KaryotypesKaryotypes

KaryotypeKaryotype A picture of the A picture of the

chromosomes chromosomes from a human from a human cell arranged in cell arranged in pairs by sizepairs by size

First 22 pairs are First 22 pairs are called autosomescalled autosomes

Last pair are the Last pair are the sex sex chromosomeschromosomes

XX female or XY XX female or XY malemale

Karyotype ProcedureKaryotype Procedure 5 ml of blood is removed from the patient.   If a fetus is being karyotyped amniotic fluid is removed

from the amniotic sac which surrounds the fetus during development. This is done with the aid of a large syringe and ultrasound picturing. There are cells which have come off the fetus in this fluid.

The white blood cells are removed from the blood or the living cells are removed from the amniotic fluid.

These cells are then cultured in a medium in which they undergo mitosis. Mitosis is stopped at metaphase using chemicals.

The cells are then placed onto a slide and spread out. They are viewed under a microscope which is specially

adapted with a camera to take a picture of the chromosomes from one of the cells.

Once the picture is taken and enlarged the chromosomes are cut out and arranged in pairs according to size and location of the centromere.

Karyotyping Karyotyping is the process by which doctors and is the process by which doctors and geneticists take pictures of the chromosomes while the geneticists take pictures of the chromosomes while the cell are undergoing mitosis. cell are undergoing mitosis.

The picture is then enlarged. The picture is then enlarged. The picture of the chromosomes are then cut up so that The picture of the chromosomes are then cut up so that

each chromosome is removed. The chromosomes are each chromosome is removed. The chromosomes are matched up and attached to a paper according to size, matched up and attached to a paper according to size, banding patterns, & centromere position. banding patterns, & centromere position.

The chromosomes pairs are numbered from largest to The chromosomes pairs are numbered from largest to smallest. smallest.

There are 22 pairs of chromosomes that are aligned first There are 22 pairs of chromosomes that are aligned first & which match up exactly. These are called & which match up exactly. These are called autosomesautosomes & will code for human body characteristics. & will code for human body characteristics.

Then the Then the sex chromosomessex chromosomes are paired, in the female are paired, in the female (XX) the chromosomes match and in the male (XY) the (XX) the chromosomes match and in the male (XY) the chromosomes do not match. chromosomes do not match.

Boy or Girl?Boy or Girl?

Y - Y - ChromosomeChromosome

X - X - ChromosomeChromosome

The Y Chromosome The Y Chromosome DecidesDecides

Normal MaleNormal Male Normal Normal FemaleFemale

MutationsMutations

MutationsMutations

Changes in the genetic codeChanges in the genetic code Failure of DNA repairFailure of DNA repair During fertilization these During fertilization these

cause birth defects (genetic cause birth defects (genetic disorders) that candisorders) that can’’t be curedt be cured

During mitosis these cause During mitosis these cause cancercancer

Types of MutationsTypes of Mutations

Mutations

Point Mutations- single nitrogen base

Chromosomal

Point MutationsPoint Mutations

Insertions, Insertions, deletions, or deletions, or changes of a single changes of a single base base

This causes frame This causes frame shifting in the shifting in the reading of the reading of the genetic codegenetic code

The coThe coww jumped over jumped over the moon.the moon.

With a deletion of the With a deletion of the ““ww ”” now becomes now becomes

The coj umpedo The coj umpedo vert hem oon.vert hem oon.

Point MutationsPoint MutationsChanging a baseChanging a base

original:original:

AUG CAUG CAAU GGCU GGC

changed:changed:

AUG CAUG CCCU GGCU GGC

Deleting or Inserting a Deleting or Inserting a basebase

original:original:

AUG CAUG CAAU GGCU GGC

changed:changed:

AUG CAUG CUUG GCG GC

The codons have shifted!The codons have shifted!

Disorders caused by a point Disorders caused by a point mutationmutation

Fragile X SyndromeFragile X Syndrome

The most common The most common mental retardation mental retardation disease besides disease besides Down SyndromeDown Syndrome

HuntingtonHuntington’’s Diseases Disease

A disease that A disease that shows symptoms shows symptoms late in life that is late in life that is highly heritablehighly heritable

Degenerative Degenerative nerve diseasenerve disease

Eventual deathEventual death

Chromosomal MutationsChromosomal Mutations

Can cause death of the zygote / fetusCan cause death of the zygote / fetus Can cause sterilityCan cause sterility Most cause distinct abnormalities – Most cause distinct abnormalities –

many are very severe many are very severe Affect physical & mental healthAffect physical & mental health

Chromosomal mutationsChromosomal mutations

1.1. DuplicationsDuplications

2.2. TranslocationsTranslocations

3.3. DeletionsDeletions

4.4. InversionsInversions

5.5. Changes in the numbers of Changes in the numbers of chromosomeschromosomes

DuplicationsDuplications

Involves a Involves a chromosome that chromosome that has a piece has a piece repeatedrepeated

Causes extra Causes extra length (info) in the length (info) in the strand.strand.

