Non-Mendelian Inheritance

​Unit 6A Pt4 -
Non-Mendelian Inheritance Patterns

HS-LS1-1: Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.

HS-LS3-1: Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.

Multiple Choice

Why do they call non-mendelian genetics patterns "rule breakers"?

• They use RNA not DNA

• Having a dominant allele doesn't necessarily mean that trait will show

• There are no dominant alleles, only recessive ones in these patterns

• They defy the laws of nature.

Multiple Choice

What happens in codominance?

• the dominant allele isn't completely expressed when the recessive one is present.

• both alleles are considered dominants, so both traits show up.

• more than one gene works together to determine a trait

• 1 gene depends on another to be expressed.

Multiple Choice

An example of a epistasis is ...

• Heterozygote snapdragons are pink, not red or white

• Heterozygote chickens are black AND white, not just one or the other

• The three alleles that affect height

• The gene that controls whether llama wool color will be expressed

GENETICS - EXAMPLES OF NON-MENDELIAN

INCOMPLETE DOMINANCE

CODOMINANCE

MULTIPLE ALLELES

EPISTASIS

POLYGENIC TRAITS

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.

​

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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Non-Mendelian Genetics
Incomplete Dominance​

​

One allele is not completely

dominant over another.

The heterozygous phenotype is an

intermediate form of the two homozygous phenotypes.

Example: Four o’ Clock Flowers

rr = red ww = white rw = pink
Example: 'Blue' Chicken
CB = black CW = white CBCW = 'blue'

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Multiple Choice

When red snapdragons are crossed with white snapdragons, the offspring produce pink flowers. This is an example of:

• complete dominance

• incomplete dominance

• codominance

• polygenic inheritance

• multiple alleles

Multiple Choice

If a dark brown horse and a white horse are bred, the offspring are palomino (tan). This is an example of:

• complete dominance

• incomplete dominance

• codominance

• polygenic inheritance

• multiple alleles

Multiple Select

Which of the following alleles is recessive?

• I^A

• I^B

• I^A and I^B

• i

Multiple Choice

Which of the following alleles are codominant?

• I^A and i

• I^B and i

• I^A and I^B

• i

Non-Mendelian Genetics

Codominance

​

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

Ex: Coat color in cows & Checkered feathers in chickens

​

RR: Red

WW: White

RW: Roan, white with red spots

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Incomplete dominance vs. Codominance

​

Incomplete dominance mixes like paint.

Red + White = pink (in between phenotype)

​

Codominance mixes like marbles.​

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

​

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Multiple Choice

What type of inheritance pattern does the diagram represent?

• Incomplete Dominance

• Codominance

• Multiple Alleles

• Polygenic Inheritance

Multiple Choice

This flower is produced by crossing a pink-flowering plant and a white-flowering plant. This is an example of:

• complete dominance

• incomplete dominance

• codominance

• polygenic inheritance

• multiple alleles

Multiple Choice

When red cows are crossed with white cow, the offspring have a mix of red hair and white hair. These cows are called roan. This is an example of:

• complete dominance

• incomplete dominance

• codominance

• polygenic inheritance

• multiple alleles

Multiple alleles and Codominance -

BLOOD TYPES

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Two alleles are equally dominant and are both expressed in the phenotype.​
Human blood has three alleles.

A and B are both codominant.

(I^A and I^B) and o is recessive (i)

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

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Multiple Choice

The gene for human blood type has three alleles, A, B and O. This is an example of:

• complete dominance

• incomplete dominance

• codominance

• polygenic inheritance

• multiple alleles

​Universal Donor

• Can donate to all types

• can only receive from type O

Type O

​Universal Receiver

• Can receive blood from all types

​​Type AB

Multiple Choice

What is NOT a possible genotype for someone with type B blood?

• I^BI^B
• I^AI^B
• I^B i
• All of these are examples of type B blood

Match

Match the following

• I^AI^{A or} I^Ai

• ii or I^oI^o

• I^AI^B

• I^BI^B or I^Bi

Type A

Type O

Type AB

Type B

• Type A

• Type O

• Type AB

• Type B

Multiple Choice

Which of the following is true about blood type O?

• It contains antigen A only.

• It contains antigen B only.

• It contains both antigen A and antigen B.

• It doesn’t contain antigen A or antigen B.

Multiple Choice

Checkered chickens have an allele for black feathers and an allele for white feathers. This is an example of:

• complete dominance

• incomplete dominance

• codominance

Multiple Choice

Mom was black. Dad was white. What is the most likely explanation?

• complete dominance

• incomplete dominance

• codominance

Multiple Choice

Mom and dad are star belly sneeches. Baby does not have a star. What is the best explanation for this?

• complete dominance

• incomplete dominance

• codominance

Multiple Choice

Mom was white. Dad was black. What is the most likely explanation for this?

• complete dominance

• incomplete dominance

• codominance

Multiple Choice

The color gene for labrador retriever comes in 2 alleles, black and brown. The black allele completely masks the brown allele. This is an example of:

• complete dominance

• incomplete dominance

• codominance

Match

Match the following

• ABO BLOOD

• BLUE CHICKEN

• ROAN COW

MULTIPLE ALLELE

INCOMPLETE DOMINANCE

CODOMINANCE

• MULTIPLE ALLELE

• INCOMPLETE DOMINANCE

• CODOMINANCE