human genetics
DESCRIPTION
Human Genetics. Genetic abnormality = a genetic condition that is a deviation from the average: not life-threatening Genetic disorder = describes conditions that cause medical problems. Human Genetic Disorders. Karyotype. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/1.jpg)
Human GeneticsHuman Genetics
![Page 2: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/2.jpg)
• Genetic abnormalityGenetic abnormality = a genetic = a genetic condition that is a deviation from condition that is a deviation from the average: the average: notnot life-threatening life-threatening
• Genetic disorderGenetic disorder = describes = describes conditions that conditions that cause medical cause medical problemsproblems
Human Genetic DisordersHuman Genetic Disorders
![Page 3: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/3.jpg)
KaryotypeKaryotype• A A pictorial displaypictorial display of of metaphase metaphase
chromosomeschromosomes from a mitotic cell from a mitotic cell • Chromosomes are identified and arranged Chromosomes are identified and arranged
by their by their characteristic characteristic size, shape, size, shape, centromere centromere location and location and staining patternsstaining patterns
![Page 4: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/4.jpg)
Human KaryotypeHuman Karyotype
![Page 5: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/5.jpg)
Detects some Detects some fetal fetal abnormalities abnormalities through through karyotypingkaryotyping
Amnio-Amnio-centesiscentesis
![Page 6: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/6.jpg)
Human Chromosome Human Chromosome CharacteristicsCharacteristics
• Diploid set for Diploid set for humans humans = = 4646
• AutosomesAutosomes = = 2222
• Female-sex chromosomes = Female-sex chromosomes = homologous homologous (XX)(XX)
• Male-sex chromosomes = Male-sex chromosomes = non-homologous non-homologous (XY)(XY)
![Page 7: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/7.jpg)
• Either parent can Either parent can carry the carry the recessive allele on recessive allele on an autosome.an autosome.– HeterozygotesHeterozygotes
are symptom-are symptom-free.free.– HomozygotesHomozygotes
are are affectedaffected..
Autosomal RecessiveAutosomal Recessive
![Page 8: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/8.jpg)
• One defective or absent One defective or absent gene can result in the gene can result in the inability to make a inability to make a specific enzymespecific enzyme
• Recombinant DNA Recombinant DNA techniquestechniques may someday may someday correct faulty correct faulty chromosomeschromosomes
Genetic Errors of MetabolismGenetic Errors of Metabolism
Obesity gene discovered
![Page 9: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/9.jpg)
• GalactosemiaGalactosemia– Inability to metabolize lactoseInability to metabolize lactose
• Cystic FibrosisCystic Fibrosis– Inability to Inability to
breakdown breakdown mucous in lungs mucous in lungs and other organs and other organs
Genetic Errors of MetabolismGenetic Errors of Metabolism
![Page 10: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/10.jpg)
• Missing an enzyme Missing an enzyme to break down lipids, to break down lipids, leading to destruction leading to destruction of central nervous sys. of central nervous sys.
• Mainly found in Mainly found in Eastern European Eastern European JewishJewish decendents decendents 1:27 is a carrier1:27 is a carrier– Judaism is trying to eliminate gene Judaism is trying to eliminate gene
through non-breeding between through non-breeding between couples couples who are carrierswho are carriers
Tay-Sachs DiseaseTay-Sachs Disease
![Page 11: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/11.jpg)
• RecessiveRecessive, changes the shape of , changes the shape of the hemoglobin moleculethe hemoglobin molecule– ExtremelyExtremely painful, debilitating painful, debilitating
– Only distorts when Only distorts when deoxygenateddeoxygenated
Sickle-cell AnemiaSickle-cell Anemia
![Page 12: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/12.jpg)
• High frequency in High frequency in black populationsblack populations
• SS= no sickle-cellSS= no sickle-cell
• Ss = mild symptomSs = mild symptom
• ssss = full blown disease = full blown disease
Sickle-cell AnemiaSickle-cell Anemia
![Page 13: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/13.jpg)
Heterozygote SuperiorityHeterozygote Superiority• HeterozygotesHeterozygotes receive protection from receive protection from
symptoms of sickle-cell AND malaria - symptoms of sickle-cell AND malaria - advantage in malarial countriesadvantage in malarial countries
• SS + malaria = SS + malaria = malariamalaria only only
• Ss + malaria = Ss + malaria = no symptoms of eitherno symptoms of either
