For each of these conditions, mutant allele is dominant Powerpoints/chapter… · For each of these...
Transcript of For each of these conditions, mutant allele is dominant Powerpoints/chapter… · For each of these...
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson LearningFor each of these conditions, mutant allele is dominant over wild type allele
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Marfan Syndrome Is an AutosomalDominant Trait
• Affects skeletal system,eyes, and cardiovascularsystem
• Characteristics – tall, thinarms and legs with long,thin fingers and toes
• Weakened aorta mayenlarge and rupture
Fig. 4.13
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Marfan Syndrome May Affect the Aorta
Gene is located on chromosome 15 = fibrillinFig. 4.14
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Consanguineous mating
Huntington’sRare dominant trait
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Pedigree - Woody Guthrie
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Huntington’s disease-affected brains
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Nancy Wexler
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
The number of CAG repeats in huntingtin gene (htt)is directly correlated with probability of disease
polyQ (glutamine)
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
http://www.birf.info/art/people/media-stories/nd5.gif
Pathology of Huntington’s disease
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson LearningFigure 4.16
Pedigree 1 Pedigree 2
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Examples of Patterns of Inheritance
• Autosomal Recessive
• Autosomal Dominant
• X-Linked Dominant
• X-Linked Recessive
• Y-Linked Inheritance
• Mitochondrial Inheritance
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Transmission of X and Y Chromosomes
Fig. 4.16
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
X and Y Chromosomes
• Females carry two copies of the Xchromosome and may be homozygous orheterozygous for a given trait
• Males carry only one X chromosome andare hemizygous for all genes on the Xchromosome
• A male receives his Y chromosome fromhis father and his X from his mother
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
X-linked Dominant Traits
• Affected males produce all affecteddaughters but no affected sons
• (Criss-cross inheritance)
• Heterozygous females will have unaffectedand affected offspring; sons anddaughters will be equally affected
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
HypophosphatemiaIs an X-linked Dominant Trait
Fig. 4.17
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
X-Linked Recessive
• Hemizygous males and homozygousfemales are affected
• Males are more likely to be affected• Affected males receive the allele from
their mothers• Daughters must receive the allele from
both parents
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Pedigree for X-Linked Recessive Trait
Fig. 4.18
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Colorblindness
• Most common form of color blindness isred-green blindness
• 8% male population of US• Red blindness – unable to see red as a
distinct color• Green blindness – cannot see green or
other colors in the middle of the visualspectrum
• Rare form is an autosomal dominant traiton chromosome 7- blue blindness
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Ishihara plate test for colorblindness
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Defects in the ConesCause Color Blindness
Fig. 4. 21
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
http://home.comcast.net/~john.kimball1/BiologyPages/R/Red-greenGenes.gif
Red-green opsin genes
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Muscular Dystrophy
•Progressive weakness and loss of muscletissue
•Autosomal and X-linked forms
•Most common form is an X-linkedrecessive Duchenne musculardystrophy
•1/3500 males in U.S.
•Disease progresses rapidly
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Duchenne Muscular Dystrophy
• Gene located near end of Xchromosome
• Encodes for dystrophin
• Stabilizes cell membraneduring the stress of musclecontraction
• Several mutations withvariation in phenotype
• Characteristic movementsFig 4.22
Chapter 4 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning
Hemophilia and History