Karyotypes and Sex-Karyotypes and Sex-Linked TraitsLinked Traits

Diagnose the karyotypes in the back of the room at your table. Make sure to include:

• Case number

• Boy or girl

• Number of chromosomes

• Normal or abnormal

(if abnormal, what is the problem?)

What is a karyotype?What is a karyotype? Picture of your Picture of your

chromosomeschromosomes Arranged from largest Arranged from largest

to smallestto smallest quickly identify quickly identify

chromosomal changeschromosomal changes http://http://

www.biology.arizona.ewww.biology.arizona.edu/human_Bio/du/human_Bio/activities/karyotyping/activities/karyotyping/karyotyping2.htmlkaryotyping2.html

Genetics Disorders Genetics Disorders and Mutationsand Mutations

Mutations …Mutations …

are changes in the are changes in the genetic materialgenetic material

can be good or badcan be good or bad can be on a single can be on a single

gene or the whole gene or the whole chromosomechromosome

Genetic DisorderGenetic Disorder – – abnormal condition that a person abnormal condition that a person

inherits through genes or inherits through genes or chromosomes. chromosomes.

They are caused by mutations or They are caused by mutations or changes in a person’s DNA.changes in a person’s DNA.

Write down 3 disorders that have affected someone you know.

Cystic FibrosisCystic Fibrosis Genetic disorder where the body produces abnormally thick Genetic disorder where the body produces abnormally thick

mucus in the lungs and intestines making respiration and mucus in the lungs and intestines making respiration and digestion difficultdigestion difficult

caused by a mutation in a gene. The product of this gene is caused by a mutation in a gene. The product of this gene is a chloride ion channel important in creating sweat, a chloride ion channel important in creating sweat, digestive juices and mucus. digestive juices and mucus.

One in four babies are born with cystic fibrosisOne in four babies are born with cystic fibrosis Most common among Northern European descentMost common among Northern European descent

Sickle Cell AnemiaSickle Cell Anemia Sickle cell is a genetic disorder that affects the Sickle cell is a genetic disorder that affects the

blood’s hemoglobin. Hemoglobin is the protein blood’s hemoglobin. Hemoglobin is the protein in your blood that carries oxygen.in your blood that carries oxygen.

Sickle-cell anemia is caused by a point mutation Sickle-cell anemia is caused by a point mutation in protein chain of hemoglobin, replacing the in protein chain of hemoglobin, replacing the amino acid glutamic acid with the amino acid amino acid glutamic acid with the amino acid valinevaline

The ‘sickle shape’ of the cell doesn’t allow the The ‘sickle shape’ of the cell doesn’t allow the red blood cell to carry very much oxygen.red blood cell to carry very much oxygen.

Most common among African American descentMost common among African American descentFamous People with Sickle Cell Disease

Miles Davis, jazz musician. Paul Williams, singer (The Temptations)

Georgeanna Tillman, singer (The Marvelettes) Tionne "T-Boz" Watkins, singer (TLC)

HemophiliaHemophilia Hemophilia is a genetic disorder in which a Hemophilia is a genetic disorder in which a

person’s blood clots VERY slowly or not at all. person’s blood clots VERY slowly or not at all. A person with hemophilia can bleed to death A person with hemophilia can bleed to death

from a paper cut or scrape. from a paper cut or scrape. This is sex-linked disorder on the X This is sex-linked disorder on the X

chromosome.chromosome.– Queen Elizabeth suffered from this disorder.Queen Elizabeth suffered from this disorder.

This man received a vaccine. This is what having hemophilia did to is body.

Down SyndromeDown Syndrome Down Syndrome is a genetic disorder Down Syndrome is a genetic disorder

that occurs when an individual receives that occurs when an individual receives an extra copy of a chromosome. an extra copy of a chromosome.

A mistake occurs during Meiosis I: the A mistake occurs during Meiosis I: the chromosomes failed to separate correctly chromosomes failed to separate correctly (non-disjunction) therefore leaving an (non-disjunction) therefore leaving an extra copy of chromosome #21. extra copy of chromosome #21.

Doctor’s use tools like Doctor’s use tools like amniocentesisamniocentesis and and karyotypeskaryotypes to to helphelp detect detect most diseases.most diseases.

