14-1 Human Heredity Print Friendly and PDF

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...

Blood Type A

AA, AO A or AB A or O
Blood type B BB, BO B or AB B or O
Blood Type AB AB AB only

A or B or AB

(universal receiver)

Blood type O OO

A, B, AB, O

(universal donor)

Only O

Human Genetic Disorders

inheritance of recessive disease


Phenylketonuria (PKU)

Tay - Sachs disease recessive


Cystic Fibrosis



Huntington's disease



Sickle-cell disease

*Also gives resistance to malaria

Blood types (A and B are codominant)