Epistasis Lesson

Epistasis Lesson

Learning Targets

• I can explain the difference between epistasis dominant and epistasis recessive.

• I can identify the 'appearance' of epistasis genotypes.

• I can use punnett squares to predict the ratio of crosses involving epistasis dom/rec.

Before you begin...

Please have notebook paper, blank 16 box page, green allele sheet available.

Multiple Choice

______ is the genetic occurrence in which two genes interact. One gene may 'suppress' another gene.

• Epigenetics

• Epistasis

• Genomics

• Trasnsmutations

Multiple Select

Based on the introduction...this video is going to focus on..

• Labrador Retrievers Coloration

• Squash Coloration

• Gerbils Coloration

• Hamster Coloration

• Zucchini Coloration

I might add...

Epistasis can also be thought of how one gene can 'turn off' another gene. We will learn how an epistasis gene can turn off the coloration gene that may be present in labs and squash plants. This causes labs to look yellow or squash to be white colored fruits.

Multiple Choice

Based on the presentation SQUASH, the epistasis gene is _________.

• Dominant

• Recessive

Multiple Select

So...B = Coloration Masked (white), b = Coloration gene 'unmasked'. A = Yellow and a = green coloration. Which genotypes below would be WHITE in coloration?

• aaBb

• AaBB

• aabb

• AAbb

• Aabb

Since the 'B' gene masks the yellow/green gene, then...

aaBb and AaBB would BOTH be WHITE squash plants. The "B" turns off the coloration gene.

Multiple Select

So...B = Coloration Masked (white), b = Coloration gene 'unmasked'. A = Yellow and a = green coloration. Which genotypes below would be YELLOW in coloration?

• aaBb

• aabb

• AaBB

• AAbb

• Aabb

Multiple Select

So...B = Coloration Masked (white), b = Coloration gene 'unmasked'. A = Yellow and a = green coloration. Which genotype(s) below would be GREEN in coloration?

• aaBb

• aabb

• AaBB

• AAbb

• Aabb

Multiple Choice

What is the color of the two parents? bbAa x BbAa

B = masking

b = No masking

A = yellow

a = green

• Yellow x White

• Yellow x Yellow

• White x Yellow

• Yellow x green

• green x yellow

Multiple Choice

What will be the ration of WHITE: YELLOW: GREEN offspring?

• 8 W: 6 Y: 2 G

• 8 W: 2 Y: 6 G

• 8 W: 4 Y: 4 G

• 6 W: 6Y: 4 G

• Some other ratio

How Mr. Ackert worked this one!.

Here is my answer key to the previous. 8 White, 6 Yellow and 2 White

Poll

Do you feel you understand the concept of Epistasis DOMINANT?

• Yes, Iḿ ready to move on.

• No, I need a bit of help.

If you need help...

Please ask Mr. Ackert before you move onto the next section. Thanks!

Please write these down:

E = Masking - OFF

e = Masking - ON (Yellow Coat)

B = Black coat

b = Chocolate Coat (brown)

Also know...the epistasis gene (ee) will NOT mask the nose and paw pad coloration.

Multiple Choice

A lab with the genotype of:

EeBb

would have a phenotype of...

• Black fur / Black nose

• Black fur / Chocolate nose

• Yellow Fur / Black nose

• Yellow Fur / Chocolate nose

• Yellow fur / yellow nose

Multiple Choice

A lab with the genotype of:

eeBb

would have a phenotype of...

• Black fur / Black nose

• Black fur / Chocolate nose

• Yellow Fur / Black nose

• Yellow Fur / Chocolate nose

• Yellow fur / yellow nose

Multiple Choice

A lab with the genotype of:

eebb

would have a phenotype of...

• Black fur / Black nose

• Black fur / Chocolate nose

• Yellow Fur / Black nose

• Yellow Fur / Chocolate nose

• Yellow fur / yellow nose

Multiple Choice

A lab with the genotype of:

Eebb

would have a phenotype of...

• Black fur / Black nose

• Chocolate fur / Chocolate nose

• Yellow Fur / Black nose

• Yellow Fur / Chocolate nose

• Yellow fur / yellow nose

Multiple Select

Which of these could be sold as a PUREBRED Labrador retrievers?

• eebb

• eeBB

• EeBB

• EEbb

• eeBb

A dog MUST be homozygous for both epistasis AND coloration

EEBB, EEbb, eeBB, eebb

Multiple Select

Which of these describe the two parents dogs of this cross?

• Black Lab / Black Nose

• Chocolate Lab / Chocolate Nose

• Yellow Lab / Black Nose

• Yellow Lab / Chocolate Nose

• Both Dogs are yellow labs

Here is my completed Punnett square

Poll

How well do you feel you now understand how to do the Epistasis recessive traits?

• I understand.

• I really don understand, but I am going to ask Mr. Ackert for help.

Please do a screen capture of your results following your completion of this video lesson.

Thanks! Mr. A