non-mendelian inheritance
DESCRIPTION
Non-Mendelian Inheritance. . AaBbCc. AaBbCc. Sperm. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. 1 / 8. Eggs. 1 / 8. 1 / 8. 1 / 8. 1 / 8. Phenotypes:. 1 / 64. 6 / 64. 15 / 64. 20 / 64. 15 / 64. 1 / 64. 6 / 64. Number of - PowerPoint PPT PresentationTRANSCRIPT
Non-Mendelian Inheritance
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
Polygenetic Inheritance-a trait is controlled by more than two alleles. Each
dominant allele has a
quantitative effect
Ex. Skin color
3
Height in Human Beings
4
Frequency Distributions in
Polygenic Inheritance
Sex Determination-out of 46 only 2 are sex chromosomes = X &
Y- XX = female, XY = male-44 are autosomes- code for everything else
Sex Linked Genes- Carried on only the X or Y chromosome - Ex: Color blindness is a recessive trait carried
only on the X chromosome (XC or Xc ). A female needs to be Xc Xc to get it, but a male only has to be Xc Y to get it. So more males are color blind.
XC XC XC Xc
XC Y Xc Y
XC Xc
XC
Y
Numbers That You Should See If You Are In One Of The FollowingFour Categories: [Some Letter Choices Show No Visible Numbers]
4 Sex-Linked Traits:
1. Normal Color Vision: A: 29, B: 45, C: --, D: 26
2. Red-Green Color-Blind: A: 70, B: --, C: 5, D: --
3. Red Color-blind: A: 70, B: --, C: 5, D: 6
4. Green Color-Blind: A: 70, B: --, C: 5, D: 2
Pedigree- a chart showing genetic inheritance
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Autosomal Recessive Pedigree Chart
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Autosomal Dominant Pedigree Chart
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Autosomal Recessive Disorders• Tay-Sachs Disease
– Progressive deterioration of psychomotor functions. Lipid accumulation in brain cells. Death in childhood
• Cystic Fibrosis
– Mucus in bronchial tubes and pancreatic ducts is particularly thick and viscous
• Phenylketonuria (PKU)
– Lack enzyme for normal metabolism of phenylalanine. Mental retardation
Albinism- lack of pigment (melanin)
Sickle Cell (homozygous)
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Cystic Fibrosis Therapy
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Autosomal Dominant Disorders• Alzheimers (mental deterioration)
• Achondroplasia (dwarfism)
• Neurofibromatosis Tan or dark spots develop on skin and darken Small, benign tumors may arise from fibrous nerve coverings
• Huntington Disease Neurological disorder Progressive degeneration of brain cells
• Severe muscle spasms
• Personality disorders
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A Victim of Huntington Disease
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Huntington Disease:Normal and Diseased
Brain
Incomplete Dominancethe alleles are blended together to form an
intermediate phenotype - example:snap dragon color (red, white or pink)
Co-Dominance- Both alleles are expressed in the
phenotype (ex. Sickle cell anemia) BB= normal cell bb=sickle cell Bb Both (carrier)
Blood Type-Co-dominant:-caused by multiple alleles – 3 or more
typesA = has only A carbs. B = has only B carbs.AB = both AB carbs.O = no carbs.
GenotypeRed blood cell
appearancePhenotype
(blood group)
A
B
AB
O
Fig. 14-11
IA
IB
i
A
B
none(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 phenotypes
RH factor-Rhesus factor- antigens on the surface of blood cells that
can cause an immune response
- Positive (+) blood has antigens
- Negative (-) blood has no antigens
-a negative mother could harm a positive fetus.
-a negative person getting positive blood can be harmed
Epistasis • One gene alters the expression of another gene
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
Pleiotrophy• Some genes control more than one trait. (ex. Pea
flower and seed color are controlled by one gene)
Multifactorial genetics• Multifactorial traits are affected by genotype and the
environment
• Norm of reaction-phenotype range (more acid or aluminum results in darker flowers
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Himalayan Rabbits