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Sex-Linked Traits Sex-Linked Traits and Karyotypes and Karyotypes Pre AP Pre AP

Sex-Linked Traits and Karyotypes

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Sex-Linked Traits and Karyotypes. Pre AP. Hemophilia. Read the passage about hemophilia in dogs Answer the following questions in your Bell Ringer journal Do sex-linked disorders happen in humans only? Is it important to know if a trait is sex-linked or not? Why or why not? - PowerPoint PPT Presentation

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Page 1: Sex-Linked Traits and Karyotypes

Sex-Linked Traits and Sex-Linked Traits and KaryotypesKaryotypes

Pre APPre AP

Page 2: Sex-Linked Traits and Karyotypes

HemophiliaHemophilia

Read the passage about hemophilia in Read the passage about hemophilia in dogsdogs

Answer the following questions in your Answer the following questions in your Bell Ringer journalBell Ringer journal– Do sex-linked disorders happen in humans Do sex-linked disorders happen in humans

only?only?– Is it important to know if a trait is sex-linked Is it important to know if a trait is sex-linked

or not? Why or why not?or not? Why or why not?– Does it surprise you to find that there are Does it surprise you to find that there are

similar genetic disorders in dogs as humans? similar genetic disorders in dogs as humans? Explain.Explain.

Page 3: Sex-Linked Traits and Karyotypes

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.

Page 4: Sex-Linked Traits and Karyotypes

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.

Page 5: Sex-Linked Traits and Karyotypes

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.

Page 6: Sex-Linked Traits and Karyotypes

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

Page 7: Sex-Linked Traits and Karyotypes

Each egg produced by an ovary contains Each egg produced by an ovary contains one X chromosomeone X chromosome

Each sperm produced by a testicle Each sperm produced by a testicle contains either one X chromosome OR contains either one X chromosome OR one Y chromosomeone Y chromosome

The X chromosome is larger than the Y The X chromosome is larger than the Y chromosome and holds more geneschromosome and holds more genes

Each animal has its own sex Each animal has its own sex chromosomes and sex determination chromosomes and sex determination based on those chromosomesbased on those chromosomes

Page 8: Sex-Linked Traits and Karyotypes

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

Page 9: Sex-Linked Traits and Karyotypes

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%

Page 10: Sex-Linked Traits and Karyotypes

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. .

This term is historically used to describe This term is historically used to describe traits housed on the X chromosome traits housed on the X chromosome

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.

Page 11: Sex-Linked Traits and Karyotypes

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 X and YONE X and Y. The allele is . The allele is USUALLYUSUALLY on on the the X chromosomeX chromosome..

Fathers pass on to daughters only; Fathers pass on to daughters only; mothers pass to sons and daughtersmothers pass to sons and daughters

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

Page 12: Sex-Linked Traits and Karyotypes

Are you colorblind?

What numbers do you see?

Page 13: Sex-Linked Traits and Karyotypes

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

Page 14: Sex-Linked Traits and Karyotypes

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)?

Page 15: Sex-Linked Traits and Karyotypes

XB

XB

XBXb

XBXb XBY

XBY

Xb YPhenotype:

50% normal girls

50% normal boys

Parents: XBXB x XbY

Page 16: Sex-Linked Traits and Karyotypes

X-InactivationX-Inactivation

Since females have 2 X chromosomes, Since females have 2 X chromosomes, one is inactivatedone is inactivated

During development, each cell of the During development, each cell of the embryo randomly inactivates oneembryo randomly inactivates one

Every cell may have a different X Every cell may have a different X inactivated (ex. Tortoiseshell Cat)inactivated (ex. Tortoiseshell Cat)

Barr-bodies - inactive X chromosomes Barr-bodies - inactive X chromosomes lies along the inside of the nuclear lies along the inside of the nuclear envelopeenvelope

Page 17: Sex-Linked Traits and Karyotypes

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

Page 18: Sex-Linked Traits and Karyotypes

Carriers do not show that particular Carriers do not show that particular trait phenotypically but have a chance trait phenotypically but have a chance to pass the trait on to their child.to pass the trait on to their child.

Carrier – half colored

Page 19: Sex-Linked Traits and Karyotypes

Reading a Pedigree

Task 2:

Go to the lab tables.

Each person should have one answer sheet.

Lets do the first one together.

As a group, finish analyzing the pedigrees. If you have extra time, work on conclusion questions (homework if not completed in class).

Task 1: Genotyping a pedigree chart

Page 20: Sex-Linked Traits and Karyotypes

??

Page 21: Sex-Linked Traits and Karyotypes

Ticket OutTicket Out

Obtain a paper with a problem that Obtain a paper with a problem that asks you to create your own asks you to create your own pedigree… due on your way out of pedigree… due on your way out of the classroom.the classroom.

Page 22: Sex-Linked Traits and Karyotypes

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

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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?)

