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Chapter 12Chapter 12Inheritance Patterns Inheritance Patterns and Human Geneticsand Human Genetics

12.1 Objectives12.1 Objectives

Distinguish between sex Distinguish between sex chromosomes and autosomes.chromosomes and autosomes.

Explain the role of sex chromosomes.Explain the role of sex chromosomes. Know the difference between Know the difference between

chromosome mutations and gene chromosome mutations and gene mutations.mutations.

I. ChromosomesI. Chromosomes

A.A. What is a Chromosome?What is a Chromosome?A.A. A vehicle of genetic informationA vehicle of genetic information

B.B. Sex ChromosomesSex ChromosomesA.A. Determine the sex of organismsDetermine the sex of organisms

B.B. XX = femaleXX = female

C.C. XY = maleXY = male

D.D. Information on these chromosomes Information on these chromosomes gives the organism the sex specific gives the organism the sex specific characteristics.characteristics.

C. AutosomesC. Autosomes

1. the remaining chromosomes1. the remaining chromosomes

2. 22 pairs 2. 22 pairs

II. Chromosome MutationsII. Chromosome Mutations

A.A. Chromosome DeletionChromosome DeletionA.A. Loss of a piece of chromosomeLoss of a piece of chromosome

B.B. Chromosome inversionChromosome inversionA.A. Chromosome breaks off; flips and reattachesChromosome breaks off; flips and reattaches

C.C. Chromosome translocationChromosome translocationA.A. One chromosome breaks and reattaches to One chromosome breaks and reattaches to

anotheranother

D.D. NondisjunctionNondisjunctionA.A. Chromosomes fail to separate correctly Chromosomes fail to separate correctly

resulting in an extra copy.resulting in an extra copy.

III. Diseases from Chromosome III. Diseases from Chromosome MutationsMutations

A.A. Down Syndrome (Trisomy 21)Down Syndrome (Trisomy 21)A.A. Extra copy of chromosome #21Extra copy of chromosome #21

B.B. Distinct facial featuresDistinct facial features

C.C. Heart defectsHeart defects

D.D. Shorter lifespanShorter lifespan

E.E. Early AlzheimersEarly Alzheimers

F.F. Some degree of mental retardationSome degree of mental retardation

B. Turner’s SyndromeB. Turner’s SyndromeA.A. Only have 1 X chromosome; no other X or Only have 1 X chromosome; no other X or

YY

B.B. Genetically femaleGenetically female

C.C. Do not mature sexually; are sterileDo not mature sexually; are sterile

D.D. Short statureShort stature

E.E. Normal intelligenceNormal intelligence

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

D. Patau Syndrome (Trisomy 13)D. Patau Syndrome (Trisomy 13)A.A. serious eye, brain, and circulatory defectsserious eye, brain, and circulatory defects

B.B. Clef palateClef palate

C.C. Children only live a few monthsChildren only live a few months

Cleft PalateCleft Palate

Cleft PalateCleft Palate

E. Edward’s SyndromeE. Edward’s SyndromeA.A. Trisomy 18Trisomy 18

B.B. Most children only live a few monthsMost children only live a few months

C.C. All major organs affectedAll major organs affected

Sex Linked InheritanceSex Linked Inheritance

Gene for disease is found on X Gene for disease is found on X chromosome.chromosome.

Usually recessive.Usually recessive. Affects less females.Affects less females.

– Females may have the recessive gene but it Females may have the recessive gene but it can be covered up by the normal dominant can be covered up by the normal dominant gene on the 2gene on the 2ndnd X chromosome X chromosome

Affects more malesAffects more males– Since males only have 1 X chromosome, the Since males only have 1 X chromosome, the

recessive gene will be expressed if present.recessive gene will be expressed if present.

RedRed//GreenGreen Colorblindness Colorblindness

The gene which allows us to The gene which allows us to distinguish between red and green distinguish between red and green is on the X chromosome.is on the X chromosome.

= Female with normal visionXCXCXCXc

= Female carrier

XcXc= Female who is colorblind

RedRed//GreenGreen Colorblindness Colorblindness

The gene which allows us to The gene which allows us to distinguish between red and green distinguish between red and green is on the X chromosome.is on the X chromosome.

