMOPHILIAP: XHY XHXh
Punnett Square:
F1: Genotype Phenotype Sex Type of GenotypeXHXH normal F homozygousXHXh carrier F heterozygousXHY normal M hemizygousXhY hemophilia M hemizygous
XHXH XHXh
XHY XhY
XH
Y
XH Xh
#11 - SEX DETERMINATIONP: XY XX
XX XX
XY XY
X
Y
X X
Ratio:1 XX : 1 XY
DIHYBRID CROSSES
Complete Dominance
#8 - COMPLETE DOMINANCEP: yyrr YYRRF1: Genotype Phenotype Type of Genotype
YyRr yellow/round heterozygousF1 Cross: YyRr YyRrPunnett Square:
F2: Genotype Phenotype9 Y_R_ yellow/round3 Y_rr yellow/wrinkled3 yyR_ green/round1 yyrr green/wrinkled
yR
yr
YR
Yr
YYRR YYRr YyRR YyRr
YYRr YYrr YyRr Yyrr
YyRR YyRr yyRR yyRr
YyRr Yyrr yyRr yyrr
YR Yr yR yr
PEDIGREES
PEDIGREES
Normal
Affected
Carrier
PEDIGREESExample:You are a normal female (homozygous). Both of your parents are normal. Your younger brother is normal and your older brother has hemophilia.
You!
XHXh XHY
XHYXhY XHXH
#18 - PEDIGREES
XCXC XcYXCXc XCY
XCY XCXc XCY
XcYXCXC
You!