KaryotypesKaryotypes

What are they?What are they?

A “picture” of a person’s 46 A “picture” of a person’s 46 chromosomes. chromosomes.

Chromosomes are arranged Chromosomes are arranged in homologous pairs.in homologous pairs.

Homologous pairs – Homologous pairs – chromosomes of the same chromosomes of the same size and shape, but are size and shape, but are notnot genetically idenitcal.genetically idenitcal.

Why use karyotypes?Why use karyotypes?

To determine sex:To determine sex: Male- XYMale- XY Female- XXFemale- XX

To see abnormalities in To see abnormalities in chromosomeschromosomes

Extra chromosomesExtra chromosomes Missing chromosomesMissing chromosomes Extra/missing pieces of Extra/missing pieces of chromosomeschromosomes

Normal KaryotypeNormal Karyotype

What’s the problem?What’s the problem?

Turner Syndrome Turner Syndrome 45, X0 – 45 45, X0 – 45

chromosomes, only chromosomes, only 1 X chromosome1 X chromosome

Sex: femaleSex: female Symptoms: Symptoms:

– Short stature Short stature – swelling of the hands swelling of the hands

and feet and feet – Low hairline Low hairline – Low-set ears Low-set ears – Reproductive Reproductive

sterility sterility

What’s the problem?What’s the problem?

Klinefelter's syndromeKlinefelter's syndrome

47, XXY47, XXY Sex: MaleSex: Male Symptoms:Symptoms:

– SterilitySterility– Youthful buildYouthful build– ““round body”round body”

What’s the problem?What’s the problem?

Down SyndromeDown Syndrome Trisomy 21 (three Trisomy 21 (three

copies of chromosome copies of chromosome #21)#21)

Symptoms:Symptoms:– head may be smaller head may be smaller

than normal & than normal & abnormally shaped. abnormally shaped.

– a flattened nosea flattened nose– protruding tongueprotruding tongue– upward slanting eyesupward slanting eyes– short hands and fingersshort hands and fingers

What’s the problem?What’s the problem?

Edward’s SyndromeEdward’s Syndrome

Trisomy 18 Trisomy 18 Symptoms:Symptoms:

– Failure to growFailure to grow– Low set, malformed Low set, malformed

earsears– Abnormalities in the Abnormalities in the

bones of the hands and bones of the hands and feetfeet

– Kidney and heart Kidney and heart defectsdefects

InterphaseInterphase

Cell duplicates DNACell duplicates DNA Individual Individual

chromosomes not yet chromosomes not yet visible.visible.

CANCERCANCER

What is it?What is it?

Uncontrolled cell division of Uncontrolled cell division of abnormal cells which may result in abnormal cells which may result in death.death.

MetastasisMetastasis: Cells from malignant : Cells from malignant tumors may break off and travel to tumors may break off and travel to other parts of the body, forming other parts of the body, forming new tumors.new tumors.

The Four The Four phasesphases of of MitosisMitosis

PMATPMAT

ProphaseProphase chromatin condenses

(chromosomes are now visible)

Chromosomes consist of two sister chromatids

nuclear membrane disappears

Centrosomes start to move to opposite ends (poles) of cell

spindles begin to form

MetaphaseMetaphase Spindles are fully

formed

chromosomes are attached to spindles at the centromeres

Chromosomes line up at the center (equator) of the cell

AnaphaseAnaphase

• Sister chromatids separate and move to opposite poles.

• Each chromatid is now considered an individual chromosome

TelophaseTelophase

2 nuclear envelopes reform

Chromosomes uncoil into chromatin

Spindles disappear

CytokensisCytokensis cytoplasm is divided in half

ANIMAL

PLANT

Animation of Mitosis