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Chapter three test on Pedigrees and genetic disorders

What is a pedigree?

A graphic representation of genetic inheritance. A diagram made up of a set of symbols that identify males and females; individuals affected by the trait being studied; and family relationships

Affected female (image)

Affected male (image)

Male carrier (image)

Normal male (image)

Normal female (image)

Female carrier (image)

Give four examples of dominant heredity?

1) cleft chin
2) widow's peak
3) detached earlobes
4) hitchhikers thumb

Dead male (description)

Square with a line through it

Dead female (description)

Circle with a line through it

What is Huntington's disease?

A lethal genetic disorder caused by a rare dominant allele; It results in the breakdown of certain areas of the brain; normally deadly

What is incomplete dominance?

When the two alleles inherited from the parents are neither dominant nor recessive, but blend together to give a physical trait that is somewhere between the two

What is co-dominance?

The expression of both alleles

How are human blood types determined?

By the presence or absence of certain molecules on the surfaces of red blood cells

What are the three reasons blood type is important?

1) blood transfusions
2) paternity
3) transplants

What are sex-linked traits?

Traits controlled by genes located on the sex chromosomes

What defines a recessive pedigree?

When parents do not show the trait, but have children who do; a generation is skipped

What defines a dominant pedigree?

One or both parents show the trait; no generations are skipped

How do you know if a recessive pedigree is sex linked?

More males than females affected; Female carriers pass trait on to male sons

How do you know if a recessive pedigree is autosomal?

Roughly equal numbers of males and females are affected; female carriers pass trait on to BOTH sons and daughters equally

How do you know if a dominant pedigree is sex linked?

Male with trait passes the trait to ALL of his daughters

How do you know if a dominant pedigree is autosomal?

Male with trait DOES NOT pass the trait to all of his daughters

What are the 5 autosomal recessive disorders?

1) Albinism
2) Cystic Fibrosis
3) Galactosemia
4) Phenylketonuria
5) Tay-Sachs Disease

How many recessive alleles do you need to inherit to get these disorders? Albinism, Cystic Fibrosis, Galactosemia, Phenylketonuria, Tay-Sachs Disease)


What is Albinism?

Lack of pigment in skin, hair and eyes

What is Cystic Fibrosis?

Excess mucus in lungs, digestive tract and liver

What is Glactosemia?

Accumulation of galactose (a sugar) in tissues; mental retardation, eye and liver damage

What is Phenylketonuria?

Accumulation of phenylalanine in tissues; mental retardation; lacks enzyme that breaks down phenylalanine

What is Tay-Sachs Disease?

Lipid accumulation in brain cells; mental deficiency; blindness

What are three Autosomal dominant disorders?

1) Achondroplasia
2) Huntington's Disease
3) Hypercholesterolemia

What is Achondroplasia?


What is Huntington's Disease?

Mental retardation and uncontrollable movements; appears in middle age, leads to death

What is Hypercholesterolemia?

Excess cholesterol in blood; heart disease

How many dominant alleles do you need to inherit to get these disorders? (Achondroplasia, Huntington's Disease, Hypercholesterolemia)


What are the three sex linked recessive disorders?

1) Color Blindness
2) Hemophilia
3) Duchenne Muscular Dystrophy

What is Color Blindness

Unable to see certain colors

What is Hemophilia?

Excessive bleedings due to missing protein important for blood clotting

What is Duchenne Muscular Dystrophy?

Progressive weakening and loss of skeletal muscle - missing protein needed from proper muscle development

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