Page 26: Sex-Linked Traits and Karyotypes

Genetics Disorders Genetics Disorders and Mutationsand Mutations

Page 27: Sex-Linked Traits and Karyotypes

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

Page 28: Sex-Linked Traits and Karyotypes

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.

Page 29: Sex-Linked Traits and Karyotypes

Cystic FibrosisCystic Fibrosis Recessive genetic disorder where the body produces Recessive genetic disorder where the body produces

abnormally thick mucus in the lungs and intestines making abnormally thick mucus in the lungs and intestines making respiration and digestion difficultrespiration and digestion difficult

Caused by a mutation in a gene. Body produces mucus Caused by a mutation in a gene. Body produces mucus which builds up in the breathing passages of lungs and which builds up in the breathing passages of lungs and pancreas (the organ that helps to break down and absorb pancreas (the organ that helps to break down and absorb food) food)

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

Page 30: Sex-Linked Traits and Karyotypes

Sickle Cell AnemiaSickle Cell Anemia Sickle cell is a recessive genetic disorder that Sickle cell is a recessive genetic disorder that

affects the blood’s hemoglobin. Hemoglobin is affects the blood’s hemoglobin. Hemoglobin is the protein in your blood that carries oxygen.the protein 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 causes it to form The ‘sickle shape’ of the cell causes it to form clots easily and the protein doesn’t allow the red clots easily and the protein doesn’t allow the red blood cell to carry very much oxygen.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)

Page 31: Sex-Linked Traits and Karyotypes

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 a recessive sex-linked disorder on the X This is a recessive 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.

Page 32: Sex-Linked Traits and Karyotypes

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.

Page 33: Sex-Linked Traits and Karyotypes

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

Page 34: Sex-Linked Traits and Karyotypes

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

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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

Page 36: Sex-Linked Traits and Karyotypes

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

Page 37: Sex-Linked Traits and Karyotypes

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

Page 38: Sex-Linked Traits and Karyotypes

??

Page 39: Sex-Linked Traits and Karyotypes

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

Page 40: Sex-Linked Traits and Karyotypes

Turners SyndromeTurners Syndrome

1 in 5,000 births

45 chromosomesX only #23 MonosomyNondisjunction

Page 41: Sex-Linked Traits and Karyotypes

Turners SyndromeTurners Syndrome

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

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Cri-Du-Chat Cri-Du-Chat SyndromeSyndrome

1 in 216,000 births

46 chromosomesXY or XX

#5 Deletion of lower arm

Page 43: Sex-Linked Traits and Karyotypes

Cri-Du-Chat SyndromeCri-Du-Chat Syndrome

Moon-shaped faceHeart diseaseMentally retardedMalformed larynxNormal lifespan

Page 44: Sex-Linked Traits and Karyotypes

Aniridia-Wilms Tumor Aniridia-Wilms Tumor SyndromeSyndrome

1 in 50,000,000 births

46 chromosomesXY or XX

#11 Deletion of upper arm

Page 45: Sex-Linked Traits and Karyotypes

Aniridia-Wilms Tumor SyndromeAniridia-Wilms Tumor Syndrome

Mentally retardedGrowth retardedBlindnessTumors on kidneysShort lifespan

Page 46: Sex-Linked Traits and Karyotypes

Thirteen Q Deletion Thirteen Q Deletion SyndromeSyndrome

1 in 500,000 births

46 chromosomesXY or XX

#13 Deletion of lower arm

Page 47: Sex-Linked Traits and Karyotypes

Thirteen Q Deletion SyndromeThirteen Q Deletion Syndrome

Mentally retardedDeformed faceNo thumbsHeart diseaseShort lifespan

Page 48: Sex-Linked Traits and Karyotypes

Prader-Willi Prader-Willi SyndromeSyndrome

1 in 5,000,000 births

46 chromosomesXY=97% XX=3%

#15 Deletion of lower arm

Page 49: Sex-Linked Traits and Karyotypes

Prader-Willi SyndromePrader-Willi Syndrome

Small bird-like headMentally retardedRespiratory problemsObesityShort lifespan

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Eighteen Q Deletion Eighteen Q Deletion SyndromeSyndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#18 Deletion of lower arm

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Eighteen Q Deletion SyndromeEighteen Q Deletion Syndrome

Mentally retardedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan

Page 52: Sex-Linked Traits and Karyotypes

Cat-Eye SyndromeCat-Eye Syndrome

1 in 1,000,000 births

46 chromosomesXY or XX

#22 Deletion of bottom arm

Page 53: Sex-Linked Traits and Karyotypes

Cat-Eye SyndromeCat-Eye Syndrome

Fused fingers and toesMentally retardedSmall jawHeart problemsNormal lifespan

Page 54: Sex-Linked Traits and Karyotypes

Four-Ring SyndromeFour-Ring Syndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#4 Inversion

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Four-Ring SyndromeFour-Ring Syndrome

