11.2 COMPLEX PATTERNS OF INHERITANCE REFLECT simple dominance--traits are either dominant or...
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11.2 COMPLEX PATTERNS OF INHERITANCE REFLECT simple dominance--traits are either dominant or recessive CONSIDER traits such as height OBSERVE differences in height: shortest to tallest HYPOTHESIZE: is height simple dominance?
Transcript of 11.2 COMPLEX PATTERNS OF INHERITANCE REFLECT simple dominance--traits are either dominant or...
11.2 COMPLEX PATTERNS OF INHERITANCE
REFLECTsimple dominance--traits are either dominant or recessive
CONSIDER traits such as heightOBSERVE differences in height: shortest to tallestHYPOTHESIZE: is height simple dominance?
MENDEL’s EXPERIMENTS-ALL 7 traits were simple dominance-ALL 7 traits were inherited independently
EXCEPTIONS TO MENDEL’S LAWS-INCOMPLETE DOMINANCE-CO-DOMINANCE-SEX LINKAGE-MULTIPLE ALLELES-POLYGENIC TRAITS
Complex Inheritance of Traits do NOT follow Inheritance Patterns Mendel Described
INCOMPLETE DOMINANCE
INCOMPLETE DOMINANCE-”blended” traits Heterozygous genotype results in “mixture” of the 2 traits R=red r=white then Rr = pink
R R R rr
r
R
r
Rr Rr
Rr Rr
RR Rr
Rr rr100% pink 25% red/50% pink/25% white
*different amounts pigment— R most r least
INCOMPLETE DOMINANCE
CODOMINANCE
CODOMINANCE-”both” traits present in heterozygousR=red cow r=white cow Rr=roan cow (red & white)R R R r
r
r
R
r
Rr Rr
Rr Rr
RR Rr
Rr rr100% roan 25% red/50% roan/25% white *roan—BOTH red & white hairs
CODOMINANCE
CODOMINANCE
Sickle cell: BB-normal Bb=both bb=sickle cell
SEX DETERMINATION
23rd pair chromosomesdetermine gender
XX =
XY =
FEMALE
MALE
X y
X
X
XX Xy
XX Xy50%
50%
SEX LINKED TRAITS-Genes are carried on the sex chromosomes -Sex-linked genes on X chromosome ONLY– XBXB normal female– XBXb carrier female– XbXb affected female
– XBY normal male– XbY affected male
SEX LINKED TRAITS—“X-LINKED”
SEX CHROMOSOMES—some genes only on larger X chromosome, NOT on the smaller y chromosomeXB = dominant trait Xb = recessive trait
Red-green color-blindnessw/parents not CB (mom hetero)
males----Xby 50% CBfemales—XBXb 0% CB
*8% males have red-green CB
rare in females
XB y
XB
Xb
XBXB XBy
XBXb Xby
SEX LINKED TRAITS—“X-LINKED”
Xb yXB
Xb
XB YXb
Xb
XBXb XBy
XbXb XbY
XBXb Xby
XBXb XbY
50% girls CB/50% boys CB 0 girls CB/100% boys CB
Exceptions to Mendel’s LawsSex Linkage
Sex linked Inheritance in Drosophila
MULTIPLE ALLELES
More than 2 possible alleles for a trait
ABO BLOOD TYPES IA IB i
IA
IB
i
IAIA IAIB IAi -A- -AB- -A- IAIB IBIB IBi -AB- -B- -B- IAi IBi ii -A- -B- -O-
PHENOTYPE/GENOTYPES
A IAIA, IAi
B IBIB, IBi
AB IAIB
O ii
MULTIPLE ALLELES
BloodGroup(Phenotype)
O
Genotypes
AntibodiesPresent inBlood
Reaction When Blood from Groups Below Is Mixed with Antibodies from Groups at Left
O A B AB
A
B
AB
ii
IA IA
orIA i
IB IB
orIB i
IA IB
Anti-AAnti-B
Anti-B
Anti-A
MULTIPLE ALLELES
IA IB
i
i
IA i IB
i
IAIB IBi
IAi ii
IAi IBi
IAi IBi
AB / B / A / O 50% A / 50% B
HIEARCHY OF DOMINANCE IN ALLELES
-heirarchy of dominance in multiple allelesExample: rabbit coloringC -full coat color all blackCch -chinchila blended Ch -himilayan spotsc -albino white
Order of dominance—
C > Cch > Ch > c
POLYGENIC TRAITS
MELANIN least most aabbcc AaBbCc
AABBCC
POLYGENIC TRAITS- HAIR COLOR
-WHAT POSSIBLE EYE COLORS ARE THERE?-blue, green, brown
EXAMINE EACH OTHER’S EYES-What else do you notice about eye color?
HYPOTHESIZE: Is eye color inherited in a simple dominant/recessive manner-exact inheritance not determined-polygenic models have been made
THINK –PAIR- SHARE
POLYGENIC TRAITS- EYE COLOR
POLYGENIC TRAITSHETEROCHROMIA IRIDIUM—2 different color eyesCan result from trauma to the eyeCan be a altered gene