4 Types of Genetic 4 Types of Genetic DisordersDisorders

1. Single gene1. Single gene – Change in the DNA sequenceChange in the DNA sequence– More than 6000 known disordersMore than 6000 known disorders– Autosomal or sex linkedAutosomal or sex linked– 1 in 200 births1 in 200 births

Examples:Examples: cystic fibrosis, sickle cell anemia, cystic fibrosis, sickle cell anemia,

Marfan syndrome, Huntington’s disease Marfan syndrome, Huntington’s disease

Types of Genetic DisordersTypes of Genetic Disorders

2. Multi-factoral2. Multi-factoral– combination of environmental factors combination of environmental factors

and mutations in multiple genes and mutations in multiple genes – more complicated more complicated

Examples:Examples:

heart disease, high blood pressure, heart disease, high blood pressure, Alzheimer’s disease, arthritis, diabetes, Alzheimer’s disease, arthritis, diabetes, cancer, and obesity cancer, and obesity

Types of Genetic DisordersTypes of Genetic Disorders

3. Chromosomal3. Chromosomal– abnormalities in chromosome structure abnormalities in chromosome structure

as missing or extra copies or gross as missing or extra copies or gross breaks and rejoining breaks and rejoining

Example:Example:

Down SyndromeDown Syndrome

Types of Genetic DisordersTypes of Genetic Disorders

4. Mitochondrial4. Mitochondrial– rare type of genetic disorder rare type of genetic disorder – caused by mutations in the non-caused by mutations in the non-

chromosomal DNA of mitochondria chromosomal DNA of mitochondria

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Here are some genetics disorders, some you have heard about and some you haven’t.

Turners SyndromeTurners Syndrome

1 in 5,000 births

45 chromosomesX only #23 MonosomyNondisjunction

Turners SyndromeTurners Syndrome

96-98% do not survive to birthNo menstruationNo breast developmentNo hipsBroad shoulders and neck

Cri-Du-Chat Cri-Du-Chat SyndromeSyndrome

1 in 216,000 births

46 chromosomesXY or XX

#5 Deletion of lower arm

Cri-Du-Chat SyndromeCri-Du-Chat Syndrome

Moon-shaped faceHeart diseaseMentally retardedMalformed larynxNormal lifespan

Aniridia-Wilms Tumor Aniridia-Wilms Tumor SyndromeSyndrome

1 in 50,000,000 births

46 chromosomesXY or XX

#11 Deletion of upper arm

Aniridia-Wilms Tumor SyndromeAniridia-Wilms Tumor Syndrome

Mentally retardedGrowth retardedBlindnessTumors on kidneysShort lifespan

Thirteen Q Deletion Thirteen Q Deletion SyndromeSyndrome

1 in 500,000 births

46 chromosomesXY or XX

#13 Deletion of lower arm

Thirteen Q Deletion SyndromeThirteen Q Deletion Syndrome

Mentally retardedDeformed faceNo thumbsHeart diseaseShort lifespan

Prader-Willi Prader-Willi SyndromeSyndrome

1 in 5,000,000 births

46 chromosomesXY=97% XX=3%

#15 Deletion of lower arm

Prader-Willi SyndromePrader-Willi Syndrome

Small bird-like headMentally retardedRespiratory problemsObesityShort lifespan

Eighteen Q Deletion Eighteen Q Deletion SyndromeSyndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#18 Deletion of lower arm

Eighteen Q Deletion SyndromeEighteen Q Deletion Syndrome

Mentally retardedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan

Cat-Eye SyndromeCat-Eye Syndrome

1 in 1,000,000 births

46 chromosomesXY or XX

#22 Deletion of bottom arm

Cat-Eye SyndromeCat-Eye Syndrome

Fused fingers and toesMentally retardedSmall jawHeart problemsNormal lifespan

Four-Ring SyndromeFour-Ring Syndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#4 Inversion

Four-Ring SyndromeFour-Ring Syndrome

Cleft palateClub feetTestes don’t descendShort lifespan

1 in 1,250 births

47 chromosomesXY or XX

#21 Trisomy Nondisjunction

Down Syndrome Trisomy

Down SyndromeDown Syndrome

Short, broad hands Stubby fingersRough skinImpotency in malesMentally retardedSmall round faceProtruding tongueShort lifespan

Patau’s Trisomy Patau’s Trisomy SyndromeSyndrome

1 in 14,000 births

47 chromosomesXY or XX

#13 Trisomy Nondisjunction

Patau’s Trisomy SyndromePatau’s Trisomy Syndrome

Small headSmall or missing eyesHeart defectsExtra fingersAbnormal genitaliaMentally retardedCleft palateMost die a few weeks after birth

Edward’s Trisomy Edward’s Trisomy SyndromeSyndrome

1 in 4,400 births

47 chromosomesXX=80%

XY=20%

#18 Trisomy Nondisjunction

Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome

Small headMentally retardedInternal organ abnormalities90% die before 5 months of age

