Chapter 12 Inheritance Patterns and Human Genetics

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

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

C. Autosomes 1. the remaining chromosomes pairs

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

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

B. Turner’s Syndrome B. Turner’s Syndrome A.Only have 1 X chromosome; no other X or Y B.Genetically female C.Do not mature sexually; are sterile D.Short stature E.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) A. serious eye, brain, and circulatory defects B. Clef palate C.Children only live a few months

Cleft Palate

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

Sex Linked Inheritance Gene for disease is found on X chromosome. Gene for disease is found on X chromosome. Usually recessive. Usually recessive. Affects less females. Affects less females. –Females may have the recessive gene but it can be covered up by the normal dominant gene on the 2 nd X chromosome Affects more males 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. The gene which allows us to distinguish between red and green is on the X chromosome. = Female with normal vision X C X C X C X c = Female carrier X c 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. The gene which allows us to distinguish between red and green is on the X chromosome. = Male with normal vision = Male who is colorblind X C Y X c Y

Pedigree XY XX Father Mother DaughterSon Marriage Children OldestYoungest

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

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

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

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

Some History Hemophilia has played an important role in Europe's 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 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 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. 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. 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 Pedigree Karyotype