TranslocationTranslocation

Transferring a Transferring a piece of one piece of one chromosome to chromosome to another another chromosomechromosome

DeletionsDeletions Omitting or losing Omitting or losing

a piece of a a piece of a chromosomechromosome

Prader – willi syndrome

InversionInversion

Attaching a piece Attaching a piece of a chromosome of a chromosome backwardbackward

Changes in chromosome Changes in chromosome numbernumber

Having more than two copies of each Having more than two copies of each chromosomechromosome

Leads to conditions of polyploidyLeads to conditions of polyploidy Can have from 3N to 5N of a Can have from 3N to 5N of a

chromosome including the sex chromosome including the sex chromosomeschromosomes

TrisomyTrisomy

Having 3 copies of Having 3 copies of the chromosome the chromosome instead of the pair instead of the pair (3N)(3N)

Examples:Examples:

1. Down1. Down’’s s Syndrome – Syndrome – trisomy 21trisomy 21

2. Klinefelter2. Klinefelter’’s - XXYs - XXY

EdwardEdward’’s Syndromes Syndrome

MonosomyMonosomy

Having 1 copy of Having 1 copy of the chromosome the chromosome instead of the pairinstead of the pair

Example:Example:

1. Turner 1. Turner SyndromeSyndrome

PolysomyPolysomy

Having more than Having more than 3 copies of a 3 copies of a chromosome.chromosome.

Example:Example:not assigned a not assigned a name but normally name but normally found only in sex found only in sex chromosomes chromosomes XXXXYXXXXYXYYYYXYYYY

MutagensMutagens

Chemicals or agents that cause copying Chemicals or agents that cause copying errors during cell divisionerrors during cell division

1.1. Exposure to radiationExposure to radiation

2.2. Chemicals used in warChemicals used in war

3.3. Chemicals in food preservativesChemicals in food preservatives

4.4. VirusesViruses

MutagensMutagens Exposure to radiation can cause a Exposure to radiation can cause a

multitude of chromosomal mutationsmultitude of chromosomal mutations

Human Genetic DisordersHuman Genetic Disorders1.1. TurnerTurner’’s Syndromes Syndrome2.2. KlinefelterKlinefelter’’s Syndromes Syndrome3.3. MicrocephalyMicrocephaly4.4. MarfanMarfan’’s Syndromes Syndrome5.5. Prader-Willi SyndromePrader-Willi Syndrome6.6. EdwardEdward’’s Syndromes Syndrome7.7. Epidermolysis BullosaEpidermolysis Bullosa8.8. Congenital Generalized Congenital Generalized

HypertrichosisHypertrichosis9.9. Cri du ChatCri du Chat10.10. AchondroplasiaAchondroplasia11.11. GaucherGaucher’’s Diseases Disease12.12. Duchenne Muscular Duchenne Muscular

DystrophyDystrophy13.13. Fragile X SyndromeFragile X Syndrome14.14. NeurofibromatosisNeurofibromatosis15.15. HuntingtonHuntington’’ss

16.16. Xeroderma PigmentosumXeroderma Pigmentosum17.17. Phenylketonuria (PKU)Phenylketonuria (PKU)18.18. AlbinismAlbinism19.19. Tay-SachsTay-Sachs20.20. Sickle Cell AnemiaSickle Cell Anemia21.21. ProgeriaProgeria22.22. Cystic FibrosisCystic Fibrosis23.23. Cleft PalateCleft Palate24.24. PolydactylyPolydactyly25.25. ColorblindnessColorblindness26.26. HemophiliaHemophilia27.27. IchthyosisIchthyosis28.28. Spina BifidaSpina Bifida29.29. JacobJacob’’s Syndromes Syndrome30.30. AmyloidosisAmyloidosis31.31. DownDown’’s Syndromes Syndrome32.32. GastroschisisGastroschisis

AlbinismAlbinism

Phenylketonuria Testing & diagnosed child

Cleft Palate Achondroplasia

DwarfismDwarfism

Bone elongation inBone elongation in

dwarfs.dwarfs. Very painful procedureVery painful procedure

Excess or deficits can result in Excess or deficits can result in obvious skeletal obvious skeletal malproportions.malproportions.

Twelve-year-old boy with pituitaryTwelve-year-old boy with pituitarygigantism measuring 6'5" with his mother.gigantism measuring 6'5" with his mother.Not the coarse facial features andNot the coarse facial features andprominent jaw.prominent jaw.

Picture 1. Gigantism and Picture 1. Gigantism and acromegaly. The author with acromegaly. The author with a statue of Robert Wadlow, a statue of Robert Wadlow, the "Alton Giant," who was the "Alton Giant," who was the tallest person ever the tallest person ever recorded. He measured 8 recorded. He measured 8 feet 11 inches at the time of feet 11 inches at the time of his death. his death.

Progeria

Sickle cell

Microcephaly

CGH Duchenne Muscular Dystrophy

Polydactyly

Epidermolysis Bullosa

Prader Willi SyndromePrader Willi Syndrome

““The Cry of the CatThe Cry of the Cat””