Patterns of Heredity & Human Genetics

What is a pedigree?

Is a graphic representation of genetic inheritance.

Pedigree Info

• Shows genetic relationships Shows genetic relationships within a familywithin a family

• Square=male, circle femaleSquare=male, circle female• Horizontal line=reproductionHorizontal line=reproduction• Vertical line=connects Vertical line=connects

parents to offspringparents to offspring

Pedigree Chart for colorblindness

What is a karyotype?

• Shows picture of chromosomes Shows picture of chromosomes arranged in pairsarranged in pairs

• Contains SEX CHROMOSOMES (X and Contains SEX CHROMOSOMES (X and Y) and the rest (called AUTOSOMES)Y) and the rest (called AUTOSOMES)

What are some recessive heredity disorders and traits?

CYSTIC FIBROSISCYSTIC FIBROSIS

•Caused by RECESSIVE allelesCaused by RECESSIVE alleles•Excessive mucus in lungsExcessive mucus in lungs•Increased susceptibility to Increased susceptibility to infectioninfection

Other DisordersOther Disorders

Tay-Sachs Disease Recessive disorder

of the central nervous system

An enzyme is missing that breaks down a lipid produced and stored in the nervous system.

Phenylketonuria (PKU)

Recessive disorder that results from a missing enzyme that converts amino acid phenylalanine into tyrosine.

It damages the nervous system and to the brain.

One of the few we can prevent by knowing the baby is a carrier.

What are some dominant heredity disorders and traits?

Tongue RollingTongue Rolling

Widow’s PeakWidow’s Peak

Attached EarlobesAttached Earlobes

Hitchhiker ThumbHitchhiker Thumb

Chin FissureChin Fissure

FrecklesFreckles

PolydactylPolydactyl

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DimplesDimples

What is Genetics?What is Genetics?•The study of traits being passed The study of traits being passed from generation to generation.from generation to generation.

What is Codominance?What is Codominance?•When both alleles are expressed fully in When both alleles are expressed fully in phenotype phenotype

What is Incomplete What is Incomplete Dominance?Dominance?

•Alleles blend together, neither being Alleles blend together, neither being dominant dominant

Incomplete DominanceIncomplete Dominance

What are Multiple Alleles?What are Multiple Alleles?•More than two types of alleles for a traitMore than two types of alleles for a trait

Blood TypeBlood Type

Blood TypeBlood Type

•3 Alleles for antigens = 3 Alleles for antigens = IIAA, , IIBB, , and and ii

•IIAA and and IIB B are codominant, are codominant, ii is is recessiverecessive

What are Polygenic Traits?What are Polygenic Traits?•Many genes control traitsMany genes control traits

•Examples: height, skin colorExamples: height, skin color

What are Sex-linked Genes?What are Sex-linked Genes?•Genes located on the sex Genes located on the sex chromosomes, many on the “X”chromosomes, many on the “X”

Sex-linked TraitsSex-linked Traits•COLORBLINDNESSCOLORBLINDNESS

•Location = X chromosomeLocation = X chromosome

•Inability to distinguish different Inability to distinguish different colors, usually reds and greenscolors, usually reds and greens

Sex-linked TraitsSex-linked Traits

Sex-linked TraitsSex-linked Traits

Sex-linked TraitsSex-linked Traits•Why are males more likely to have Why are males more likely to have sex-linked traits?sex-linked traits?

•Colorblindness in males, 1 in 10, 1 Colorblindness in males, 1 in 10, 1 in 100 femalesin 100 females

•Males only have one X, so only Males only have one X, so only one recessive allele necessaryone recessive allele necessary

•Females, 2 X’s, so two recessives Females, 2 X’s, so two recessives necessary necessary