Human Heredity Chapter 14. Chromosomal Inheritance 2 Human Genetic Disorders Autosome - Any...
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Transcript of Human Heredity Chapter 14. Chromosomal Inheritance 2 Human Genetic Disorders Autosome - Any...
Human Heredity
Chapter 14
Chromosomal Chromosomal InheritanceInheritance 2
Human Genetic DisordersHuman Genetic Disorders
Autosome - Any chromosome other than a sex Autosome - Any chromosome other than a sex chromosomechromosome
Genetic disorders caused by genes on autosomes Genetic disorders caused by genes on autosomes are called autosomal disorders are called autosomal disorders Some genetic disorders are autosomal dominantSome genetic disorders are autosomal dominant An individual with AA has the disorderAn individual with AA has the disorder An individual with Aa has the disorderAn individual with Aa has the disorder An individual with aa does NOT have disorderAn individual with aa does NOT have disorder
Other genetic disorders are autosomal recessiveOther genetic disorders are autosomal recessive An individual with AA does NOT have disorderAn individual with AA does NOT have disorder An individual with Aa does NOT have disorder, but is a An individual with Aa does NOT have disorder, but is a
carriercarrier An individual with aa DOES have the disorderAn individual with aa DOES have the disorder
Chromosomal Chromosomal InheritanceInheritance 3
Autosomal Recessive Pedigree Autosomal Recessive Pedigree ChartChart
Chromosomal Chromosomal InheritanceInheritance 4
Autosomal Dominant Pedigree Autosomal Dominant Pedigree ChartChart
Chromosomal Chromosomal InheritanceInheritance 5
Autosomal Recessive DisordersAutosomal Recessive Disorders
Tay-Sachs DiseaseTay-Sachs Disease
Progressive deterioration of psychomotor Progressive deterioration of psychomotor functionsfunctions
Cystic FibrosisCystic Fibrosis
Mucus in bronchial tubes and pancreatic Mucus in bronchial tubes and pancreatic ducts is particularly thick and viscousducts is particularly thick and viscous
Phenylketonuria (PKU)Phenylketonuria (PKU)
Lack enzyme for normal metabolism of Lack enzyme for normal metabolism of phenylalaninephenylalanine
Chromosomal Chromosomal InheritanceInheritance 6
Cystic Fibrosis Cystic Fibrosis TherapyTherapy
Chromosomal Chromosomal InheritanceInheritance 7
Autosomal Dominant DisordersAutosomal Dominant Disorders
NeurofibromatosisNeurofibromatosis
Tan or dark spots develop on skin and darken Tan or dark spots develop on skin and darken
Small, benign tumors may arise from fibrous Small, benign tumors may arise from fibrous nerve coveringsnerve coverings
Huntington DiseaseHuntington Disease
Neurological disorderNeurological disorder
Progressive degeneration of brain cellsProgressive degeneration of brain cells
Severe muscle spasmsSevere muscle spasms
Personality disordersPersonality disorders
Chromosomal Chromosomal InheritanceInheritance 8
Autosomal Dominant DisordersAutosomal Dominant Disorders
NeurofibromatosisNeurofibromatosis
Tan or dark spots develop on skin and darken Tan or dark spots develop on skin and darken
Small, benign tumors may arise from fibrous Small, benign tumors may arise from fibrous nerve coveringsnerve coverings
Huntington DiseaseHuntington Disease
Neurological disorderNeurological disorder
Progressive degeneration of brain cellsProgressive degeneration of brain cells
Severe muscle spasmsSevere muscle spasms
Personality disordersPersonality disorders
Chromosomal Chromosomal InheritanceInheritance 9
A Victim of Huntington A Victim of Huntington DiseaseDisease
Chromosomal Chromosomal InheritanceInheritance 10
Huntington Disease:Huntington Disease:Normal and Diseased Normal and Diseased BrainBrain
Chromosomal Chromosomal InheritanceInheritance 11
Multiple Allelic Traits and CodominanceMultiple Allelic Traits and Codominance
Some traits controlled by multiple allelesSome traits controlled by multiple alleles
The gene exists in several allelic forms (but each individual The gene exists in several allelic forms (but each individual only has two)only has two)
ABO blood typesABO blood types
