Foothill High School Science Department

The Human Genome

Karyotypes, Pedigrees &Genetic Disorders

Foothill High School Science Department

Human Chromosomes

• KaryotypeKaryotype– Pictures of Chromosomes Arranged In Pictures of Chromosomes Arranged In

Homologous PairsHomologous Pairs• Homo sapiensHomo sapiens

– 46 Chromosomes46 Chromosomes• 23 from Mom23 from Mom• 23 from Dad23 from Dad

Foothill High School Science Department

Foothill High School Science Department

Human Chromosomes

• Sex ChromosomesSex Chromosomes– FemalesFemales XXXX– MalesMales XYXY

• AutosomesAutosomes– Remaining 44 ChromosomesRemaining 44 Chromosomes

Foothill High School Science Department

Key ConceptKey ConceptKey Concept::All egg cells All egg cells

single X single X Chromosome.Chromosome.

SpermSpermhalf carry Xhalf carry Xhalf carry Y half carry Y

chromosomes.chromosomes.

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Key Concept (cont.)

This insures that This insures that just just about half about half of the zygotes:of the zygotes:

XX XX (female)(female)

About half About half XY XY (male)(male)

Foothill High School Science Department

Pedigree ChartPedigree ChartShows Family Relationships and Occurrences Of Shows Family Relationships and Occurrences Of

Traits Linked To Single GenesTraits Linked To Single Genes

Foothill High School Science Department

Human Traits

• Single Gene TraitsSingle Gene Traits– Linked To ONE GeneLinked To ONE Gene

• Polygenic TraitsPolygenic Traits– Linked To Multiple GenesLinked To Multiple Genes– Shape of Eyes & EarsShape of Eyes & Ears– Skin ColorSkin Color

Foothill High School Science Department

Human Traits

Expression of Traits isExpression of Traits is::–Shaped By Environment, Shaped By Environment,

Nutrition, ExerciseNutrition, Exercise

Foothill High School Science Department

Foothill High School Science Department

From Gene To Molecule

Key ConceptKey Concept::In Both In Both Cystic FibrosisCystic Fibrosis & & Sickle Sickle

Cell DiseaseCell Disease, A Small Change In , A Small Change In The DNA Of A Single Gene The DNA Of A Single Gene Affects The Structure Of A Affects The Structure Of A Protein, Causing A Serious Protein, Causing A Serious Genetic DisorderGenetic Disorder

Foothill High School Science Department

Cystic Fibrosis

• FatalFatal• Mostly Among Those Of Northern Mostly Among Those Of Northern

European AncestryEuropean Ancestry• Recessive Allele – Chromosome 7Recessive Allele – Chromosome 7• Digestive ProblemsDigestive Problems• Heavy Mucus Lungs & BronchiolesHeavy Mucus Lungs & Bronchioles

Foothill High School Science Department

Cystic Fibrosis

• Abnormal Protein, Does NOT Allow Normal Flow Of Chloride Ions Through Cellular Membrane

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Cystic FibrosisCystic Fibrosis

LungNormalLung

Foothill High School Science Department

Sickle Cell Disease

• Usually Among Africans & African Usually Among Africans & African AmericansAmericans

• Abnormal Hemoglobin Causes Abnormal Hemoglobin Causes Misshapen Red Blood CellsMisshapen Red Blood Cells

• Caused By Change In Caused By Change In 1 DNA Base 1 DNA Base In In The Gene:The Gene:– Valine Replaces Glutamic AcidValine Replaces Glutamic Acid

Foothill High School Science Department

Sickle Cell Disease

• Red Cells Change Shape When Oxygen Red Cells Change Shape When Oxygen Levels Drop – Exacerbated By ColdLevels Drop – Exacerbated By Cold

• Protective Against Malaria Protective Against Malaria – Beneficial – Beneficial In West Central AfricaIn West Central Africa

Foothill High School Science Department

Sickle Cell DiseaseNormal

Peripheral

Smear

Sickle Cell

Disease

Peripheral

Smear

Foothill High School Science Department

Sickle Cell Disease

MalariaMalaria

Sickle Cell