Beyond Dominant and Recessive

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Beyond Dominant and Recessive

• Non-Mendelian Inheritance
• Chapter 10-3 (eye book)

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?

• This means traits that dont fit Mendels
  patterns of inheritance

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Co - Dominance

• In co dominance, there are three phenotypes.
• For this type of inheritance, there are two
  dominant traits.
• This time, both dominant traits show in the
  heterozygous phenotype
• For example The two dominant traits of this
  type of fowl are white and black. The
  heterozygous phenotype appears speckled

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Co Dominance

• The way we write alleles for this type of
  inheritance is with two different capital
  letters.
• Each dominant trait gets its own letter
• The heterozygous genotype gets both capital
  letters

Red RR Stripes RW White WW
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Practice

• Look at all the cows. What are all the
  phenotypes?
• Which two traits are dominant, which is the mixed
  trait?
• What notation will you use to represent
• The brown cow?
• The white cow?
• The speckled?

BB
WW
BW
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Incomplete Dominance(Also called Intermediate
inheritance)

• In incomplete dominance, there are three
  phenotypes. The heterozygous phenotype is halfway
  in between the two other phenotypes
• This is referred to as blending

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Incomplete Dominance(Also called Intermediate
inheritance)

• Since one phenotype is not dominant over the
  other, the homozygous phenotypes are both
  considered dominant.

Red Dominant Pink Blended White Dominant
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Incomplete Dominance(Also called Intermediate
inheritance)

• The way we write alleles for this type of
  inheritance is with letters and superscripts.
• We pick one letter to represent the trait
• (ex C for color)
• We use superscripts to represent the expression
  of the trait
• (ex two different capital letters, for each
  dominant trait)

Red CRCR Pink CRCW White CWCW
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Practice

• Look at all the fish. What are all the
  phenotypes?
• Which two traits are dominant, which is the
  blended trait?
• What notation will you use to represent
• The blue fish?
• The red fish?
• The purple fish?

CBCB
CRCR
CRCB
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Lethal Allele

• When an organism with a particular genotype does
  not survive
• Example Mexican Hairless Dogs
• Dogs with the genotype HH do not develop and are
  never born. The resulting phenotype ratio is 2
  hairless 1 with hair

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Lethal Allele

• This is like Mendelian genetics because
• There are only two phenotypes
• We use the same letter in capital and lower case
• This is different than Mendelian genetics
  because
• You never get a 31 ratio you get a 21 ratio
  instead

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Multiple Alleles

• Some traits have more than two possible alleles.
• Organisms still get two alleles, one from each
  parent
• This increases the number of possible genotypes
  and phenotypes

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Multiple Alleles

• Human blood type is a good example of a trait
  with multiple alleles.
• There are 4 different blood types A, B, AB or O,
  which refer to a specific carbohydrate on the red
  blood cells

Phenotype (Blood type) Genotype
O IOIO
A IAIA or IAIO
B IBIB or IBIO
AB IAIB
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Copy this flowchart into your notes!!!
Start
3 phenotypes
2 phenotypes
Blending
Both traits show
21 ratio
All other ratios
Co-dominance
Incomplete Dominance
Lethal
Mendelian
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White Horses
Brown Horses
Tan Horses

• What type of inheritance is shown?
• What gene symbols (letters) should you use to
  represent each phenotype?
• 3. What parent cross led to this population?
• Prove it with a Punnett Square

All Tan Horses
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brown puppies
Brindle (striped tan and brown) puppies
Tan puppies

• What type of inheritance is shown?
• What gene symbols (letters) should you use to
  represent each phenotype?
• What parent cross led to this population?
• Prove it with a Punnett Square

Half tan puppies and half brindle puppies
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More Practice

• 100 white fish B) 100 red fish
  C) 66 red fish
• 33 white fish
• 1. Mode of Inheritance
• 2. Gene Symbol (Letters) for each phenotype
• 3. Parent cross that gave us population A)
• B) C)

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Warm Up
Population 3 50 Red fish and 50 striped fish
Population 1 100 White fish
Population 2 100 Striped fish

• 1. What type of inheritance is shown? all three
  have the same
• ( Mendelian / Incomplete dominance / Co-dominance
  / Lethal)
• (Use your flow chart from yesterday to
  find out!!!)
• What are the three phenotypes present?
• (Look at the fish, and write down the three
  types you see)
• 3. What gene symbols (letters) should you use to
  represent each phenotype?
• (Use your notes from yesterday to find
  out!!!)
• 4. What are the genotypes of the fish in each
  population?
• (Match your answer from 3 to each
  population of fish)

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MOI Table

• Mendelian and Lethal Parental Crosses
• Non Mendelian Parental Crosses

RR x RR RR x Rr RR x rr Rr x Rr Rr x rr rr
x rr
RR x RR RR x RW RR x WW RW x RW RW x WW WW
x WW CWCW x CWCW CWCW x CWCR, CWCW x
CRCR CWCR x CWCR CWCR X CRCR CRCR X CRCR
NOTE All Examples are for Red and Whiteyou can
use ANY letters