• ss + malaria = ss + malaria = mildmild sickle cell sickle cell
![Page 14: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/14.jpg)
• Sickle cells become trapped and destroyed Sickle cells become trapped and destroyed in the spleen causing in the spleen causing SplenicSplenic SequestionSequestion
• AnemiaAnemia
• Pain episodesPain episodes
• Stroke or Brain DamageStroke or Brain Damage
• Kidney failureKidney failure
• PneumoniaPneumonia
• Increased InfectionsIncreased Infections
ComplicationsComplications
![Page 15: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/15.jpg)
• Lack one enzyme to break Lack one enzyme to break down down phenylalaninephenylalanine– Products Products
accumulate, cause accumulate, cause mental retardation, mental retardation, other severe other severe symptomssymptoms– Treated through Treated through
dietary restrictionsdietary restrictions
PKUPKU
![Page 16: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/16.jpg)
• A dominant allele is A dominant allele is always always expressedexpressed and if it reduces the and if it reduces the chance of surviving or chance of surviving or reproducing, its frequency reproducing, its frequency should should decreasedecrease
• MutationsMutations and conditions that set and conditions that set in in late in lifelate in life work against this work against this
Autosomal DominantAutosomal Dominant
![Page 17: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/17.jpg)
• AchondroplasiaAchondroplasia ( (DwarfismDwarfism))–Lacks functional gene for somatropic Lacks functional gene for somatropic
hormone in the pituitaryhormone in the pituitary
Autosomal Autosomal DominantDominant
![Page 18: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/18.jpg)
• Acromegaly (Acromegaly (Gigantism)Gigantism)– Pituitary produces Pituitary produces
excess growth excess growth hormoneshormones
Errors in MetabolismErrors in Metabolism
![Page 19: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/19.jpg)
• A serious degeneration of the A serious degeneration of the nervous system with an onset from nervous system with an onset from age 40 onwardage 40 onward - Fatal, - Fatal, no cureno cure
• Gene has Gene has been been found found
Huntington’s DisorderHuntington’s Disorder
Woody Guthrie
Would Would you want you want to know?to know?
WHY???WHY???
![Page 20: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/20.jpg)
• Mutated gene Mutated gene occurs only on occurs only on the the XX chromosomechromosome
X-Linked RecessiveX-Linked Recessive
![Page 21: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/21.jpg)
• Heterozygous females are Heterozygous females are phenotypically normalphenotypically normal
• MalesMales are affected because are affected because they have only one they have only one allele for the trait (on the allele for the trait (on the X chromosome) and it X chromosome) and it can be recessive. can be recessive.
X-Linked RecessiveX-Linked Recessive
![Page 22: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/22.jpg)
• Color-blindnessColor-blindness
• BaldnessBaldness
X-Linked RecessiveX-Linked Recessive
![Page 23: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/23.jpg)
• Inability of blood to Inability of blood to clotclot because genes because genes do not code for clotting agent(s)do not code for clotting agent(s)
Hemophilia AHemophilia A
![Page 24: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/24.jpg)
Queen Victoria: a CarrierQueen Victoria: a Carrier
![Page 25: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/25.jpg)
• Afflicted persons need frequent Afflicted persons need frequent transfusionstransfusions and infusions of and infusions of artificial artificial clotting agentsclotting agents
• Internal bleedingInternal bleeding from falls or bruising from falls or bruising the most seriousthe most serious
• Cummulative scarring may Cummulative scarring may restrict movementrestrict movement
Hemophilia AHemophilia A
![Page 26: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/26.jpg)
• Similar to X-linked recessive alleles, Similar to X-linked recessive alleles, except the allele is also expressed in except the allele is also expressed in heterozygous femalesheterozygous females
• Examples: faulty Examples: faulty enamel (of the teeth) traitenamel (of the teeth) trait
X-Linked DominanceX-Linked Dominance
![Page 27: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/27.jpg)
• AneuploidyAneuploidy = one extra or one less = one extra or one less chromosome, may affect one of every chromosome, may affect one of every two newly fertilized eggstwo newly fertilized eggs
• PolyploidyPolyploidy = three or more of each = three or more of each chromosome, is common in plants but chromosome, is common in plants but is lethal to the zygote if it occurs in is lethal to the zygote if it occurs in humanshumans