Jacob’s SyndromeJacob’s Syndrome

1 in 1,800 births

47 chromosomesXYY only

#23 Trisomy Nondisjunction

Jacob’s SyndromeJacob’s Syndrome

Normal physicallyNormal mentallyIncrease in testosteroneMore aggressiveNormal lifespan

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Klinefelter SyndromeKlinefelter Syndrome

1 in 1,100 births

47 chromosomesXXY only

#23 Trisomy Nondisjunction

Klinefelter SyndromeKlinefelter Syndrome

Scarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan

Triple X SyndromeTriple X Syndrome

1 in 2,500 births

47 chromosomesXXX only

#23 TrisomyNondisjunction

Triple X SyndromeTriple X Syndrome

Normally physically

Normal mentallyFertile

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There are traits that are controlled by There are traits that are controlled by one gene with 2 alleles. Often, one is one gene with 2 alleles. Often, one is dominantdominant and the other is and the other is recessiverecessive

Example:Example:

widow’s peaks and dimples.widow’s peaks and dimples.

Some traits are controlled by a gene Some traits are controlled by a gene with with multiple allelesmultiple alleles – 3 or more for – 3 or more for

a single trait. a single trait.

For example: blood types and skin For example: blood types and skin color in humans.color in humans.

There are 44 chromosomes that we There are 44 chromosomes that we call call autosomal chromosomesautosomal chromosomes..

However, there are 2 chromosomes However, there are 2 chromosomes that determine our sex and we call that determine our sex and we call them them sex chromosomes. sex chromosomes.

These 46 chromosomes all carrier These 46 chromosomes all carrier genes on them that determine our genes on them that determine our traits.traits.

Out of our 23 pairs of chromosomes, Out of our 23 pairs of chromosomes, 1 pair is the sex chromosomes (X 1 pair is the sex chromosomes (X and Y).and Y).

Female = XXFemale = XX Male = XYMale = XY

QuestionQuestion: What is the : What is the probability that your parents probability that your parents will have a boy or girl?will have a boy or girl?

XY (dad) x XX (mom)XY (dad) x XX (mom)

X Y

X

X

XX XY

XX XY

Phenotype:

50% boy

50% girl

Genotype:

50% XX

50% XY

Question?Question?

If my parents have 5 boys in a row, If my parents have 5 boys in a row, what is the chance they will have a what is the chance they will have a girl the next time?girl the next time?

50%

Sex-linked gene:Sex-linked gene: Some traits are carried on the Some traits are carried on the sex sex

chromosomeschromosomes. Genes on the X or Y . Genes on the X or Y chromosomes are chromosomes are sex-linked genessex-linked genes. .

These traits are These traits are passes on from parent passes on from parent to childto child. Sex- linked genes can be . Sex- linked genes can be recessive or dominant. recessive or dominant.

MALESMALES are more likely to have a are more likely to have a sex-sex-linked traitlinked trait because they only have because they only have ONE ONE X and YX and Y. The allele is . The allele is USUALLYUSUALLY on the on the X X chromosomechromosome..

Ex. colorblindness, hemophilia, hairy ears, Ex. colorblindness, hemophilia, hairy ears, muscular dystrophymuscular dystrophy

Are you colorblind?

What numbers do you see?

CarrierCarrier – person who has one recessive – person who has one recessive allele and one dominant allele for a allele and one dominant allele for a trait or trait or heterozygousheterozygous for that trait for that trait (only women can be carriers). (only women can be carriers).

Example Example

Hemophiliac carrier XHemophiliac carrier XHHXXhh

Colorblind carrier XColorblind carrier XBBXXbb

Sex linked Punnett Squares:Sex linked Punnett Squares:Question:Question: What is the probability that a carrier female What is the probability that a carrier female

and a colorblind male will have a girl who is and a colorblind male will have a girl who is colorblind (b = colorblind, B = normal)?colorblind (b = colorblind, B = normal)?

YXb

XB

Xb

XBXb

XbXb XbY

XBY

Phenotype:

25% normal boy

25% colorblind boy

25% normal girl

25% colorblind girl

Try this one on your ownTry this one on your own

Question:Question:

What is the probability that a homozygous What is the probability that a homozygous (normal vision) female and a colorblind (normal vision) female and a colorblind male will have a girl who is colorblind (b = male will have a girl who is colorblind (b = colorblind, B = normal)? colorblind, B = normal)?

XB

XB

XBXb

XBXb XBY

XBY

Xb YPhenotype:

50% normal girls

50% normal boys

Parents: XBXB x XbY

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