Human Genetics

Identifying Human Phenotypes:

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Hitchhiker's Thumb Regular Thumb

                                                 

Examining Human Traits

• Complicating factors

Ambiguous phenotypes,

multiple alleles, major

and minor genes, turn

off genes, penetrance,

expressivity• Environment

important factor

KeyMale

Female

AffectedmaleAffectedfemale

Mating

Offspring, inbirth order(first-born on left)

Pedigree – Family history to show the transfer of genetic traits

Genetic disorders

Pedigree : Chart used to trace family histories of genetic traits

Pedigree

Hemophilia Family Tree

Karyotyping

Karyotyping

Down’s Syndrome

Autosomal Dominant Traits

ACHOO Syndrome

• Sneezing in

bright light

Dwarf

Dwarf D d

D DD Dd

Lethal Dwarf

d Dd dd

Dwarf Normal height

X

• Dwarfism – Homozygous

lethal

Sickle Cell Anemia

Blood disease –

99% Black population

Codominant trait

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• Bitter chemical taste• Phenylthiocarbamide

Polydactyly - extra finger or toe

Autosomal Recessive Traits

Albinism – (7 kinds in humans)

PKUPhenylketonuria

• Lack enzyme to metabolize phenylalanine. Mental retardation without treatment.

• N. European descent

PKU - 1 in 15,000 Americans.

• A non-food source of phenylalanine is the artificial sweetener Aspartame. This compound, sold under the trade names "Equal" and "NutraSweet", is metabolized by the body into several chemical byproducts including phenylalanine.

Cystic Fibrosis

• Prevents normal breathing and digestion.

• White americans

Tay-Sachs Disease

• Nervous system deterioration.

• European Jews

Porphyria

• Port wine urine disease

• Iron abnormality• George III – American

Independence, Mary Queen of Scots

• Rare form – eastern Europe

• Long fine hair all over body, dying necrotic tissue, eyes sensitive to light, gums destroyed, teeth with iron deposits

Porphyry ?

Sex-linked RecessiveColorblindness

Sex-linked Recessive Hemophilia