Human Inheritance

Chapter 14 sec. 1 and 2

Pedigree Analysis

Pedigree = a family record that shows how a trait is inherited over several generations

Pedigrees

Pattern of inheritance = use phenotype to determine possible genotype of family patterns

Carrier = carries recessive allele but does not show phenotype

Genetic Traits and Disorders

Genetic disorders = disease or condition that is due to genetic alterations

Single Allele Traits

Are controlled by one allele of a gene

More than 200 human traits

Huntington’s Disease

Dominant allele Humans in 30 or 40’s show forgetfulness,

irritability, muscle spasms, severe mental illness

Cystic Fibrosis

Single recessive trait

Multiple Allele traits

3 or more alleles Blood types (ABO)

Polygenic traits

2 or more genes Skin color = 3-6 genes (amount of melanin) Eye color = little melanin (blue) more (brown) Allows for degree of variation

X-linked traits

Colorblindness = recessive x linked (8% of males)

X linked traits

Hemophilia = recessive x linked (males) Blood doesn’t clot

Nondisjunction Disorders

Monosomy= 45 chromosomes (missing one)

Trisomy = 47 chromosome (extra one)

Down Syndrome

Extra chromosome on 21st pair (trisomy-21)

Klinefelter’s Syndrome

Males with extra X (XXY) Mental retardation, female characteristics,

and infertile

Turner’s Syndrome

Single X sex chromosome (XO) Female appearance, infertile

Detecting Disorders

Genetic screening = karyotype Genetic counseling

In Fetus

Amnocentesis Chronic villi sampling