14-1 Human Heredity

Human Chromosomes

Karyotype = picture or pattern of chromosomes arranged in homologous pairs & organized by size (See fig. 14-1 p. 341)

Humans have 46 chromosomes

2 of these are sex chromosomes
XX = female XY = male

The other 44 chromosomes are known as autosomes

Human Traits

To study inheritance, biologists use pedigree charts

Shows relationships within a family

Pedigree studies are often used to track genetic disorders in a family.

Many traits are strongly influenced by environmental factors (ex: height,personality). The degree to which traits depend on genetics is called HERITABILITY

Human genome

Our complete set of genetic info , Includes tens of thousands of genes

Genes are mapped to chromosomes.

Used to determine how traits or diseases are inherited.

Example: BRCA1 is located on chromosome 17, it is associated with risk of breast cancer.

ABO Blood Group

Controlled by 3 alleles - A, B, O

A and B are codominant
O is recessive to both A and B
The blood type is the phenotype

Blood Type	Genotype	Can Donate to...	Can Receive from...
	AA, AO	A or AB	A or O
	BB, BO	B or AB	B or O
	AB	AB only	A or B or AB (universal receiver)
	OO	A, B, AB, O (universal donor)	Only O

Human Genetic Disorders

Recessive

Phenylketonuria (PKU)

Tay - Sachs disease recessive

Albinism

Cystic Fibrosis

Dominant

Achondroplasia

Huntington's disease

Polydactyly

Codominant

Sickle-cell disease

*Also gives resistance to malaria

Blood types (A and B are codominant)