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.
© 2007 Paul Billiet ODWS
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
© 2007 Paul Billiet ODWS
Organising the pedigree Organising the pedigree chartchart
– Generations are identified by Roman Generations are identified by Roman numeralsnumerals I
II
III
IV
© 2007 Paul Billiet ODWS
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