The alleles:The alleles: IIAA = A antigen on red cells, anti-B antibody in plasma = A antigen on red cells, anti-B antibody in plasma IIBB = B antigen on red cells, anti-AB antibody in plasma = B antigen on red cells, anti-AB antibody in plasma II = Neither A nor B antigens, both antibodies = Neither A nor B antigens, both antibodies
PhenotypePhenotype(Blood Type)(Blood Type) GenotypeGenotype
A (actually AA or AO)A (actually AA or AO) IIAAIIAA or I or IAAiiB (actually BB or BO)B (actually BB or BO) IIBBIIBB or I or IBBii
ABAB IIAAIIBB
O (actually OO)O (actually OO) iiii
Chromosomal Chromosomal InheritanceInheritance 12
Inheritance of Blood Inheritance of Blood TypeType
Chromosomal Chromosomal InheritanceInheritance 13Human X-Linked Disorders:Human X-Linked Disorders:
Red-Green Color BlindnessRed-Green Color Blindness
Color vision In humans:Color vision In humans:Depends three different classes of cone cells Depends three different classes of cone cells in the retinain the retina
Only one type of pigment is present in each Only one type of pigment is present in each class of cone cellclass of cone cell The gene for blue-sensitive is autosomalThe gene for blue-sensitive is autosomal The red-sensitive and green-sensitive genes are The red-sensitive and green-sensitive genes are on the X chromosomeon the X chromosomeMutations in X-linked genes cause RG color Mutations in X-linked genes cause RG color blindness:blindness: All males with mutation (XAll males with mutation (XbbY) are colorblindY) are colorblind Only homozygous mutant females (XOnly homozygous mutant females (XbbXXbb) are ) are
colorblindcolorblind Heterozygous females (XHeterozygous females (XBBXXbb) are asymptomatic ) are asymptomatic
carrierscarriers
Chromosomal Chromosomal InheritanceInheritance 14
X-Linked Recessive X-Linked Recessive PedigreePedigree
Chromosomal Chromosomal InheritanceInheritance
• What is a karyotype?What is a karyotype?
• What patterns of inheritance do human traits follow?What patterns of inheritance do human traits follow? Dominant and Recessive AllelesDominant and Recessive Alleles
Codominant and Multiple AllelesCodominant and Multiple Alleles
• How can pedigrees be used to analyze human inheritance?How can pedigrees be used to analyze human inheritance?
• How do small changes in DNA molecules affect human traits?How do small changes in DNA molecules affect human traits?
• What are the effects of errors in meiosis?What are the effects of errors in meiosis? nondisjunctionnondisjunction
15
Chromosomal Chromosomal InheritanceInheritance
http://www.dnalc.org/resources/3d/17-sickle-http://www.dnalc.org/resources/3d/17-sickle-cell.htmlcell.html
16
Chromosomal Chromosomal InheritanceInheritance
What is Sickle Cell Anemia?What is Sickle Cell Anemia?
A serious condition in which red A serious condition in which red blood cells can become sickle-blood cells can become sickle-shapedshaped
Normal red blood cells are smooth Normal red blood cells are smooth and round. They move easily through and round. They move easily through blood vessels to carry oxygen to all blood vessels to carry oxygen to all parts of the body.parts of the body.
Sickle-shaped cells don’t move easily Sickle-shaped cells don’t move easily through blood. They’re stiff and sticky through blood. They’re stiff and sticky and tend to form clumps and get and tend to form clumps and get stuck in blood vessels.stuck in blood vessels.
The clumps of sickle cell block blood The clumps of sickle cell block blood flow in the blood vessels that lead to flow in the blood vessels that lead to the limbs and organs. Blocked blood the limbs and organs. Blocked blood vessel can cause pain, serious vessel can cause pain, serious infection, and organ damage.infection, and organ damage.
Chromosomal Chromosomal InheritanceInheritanceNormal and Sickled Red Blood Cells Normal and Sickled Red Blood Cells
in Blood Vesselsin Blood Vessels
Figure A shows normal red blood cells flowing freely in a blood vessel. The inset image shows a cross-
section of a normal red blood cell with normal hemoglobin.