Cleft palateClub feetTestes don’t descendShort lifespan

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1 in 1,250 births

47 chromosomesXY or XX

#21 Trisomy Nondisjunction

Down Syndrome Trisomy

Page 57: Sex-Linked Traits and Karyotypes

Down SyndromeDown Syndrome

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

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Patau’s Trisomy Patau’s Trisomy SyndromeSyndrome

1 in 14,000 births

47 chromosomesXY or XX

#13 Trisomy Nondisjunction

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Patau’s Trisomy SyndromePatau’s Trisomy Syndrome

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

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Edward’s Trisomy Edward’s Trisomy SyndromeSyndrome

1 in 4,400 births

47 chromosomesXX=80%

XY=20%

#18 Trisomy Nondisjunction

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Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome

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

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Jacob’s SyndromeJacob’s Syndrome

1 in 1,800 births

47 chromosomesXYY only

#23 Trisomy Nondisjunction

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Jacob’s SyndromeJacob’s Syndrome

Normal physicallyNormal mentallyIncrease in testosteroneMore aggressiveNormal lifespan

?

Page 64: Sex-Linked Traits and Karyotypes

Klinefelter SyndromeKlinefelter Syndrome

1 in 1,100 births

47 chromosomesXXY only

#23 Trisomy Nondisjunction

Page 65: Sex-Linked Traits and Karyotypes

Klinefelter SyndromeKlinefelter Syndrome

Scarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan

Page 66: Sex-Linked Traits and Karyotypes

Triple X SyndromeTriple X Syndrome

1 in 2,500 births

47 chromosomesXXX only

#23 TrisomyNondisjunction

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Triple X SyndromeTriple X Syndrome

Normally physically

Normal mentallyFertile

Page 68: Sex-Linked Traits and Karyotypes

Huntington’s DiseaseHuntington’s Disease Caused by a lethal dominant gene in Caused by a lethal dominant gene in

which a section of DNA on chromosome which a section of DNA on chromosome #4 is repeated more than usual#4 is repeated more than usual

Nerve cells in the brain waste away, or Nerve cells in the brain waste away, or degeneratedegenerate

Two forms – most common is adult onset Two forms – most common is adult onset in which those affected show no signs in which those affected show no signs until 35 or 40; other is early onsetuntil 35 or 40; other is early onset

Page 69: Sex-Linked Traits and Karyotypes

Huntington’s DiseaseHuntington’s Disease Abnormal and unusual movements Abnormal and unusual movements Behavior changes Behavior changes Dementia that slowly gets worse, including Dementia that slowly gets worse, including Additional symptoms that may be associated Additional symptoms that may be associated

with this disease:with this disease:– Anxiety, stress, and tension Anxiety, stress, and tension – Difficulty swallowing Difficulty swallowing – Speech impairmentSpeech impairment

In children:In children:– Rigidity Rigidity – Slow movements Slow movements – TremorTremor

Page 70: Sex-Linked Traits and Karyotypes

Color-BlindnessColor-Blindness Have trouble seeing red, green, or blue or Have trouble seeing red, green, or blue or

a mix of these colors a mix of these colors Caused by a recessive sex-linked alleleCaused by a recessive sex-linked allele The cone cells in your eyes do not The cone cells in your eyes do not

function properly or are absentfunction properly or are absent You may not see red, blue, or green, or You may not see red, blue, or green, or

you may see a different shade of that you may see a different shade of that color or a different colorcolor or a different color

Doesn't change over time. Doesn't change over time.

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Color-BlindnessColor-Blindness

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Tay-sachsTay-sachs

Autosomal recessive disorder because of Autosomal recessive disorder because of mutation on chromosome 15mutation on chromosome 15

Infants typically appear normal until 3 to Infants typically appear normal until 3 to 6 months:6 months:

Other forms of Tay-Sachs disease are Other forms of Tay-Sachs disease are very rare.very rare.

Page 73: Sex-Linked Traits and Karyotypes

Tay-sachs DiseaseTay-sachs Disease– development slows and muscles used for movement development slows and muscles used for movement

weakenweaken– lose motor skills such as turning over, sitting, and crawlinglose motor skills such as turning over, sitting, and crawling– develop an exaggerated startle reaction to loud noisesdevelop an exaggerated startle reaction to loud noises– Eventually experience seizures, vision and hearing loss, Eventually experience seizures, vision and hearing loss,

intellectual disability, and paralysisintellectual disability, and paralysis– eye abnormality called a cherry-red spot, which can be eye abnormality called a cherry-red spot, which can be

identified with an eye examination, is characteristic of this identified with an eye examination, is characteristic of this disorder. disorder.

– Children with this severe infantile form of Tay-Sachs Children with this severe infantile form of Tay-Sachs disease usually live only into early childhood.disease usually live only into early childhood.

Page 74: Sex-Linked Traits and Karyotypes

??

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Diagnose the karyotypes cont. You have already described what is abnormal (if applicable) about the karyotypes, now you must identify what genetic disorder (if any) is portrayed using the knowledge you just received.