Patterns of InheritancePatterns of Inheritance
![Page 28: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/28.jpg)
Meiotic ErrorsMeiotic Errors• NondisjunctionNondisjunction- - homologues don't homologues don't
separate in meiosis 1separate in meiosis 1
![Page 29: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/29.jpg)
• Homologues Homologues don't separate don't separate in meiosis 1in meiosis 1
Non-Non-disjunction disjunction
in Sex in Sex ChromosomesChromosomes
![Page 30: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/30.jpg)
Trisomy 21/Down SyndromeTrisomy 21/Down Syndrome
• Occurs more frequently Occurs more frequently in children born to in children born to older women older women andand men men
– 1 in 801 in 80 births after 40 yrs births after 40 yrs
– 1in 401in 40 births after 45 yrs births after 45 yrs
![Page 31: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/31.jpg)
• Most children show mental deficienciesMost children show mental deficiencies– Many lead productive livesMany lead productive lives
– 40% have heart defects40% have heart defects
– many have diabetes and many have diabetes and
have weight issueshave weight issues
Down SyndromeDown Syndrome
![Page 32: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/32.jpg)
![Page 33: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/33.jpg)
• XOXO– Females with only one X chromosome, Females with only one X chromosome,
mostly due to nondisjunction in mostly due to nondisjunction in fatherfather– Most are spontaneously abortedMost are spontaneously aborted– Sterile, short stature, Sterile, short stature,
heart defects, premature heart defects, premature aging, shorter livesaging, shorter lives
• YOYO = = LETHALLETHAL
Turner SyndromeTurner Syndrome
![Page 34: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/34.jpg)
• XXY XXY conditioncondition– Most from non-disjunction in mother Most from non-disjunction in mother
– Tall, some mental slownessTall, some mental slowness
– Poor male sex organ development; Poor male sex organ development; breast development; breast development;
usually sterileusually sterile
Klinefelter SyndromeKlinefelter Syndrome
![Page 35: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/35.jpg)
• XYYXYY condition condition• Fertile, tall, slight retardation, Fertile, tall, slight retardation,
increased strength & aggressionincreased strength & aggression • NOT predisposed to crime - a fallacyNOT predisposed to crime - a fallacy
Jacob SyndromeJacob Syndrome
![Page 36: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/36.jpg)
• TranslocationTranslocation– TransferTransfer of of
a a piece of piece of one one
chromosome chromosome
to anotherto another
Changes in Changes in Chromosome StructureChromosome Structure
![Page 37: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/37.jpg)
• DeletionsDeletions– Loss of a Loss of a
chromosome region chromosome region by by viral attack, viral attack, chemicals, chemicals, irradiation, or irradiation, or other other environmental environmental factorsfactors
Changes in Changes in Chromosome StructureChromosome Structure
![Page 38: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/38.jpg)
• DeletionDeletion or or translocationtranslocation of of material from 5th chromosomematerial from 5th chromosome–““Cry of the Cat”Cry of the Cat” (French) - sound (French) - sound
many children make many children make when cryingwhen crying
– Severe mental Severe mental retardation; internal retardation; internal problemsproblems
Cri-du-ChatCri-du-Chat
![Page 39: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/39.jpg)
• InversionInversion – Alters the position and sequence of Alters the position and sequence of
the genes so that gene order is the genes so that gene order is reversedreversed
Changes in Changes in Chromosome StructureChromosome Structure
![Page 40: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/40.jpg)
• DuplicationsDuplications– Occurs when a gene Occurs when a gene
sequence is sequence is in in excess excess of the normal of the normal amount.amount.
Changes in Changes in Chromosome StructureChromosome Structure
![Page 41: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/41.jpg)
• Fragile X syndromeFragile X syndrome
– Mental retardationMental retardation
– Repeats that may block Repeats that may block expression of gene on expression of gene on X chromosomeX chromosome
DuplicationsDuplications
![Page 42: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/42.jpg)
Mistake SummaryMistake Summary
![Page 43: Human Genetics](https://reader036.vdocuments.mx/reader036/viewer/2022062408/56813ca4550346895da651c0/html5/thumbnails/43.jpg)
DesignedDesignedbyby
Anne F. MabenAnne F. Maben
These images are forThese images are forviewing only and may notviewing only and may not
be published inbe published in
any formany form