Chapter 12 Inheritance Patterns and Human Genetics

12.1 Objectives Distinguish between sex chromosomes and autosomes. Explain the role of sex chromosomes. Know the difference between chromosome mutations and gene mutations.

I. Chromosomes What is a Chromosome? Sex Chromosomes A vehicle of genetic information Sex Chromosomes Determine the sex of organisms XX = female XY = male Information on these chromosomes gives the organism the sex specific characteristics.

C. Autosomes 1. the remaining chromosomes 2. 22 pairs

II. Chromosome Mutations Chromosome Deletion Loss of a piece of chromosome Chromosome inversion Chromosome breaks off; flips and reattaches Chromosome translocation One chromosome breaks and reattaches to another Nondisjunction Chromosomes fail to separate correctly resulting in an extra copy.

III. Diseases from Chromosome Mutations Down Syndrome (Trisomy 21) Extra copy of chromosome #21 Distinct facial features Heart defects Shorter lifespan Early Alzheimers Some degree of mental retardation

B. Turner’s Syndrome Only have 1 X chromosome; no other X or Y Genetically female Do not mature sexually; are sterile Short stature Normal intelligence

C. Klinefelter Syndrome A. males have an extra X chromosome (XXY) B. male sex organs C. may have feminine characteristics D. normal intelligence

D. Patau Syndrome (Trisomy 13) serious eye, brain, and circulatory defects Clef palate Children only live a few months

Cleft Palate

Cleft Palate

E. Edward’s Syndrome Trisomy 18 Most children only live a few months All major organs affected

Sex Linked Inheritance Gene for disease is found on X chromosome. Usually recessive. Affects less females. Females may have the recessive gene but it can be covered up by the normal dominant gene on the 2nd X chromosome Affects more males Since males only have 1 X chromosome, the recessive gene will be expressed if present.

Red/Green Colorblindness The gene which allows us to distinguish between red and green is on the X chromosome. X C = Female with normal vision X C c = Female carrier X c = Female who is colorblind

Red/Green Colorblindness The gene which allows us to distinguish between red and green is on the X chromosome. X C Y = Male with normal vision X c Y = Male who is colorblind

Pedigree XY XX XY XY XX Marriage Mother Father Children Daughter Son Oldest Youngest

A family history of a genetic condition PEDIGREE CHARTS A family history of a genetic condition © 2007 Paul Billiet ODWS

What is a pedigree chart? Pedigree charts show a record of the family of an individual They can be used to study the transmission of a hereditary condition They are particularly useful when there are large families and a good family record over several generations. © 2007 Paul Billiet ODWS

Symbols used in pedigree charts A marriage with five children, two daughters and three sons. The 2nd eldest son is affected by the condition. Eldest child  Youngest child Normal male Affected male Normal female Affected female Marriage © 2007 Paul Billiet ODWS

Organising the pedigree chart Generations are identified by Roman numerals I II III IV © 2007 Paul Billiet ODWS

Some History Hemophilia has played an important role in Europe's history The disease began to crop up in Great Britain's Queen Victoria’s children It became known as the "Royal disease" because it spread to the royal families of Europe through Victoria's descendants

How it Spread it spread through the Royal Houses of Europe as monarchs arranged marriages to consolidate political alliances. We can trace the appearance of hemophilia as it popped up in Spain, Russia, and Prussia by looking at the family tree.

The Royal Family Tree

Pedigree Karyotype

Genetic Disorders

Huntington’s Disease Gradual brain deterioration Middle age Dominant trait found on chromosome 4 1 in 10,000 Movie: Love and Other Drugs

Cystic Fibrosis Mucus clogs lungs and pancreas Use to cause early death now victims can live to early adulthood Recessive gene on chromosome 7 1 in 900 French Canadiens 1 in 2000 Europeans

Sickle Cell Anemia Organ damage due to impaired blood flow Recessive gene on chromosome 11 1 in 500 African Americans

Tay Sachs Disease Deterioration of nervous system Waste build up causes nerve cell death Autosomal recessive gene on chromosome 15 1 in 600 Jews of European decent

Marfan Syndrome Long limbs Loose joints Deformed spine Crowded teeth Dominant gene on chromosome 15 1 in 20000 Americans Abe Lincoln

Breast Cancer (BRCA -1) Malignant tumors in breast tissue Dominant gene on chromosome 17 8% of breast cancer