Non-Mendelian Genetics

Multiple Choice

You have two flowers. The purple allele (P) is dominant over the white allele (p).

You breed a homozygous dominant flower (PP) with a homozygous recessive flower (pp).

What color will the offspring be?

• All purple

• All white

• All pink

• Half purple, half white.

Mendelian Genetics

Remember:​

Homo = same (TT ...tt ... RR ... aa)

Since homozygous is same, we have to clarify,

is it dominant (AA) or recessive (aa)

AA= homozygous dominant

aa= homozygous recessive

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Mendelian Genetics

Hetero = different (Tt ... Rr ... Aa)

Heterozygous means you inherited one of each allele.

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But heterozygous gives the same phenotype as homozygous dominant.

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​The only way to show

the recessive trait is to

have TWO recessive

alleles (bb)

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Non-Mendelian Genetics

Some traits don’t follow the simple dominant/recessive rules that Mendel first applied to genetics.

Traits can be controlled by more than one gene.

Some alleles are codominant.

Some alleles are neither dominant nor recessive.

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Multiple Choice

Red hair (R) and white hair (W) are codominant in cows.

Cross a white cow (WW) with a red cow (RR).

What color will the calves be?

• White

• Red

• Pink

• Roan

  (Mix of white spots and red spots)

Non-Mendelian Genetics

Codominance

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Two alleles are equally dominant and are both expressed in the phenotype.​

Ex: Coat color in cows

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RR: Red

WW: White

RW: Roan, white with red spots (NOT pink!)

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Multiple Choice

You have two flowers. The red allele shows incomplete dominance over the white allele.

You breed a red flower (RR) with a white flower (rr).

What do you think the offspring will look like?

• All red

• All white

• All pink

• Half red, half white.

Non-Mendelian Genetics

Incomplete Dominance​

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One allele is not completely

dominant over another.

The heterozygous phenotype is a

blending of the two homozygous phenotypes.

Example: four o’clock flowers

rr = red

ww = white

rw = pink (blending of the two alleles)

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Incomplete dominance vs. Codominance

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Incomplete dominance mixes like paint.

Red + White = pink (in between phenotype)

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Codominance mixes like marbles.​

Red + white = distinct patches of red and white (both phenotypes)

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Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have red flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have pink flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have white flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be red?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be white?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be roan?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple alleles and Codominance -

BLOOD TYPES

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Human blood has three alleles.

A and B are both codominant.

(I^A and I^B)

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o is recessive (i)

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Individuals can be type A, type B, type AB, or type O (recessive).

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Blood Groups

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​Type A:​

Homozygous: (AA) or (I^AI^A)

'

'

​Heterozygous: (Ao) or (I^Ai)

'

'

Can give blood to: A & AB

'

'

Can get blood from: A & O

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Blood Groups

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​​Type B:​

Homozygous: (BB) or (I^BI^B)

'

'

​Heterozygous: (Bo) or (I^Bi)

'

'

Can give blood to: B & AB

'

'

Can get blood from: B & O

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Blood Groups

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​​Type O:​

Homozygous recessive: (oo) or (ii)

'

'

​Can give blood to: A, B, AB, O

Universal donor

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'

Can get blood from: O

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Blood Groups

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​​Type AB:​

Heterozygous codominant:

(AB) or (I^AI^B)

'

'

​Can give blood to: AB

'

'

Can get blood from: A, B, AB, O

Universal receiver

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BLOOD TYPES

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People with blood group O are called "universal donors."

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People with blood group AB are called "universal receivers."

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If you have O blood hospitals will beg you to donate!

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BLOOD TYPE Reference

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​Type A:​

(I^AI^A) or (I^Ai) ; (AA) or (Ao)​

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Type B:

(I^BI^B) or (I^Bi) ; (BB) or (Bo)​

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Type AB:

(I^AI^B) ; (AB​)

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Type O:

(ii) ; (oo)

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​These two Punnett Squares are the same. They just use different ways of representing the A, B, and o alleles.

A mother with type O blood gives birth to a baby.

The father has type AB blood.

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What are some possible blood types that the baby could have?​

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____ x ____

father x mother

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Phenotypes:​

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​Type A:

Type B:​

​Type AB:

Type O:​

In 1968, a couple accused a hospital of switching their baby with another. DNA technology was unavailable so they used blood type to test if the baby was theirs or not.

Mom is type A and dad is type AB. The baby is type O blood.

Did the hospital make a mistake?

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​Phenotypes:​

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​Type A:

Type B:​

​Type AB:

Type O:​

BLOOD TYPE Reference

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​Type A:​

(I^AI^A) or (I^Ai) ; (AA) or (Ao)​

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Type B:

(I^BI^B) or (I^Bi) ; (BB) or (Bo)​

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Type AB:

(I^AI^B) ; (AB​)

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Type O:

(ii) ; (oo)

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​

​

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​These two Punnett Squares are the same. They just use different ways of representing the A, B, and o alleles.

In 1968, a couple accused a hospital of switching their baby with another. DNA technology was unavailable so they used blood type to test if the baby was theirs or not.

Mom is type A and dad is type AB. The baby is type O blood.

Did the hospital make a mistake?

​

​____ x _________

father x mother

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Phenotypes:​

​

​

​

​

​

​

​

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​Type A:

Type B:​

​Type AB:

Type O:​

A woman with type A blood has a child with type B blood. How is this possible?

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Start with what you know and fill that in!

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____ x ____

father x mother

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Phenotypes:​

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​Type A:

Type B:​

​Type AB:

Type O:​