= Male with normal vision

= Male who is colorblind

XCYXcY

PedigreePedigree

XY

XY XY

XX

XX

Father Mother

Daughter

Son Son

Marriage

Children

Oldest Youngest

PEDIGREE CHARTSPEDIGREE CHARTS

A family history of a genetic A family history of a genetic conditioncondition

© 2007 Paul Billiet ODWS

What is a pedigree chart?What is a pedigree chart?

Pedigree charts show a record of the Pedigree charts show a record of the family of an individualfamily of an individual

They can be used to study the They can be used to study the transmission of a hereditary conditiontransmission of a hereditary condition

They are particularly useful when there They are particularly useful when there are large families and a good family are large families and a good family record over several generations.record over several generations.


Symbols used in pedigree Symbols used in pedigree chartscharts

Normal maleNormal male Affected maleAffected male Normal femaleNormal female Affected Affected

femalefemale MarriageMarriage

A marriage with five children, two daughters and three sons. The 2nd eldest son is affected by the condition.

Eldest child Youngest child


Organising the pedigree Organising the pedigree chartchart

– Generations are identified by Roman Generations are identified by Roman numeralsnumerals I

II

III

IV


Some HistorySome History

Hemophilia has played Hemophilia has played an important role in an important role in Europe's historyEurope's history

The disease began to The disease began to crop up in Great Britain's crop up in Great Britain's Queen Victoria’s Queen Victoria’s childrenchildren

It became known as the It became known as the "Royal disease" because "Royal disease" because it spread to the royal it spread to the royal families of Europe families of Europe through Victoria's through Victoria's descendants descendants

How it SpreadHow it Spread it spread through the it spread through the

Royal Houses of Royal Houses of Europe as monarchs Europe as monarchs arranged marriages arranged marriages to consolidate to consolidate political alliances. political alliances.

We can trace the We can trace the appearance of appearance of hemophilia as it hemophilia as it popped up in Spain, popped up in Spain, Russia, and Prussia Russia, and Prussia by looking at the by looking at the family tree. family tree.

The Royal Family TreeThe Royal Family Tree

Pedigree KaryotypePedigree Karyotype

Genetic DisordersGenetic Disorders

Huntington’s DiseaseHuntington’s Disease

Gradual brain deteriorationGradual brain deterioration Middle ageMiddle age Dominant trait found on chromosome Dominant trait found on chromosome

44 1 in 10,0001 in 10,000 Movie: Love and Other DrugsMovie: Love and Other Drugs

Cystic FibrosisCystic Fibrosis

Mucus clogs lungs and pancreasMucus clogs lungs and pancreas Use to cause early death now victims Use to cause early death now victims

can live to early adulthoodcan live to early adulthood Recessive gene on chromosome 7Recessive gene on chromosome 7 1 in 900 French Canadiens1 in 900 French Canadiens 1 in 2000 Europeans1 in 2000 Europeans

Sickle Cell AnemiaSickle Cell Anemia

Organ damage due to impaired blood Organ damage due to impaired blood flowflow

Recessive gene on chromosome 11Recessive gene on chromosome 11 1 in 500 African Americans1 in 500 African Americans

Tay Sachs DiseaseTay Sachs Disease

Deterioration of nervous systemDeterioration of nervous system Waste build up causes nerve cell Waste build up causes nerve cell

deathdeath Autosomal recessive gene on Autosomal recessive gene on

chromosome 15chromosome 15 1 in 600 Jews of European decent1 in 600 Jews of European decent

Marfan SyndromeMarfan Syndrome

Long limbsLong limbs Loose jointsLoose joints Deformed spineDeformed spine Crowded teethCrowded teeth Dominant gene on chromosome 15Dominant gene on chromosome 15 1 in 20000 Americans1 in 20000 Americans Abe LincolnAbe Lincoln

Breast Cancer (BRCA -1)Breast Cancer (BRCA -1)

Malignant tumors in breast tissueMalignant tumors in breast tissue Dominant gene on chromosome 17Dominant gene on chromosome 17 8% of breast cancer8% of breast cancer