1. Wed: Genetics Test & NOTEBOOK GRADE Bellwork: Mon. Jan. 30, 2017
1.This diagram is a ______________
2. This chromosomal error
(in pair 23) is called
___________________
3. What do we call this
process? (in pair 23)
Is this cat male or female?
How do you know?
What is this process called?
Wed: Genetics Test &
NOTEBOOK GRADE
From Calico Cat short video:

2. Bellwork: Tues. Jan. 31, 2017
Remember: in fruit flies, eye color is a sex linked
trait. r = white eyes, R = red eyes. A male fruit fly only has to have one recessive gene to have the trait.
Write the sex (m/f) and eye color (r/w) of the following:
1.XR Xr __,__ XR Y __,__ Xr Xr __,__XR XR __,__ Xr Y __,__
Write the genotypes of these flies: hint use: X?X? or X?Y:
2. white eyed, male ________, heterozygous red eyed female ________
white eyed, female ___________, red eyed, male ___________
3. Cross a red eyed female a red-eyed male:
the Cross: ______ x ______
Genotypic Ratio:
Phenotypic Ratio: f r

3. Calico Cats and Nondisjunction

4. X-Chromosome Inactivation
Females have two X chromosomes
Males have only one
If just one X chromosome is enough for cells in males, how does the cell “adjust” to the extra X chromosome in female cells?
British geneticist Mary Lyon discovered that in female cells, one X chromosome is randomly switched off. That turned-off chromosome forms a dense region in the nucleus known as a Barr body. Barr bodies are generally not found in males because their single X chromosome is still active.

5. The same process happens in other mammals
The same process happens in other mammals. In cats, for example, a gene that controls the color of coat spots is located on the X chromosome.
One X chromosome may have an allele for orange spots and the other may have an allele for black spots. In cells in some parts of the body, one X chromosome is switched off. In other parts of the body, the other X chromosome is switched off.

6. As a result, the cat's fur will have a mixture of orange and black spots, as shown in the figure below. Male cats, which have just one X chromosome, can have spots of only one color. By the way, this is one way to tell the sex of a cat. If the cat's fur has three colors—white with orange and black spots, for example—you can almost be certain that it is female.

9. Is this cat male or female?
How do you know?
What is this process called?

10. I’ll start the Evolution Biodiversity notes!!!
Work on your reviews or
I’ll start the Evolution Biodiversity notes!!!