Figure B shows abnormal, sickled red blood cells clumping and blocking the blood flow in a blood
vessel. The inset image shows a cross-section of a sickled red blood cell with abnormal strands of
hemoglobin.
Source from http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_WhatIs.html
Chromosomal Chromosomal InheritanceInheritance
http://www.youtube.com/watch?http://www.youtube.com/watch?v=5n29ZCvtCI8v=5n29ZCvtCI8
What is cystic fibrosis (CF)?What is cystic fibrosis (CF)?
Chromosomal Chromosomal InheritanceInheritance
Cystic FibrosisCystic Fibrosis
Inherited monogenic disorder presenting as a Inherited monogenic disorder presenting as a multisystem disease.multisystem disease.
Typically presents in childhoodTypically presents in childhood
7% of CF patients diagnosed as adults7% of CF patients diagnosed as adults
Most common life limiting recessive trait Most common life limiting recessive trait among whitesamong whites
Chromosomal Chromosomal InheritanceInheritance
Cystic FibrosisCystic Fibrosis
Prognosis improvingPrognosis improving
>38% of CF patients are older than 18>38% of CF patients are older than 18
13% of CF patients are older than 3013% of CF patients are older than 30
Median survivalMedian survival
Males: 32 yearsMales: 32 years
Females: 29 yearsFemales: 29 years
22Nondisjunction
23Trisomy 21
Chromosomal Chromosomal InheritanceInheritance 24Chromosome Number:Chromosome Number:
Abnormal Sex Chromosome NumberAbnormal Sex Chromosome Number
Result of inheriting too many or too few X or Result of inheriting too many or too few X or Y chromosomesY chromosomes
Caused by nondisjunction during oogenesis Caused by nondisjunction during oogenesis or spermatogenesisor spermatogenesis
Turner Syndrome (XO)Turner Syndrome (XO)
Female with single X chromosomeFemale with single X chromosome
Short, with broad chest and widely spaced Short, with broad chest and widely spaced nipplesnipples
Can be of normal intelligence and function Can be of normal intelligence and function with hormone therapywith hormone therapy
Chromosomal Chromosomal InheritanceInheritance 25Chromosome Number:Chromosome Number:
Abnormal Sex Chromosome NumberAbnormal Sex Chromosome Number
Klinefelter Syndrome (XXY)Klinefelter Syndrome (XXY)
Male with underdeveloped testes and Male with underdeveloped testes and prostate; some breast overdevelopmentprostate; some breast overdevelopment
Long arms and legs; large handsLong arms and legs; large hands
Near normal intelligence unless XXXY, XXXXY, Near normal intelligence unless XXXY, XXXXY, etc.etc.
No matter how many X chromosomes, No matter how many X chromosomes, presence of Y renders individual malepresence of Y renders individual male
26Turner and Klinefelter Syndromes
Chromosomal Chromosomal InheritanceInheritance 27Chromosome Number:Chromosome Number:
Abnormal Sex Chromosome NumberAbnormal Sex Chromosome Number
Ploy-X femalesPloy-X females
XXX simply taller & thinner than usualXXX simply taller & thinner than usual
Some learning difficultiesSome learning difficulties
Many menstruate regularly and are fertileMany menstruate regularly and are fertile
More than 3 Xs renders severe mental More than 3 Xs renders severe mental retardationretardation
Jacob’s syndrome (XYY)Jacob’s syndrome (XYY)
Tall, persistent acne, speech & reading Tall, persistent acne, speech & reading problemsproblems
Chromosomal Chromosomal InheritanceInheritance 28
Abnormal Chromosome StructureAbnormal Chromosome Structure
DeletionDeletion
Missing segment of chromosomeMissing segment of chromosome
Lost during breakageLost during breakage
TranslocationTranslocation
A segment from one chromosome moves to a A segment from one chromosome moves to a non-homologous chromosomenon-homologous chromosome
Follows breakage of two nonhomologous Follows breakage of two nonhomologous chromosomes and improper re-assemblychromosomes and improper re-assembly