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Barr Bodies and Blood Types

Barr Bodies

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X-inactivation in female

 In females, one of the two X chromosomes in each somatic (body) cell becomes inactive during

 Why? ◦ Cells of females and males would have same effective dose of on the

 Inactive X chromosomes called Barr bodies

BARR BODY

 Found in females

 One X chromosome in each cell is randomly inactivated

 Inactivated X chromosome seen as a darkly staining area in the nucleus of a cell

 How many active chromosomes are found in the cells of a female?

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Barr Body

Do you see the Barr body?

Barr Bodies in Cats

 Calico cat ◦ Generally all females ◦ One of several genes controlling fur color found on X chromosome ◦ on X chromosome codes for either orange or black color ◦ Color pattern determined by random inactivation (Barr body)

Why do you think Calico Cats are usually all female?

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Ex: Tortoiseshell (Calico) cats

 animation

Calico Cat Color Inheritance

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Calico Cat

 There have been instances of male Calico cats found ◦ How could this happen? ◦ HINT: Male calico cats are sterile

Example in  Anhidrotic ectodermal dysplasia ◦ X linked mutation prevents the development of sweat glands

◦ A woman who is heterozygous will have patches of normal skin and patches of skin without sweat glands

◦ Difficulty controlling body temperature

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Blood Types

ABO BLOOD TYPES

 Example of codominance  Blood type depends on the presence or absence of certain carbohydrates (antigens) on surface of red blood cells  3 alleles are possible: ◦ IA :Type A Blood ◦ IB :Type B Blood ◦ i :Type O Blood

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ABO BLOOD TYPES

 IA and IB are codominant to each other when they are paired.

 i allele is recessive to both IA and IB

If mom is homozygous for type A blood and dad is Homozygous for Type B blood, all of the offspring will have what blood Type?

Which blood type has no antigens? Which blood type has both antigens? Which blood type accepts all the other blood types?

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ABO Blood Types

 Why is it important to get the right blood type when getting a transfusion?

◦ Transfusion Reactions  Immune system (antibodies) will attack cells that have an antigen that the body doesn’t recognize as “self”

ABO Blood Types

Which square shows type O blood?

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ABO Blood Types  Blood typing is actually far more complicated than“A”,“B”, and“O”

 ABO are the MAJOR antigens

 There are also MINOR antigens ◦ Rh factor: “+” or “-”

Rhesus macaque

ABO Blood Types

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ABO Blood Types

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