Non-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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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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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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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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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 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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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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​Type A:​

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

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​Heterozygous: (Ao) or (I^Ai)

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Can give blood to: A & AB

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Can get blood from: A & O

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​​Type B:​

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

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​Heterozygous: (Bo) or (I^Bi)

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Can give blood to: B & AB

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Can get blood from: B & O

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​​Type O:​

Homozygous recessive: (oo) or (ii)

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​Can give blood to: A, B, AB, O

Universal donor

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Can get blood from: O

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​​Type AB:​

Heterozygous codominant:

(AB) or (I^AI^B)

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​Can give blood to: AB

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

Universal receiver

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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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​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:​

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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.

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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​____ 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:​