Non mendelian genetics
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Non-Mendelian Genetics. phenotype: purple. phenotype: white. phenotype: purple. Mendelian Genetics: Dominant & Recessive Review. One allele is DOMINANT over the other (because the dominant allele can “mask” the recessive allele). genotype: PP. genotype: pp. genotype: Pp. PP. Pp. Pp.

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Non-Mendelian Genetics

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Non mendelian genetics

Non-Mendelian Genetics


Mendelian genetics dominant recessive review

phenotype: purple

phenotype: white

phenotype: purple

Mendelian Genetics: Dominant & Recessive Review

  • One allele is DOMINANT over the other (because the dominant allele can “mask” the recessive allele)

genotype: PP

genotype: pp

genotype: Pp


Review problem dominant recessive

PP

Pp

Pp

pp

Review Problem: Dominant & Recessive

  • In pea plants, purple flowers (P) are dominant over white flowers (p). Show the cross between two heterozygous plants.

P p

GENOTYPES:

- PP (25%) Pp (50%)

pp (25%)

- ratio 1:2:1

P

p

PHENOTYPES:

- purple (75%) white (25%)

- ratio 3:1


Non mendelian genetics1

Non-Mendelian Genetics

  • Incomplete Dominance

  • Codominance

  • Multiple Alleles

  • Polygenic Traits

  • Sex-Linked Traits


Incomplete dominance

RR = red

rr = white

Rr = pink

Incomplete Dominance

  • a third (new) phenotype appears in the heterozygouscondition as a BLEND of the dominant and recessivephenotypes. Ex - Dominant Red (R) + Recessive White (r) = Hybrid Pink (Rr)


Problem incomplete dominance

R r

r

r

Rr

Rr

rr

rr

Problem: Incomplete Dominance

  • Show the cross between a pink and a white flower.

GENOTYPES:

- RR (0%) Rr (50%) rr (50%)

- ratio 1:1

PHENOTYPES:

- pink (50%); white (50%)

- ratio 1:1


Codominance

NS = some of each

SS = sickle cells

NN = normal cells

Codominance

  • in the heterozygous condition, both alleles are expressed equally with NO blending! Represented by using two DIFFERENT capital letters.

  • Example: Dominant Black (B) + Dominant White (W) = Speckled Black and White Phenotype (BW)

  • Sickle Cell Anemia -

sick


Codominance example speckled chickens

Codominance Example: Speckled Chickens

  • BB = black feathers

  • WW = white feathers

  • BW = black & white speckled feathers

  • Notice –

    NO GRAY!

    NO BLEND!

    Each feather is

    either black or white


Codominance example rhodedendron

Codominance Example: Rhodedendron

  • R = allele for red flowers

  • W = allele for white flowers

  • Cross a homozygous red flower with a homozygous white flower.


Codominance example roan cattle

Codominance Example:Roan cattle

  • cattle can be red (RR – all red hairs) white (WW – all white hairs) roan (RW – red and white hairs together)


Codominance example appaloosa horses

Codominance Example:Appaloosa horses

  • Gray horses (GG) are codominant to white horses (WW). The heterozygous horse (GW) is an Appaloosa (a white horse with gray spots).

  • Cross a white horse with an appaloosa horse.

W W

G

W

GW

GW

WW

WW


Problem codominance

NS

SS

SS

NS

Problem: Codominance

  • Show the cross between an individual with sickle-cell anemia and another who is a carrier but not sick.

N S

GENOTYPES:

- NS (50%) SS (50%)

- ratio 1:1

S

S

PHENOTYPES:

- carrier (50%) sick (50%)

- ratio 1:1


Multiple alleles

Multiple Alleles

  • there are more than twoalleles for a gene. Ex – blood type consists of two dominant and one recessive allele

    options. Allele A

    and B are

    dominant over

    Allele O (i)


Multiple alleles lab mouse fur colors

Multiple Alleles:Lab Mouse Fur Colors

  • Fur colors (determined by 4 alleles): black agouti yellow


Multiple alleles rabbit fur colors

Multiple Alleles:Rabbit Fur Colors

  • Fur colors (determined by 4 alleles): full, chinchilla, himalayan, albino


Multiple alleles blood types a b ab o

Multiple Alleles:Blood Types (A, B, AB, O)

  • Rules for Blood Types:

    A and B are co-dominant (Both show)

    AA or IAIA = type A

    BB or IBIB = type B

    AB or IAIB = type AB

    A and B are dominant over O (Regular dom/rec)

    AO or IAi = type A

    BO or IBi = type B

    OO or ii = type O


Multiple alleles blood types a b ab o1

Multiple Alleles:Blood Types (A, B, AB, O)


Problem multiple alleles

Ai

Ai

Bi

Bi

Problem: Multiple Alleles

  • Show the cross between a mother who has type O blood and a father who has type AB blood.

GENOTYPES:

i i

- Ai (50%) Bi (50%)

- ratio 1:1

A

B

PHENOTYPES:

- type A (50%) type B (50%)

- ratio 1:1


Problem multiple alleles1

Bi

AB

Ai

ii

Problem: Multiple Alleles

  • Show the cross between a mother who is heterozygous for type B blood and a father who is heterozygous for type A blood.

GENOTYPES:

A i

  • AB (25%); Bi (25%);

  • Ai (25%); ii (25%)

  • - ratio 1:1:1:1

B

i

PHENOTYPES:

  • type AB (25%); type B (25%)

  • type A (25%); type O (25%)

  • - ratio 1:1:1:1


Polygenic traits

Polygenic Traits

  • traits produced by multiple genes

  • example: skin color


Sex linked traits

Sex-Linked Traits

  • Gene is attached to the X chromosome only, not found on the Y chromosome at all. (women have XX, men have XY chromosomes). These disorders are more common in boys.

  • examples: red-green colorblindness


Sex linked traits1

Sex-Linked Traits

  • in males, there is no second X chromosome to “mask” a recessive gene. If they get an X with the disorder, they have it. Girls must inherit defective X’s from both parents.


Sex linked traits2

Sex-Linked Traits

A: 29, B: 45, C: --, D: 26

 Normal vision

A: 70, B: --, C: 5, D: --

 Red-green color blind

A: 70, B: --, C: 5, D: 6

 Red color blind

A: 70, B: --, C: 5, D: 2

 Green color blind


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