Karyotypes

Karyotypes

Karyotypeü ü ü ü A picture of thechromosomes from ahuman cell arrangedin pairs by sizeFirst 22 pairs arecalled autosomesLast pair are thesex chromosomesXX female or XYmale

Karyotype Proceduren n n n n n n 5 ml of blood is removed from the patient.If a fetus is being karyotyped amniotic fluid is removed fromthe amniotic sac which surrounds the fetus duringdevelopment. This is done with the aid of a large syringe andultrasound picturing. There are cells which have come off thefetus in this fluid.The white blood cells are removed from the blood or the livingcells are removed from the amniotic fluid.These cells are then cultured in a medium in which theyundergo mitosis. Mitosis is stopped at metaphase usingchemicals.The cells are then placed onto a slide and spread out.They are viewed under a microscope which is specially adaptedwith a camera to take a picture of the chromosomes from oneof the cells.Once the picture is taken and enlarged the chromosomes arecut out and arranged in pairs according to

n n n n n n Karyotyping is the process by which doctors andgeneticists take pictures of the chromosomes while thecell are undergoing mitosis.The picture is then enlarged.The picture of the chromosomes are then cut up so thateach chromosome is removed. The chromosomes arematched up and attached to a paper according to size,banding patterns, & centromere position.The chromosomes pairs are numbered from largest tosmallest.There are 22 pairs of chromosomes that are aligned first& which match up exactly. These are called autosomes& will code for human body characteristics.Then the sex chromosomes are paired, in the female(XX) the chromosomes match and in the male (XY) thechromosomes do not match.

Boy or Girl?The Y Chromosome DecidesY - ChromosomeX - Chromosome

Average MaleAverage Female

Mutations

Mutationsn Changesin the genetic coden Failure of DNA repairn During fertilization these causebirth defects (geneticdisorders) that canʼt be curedn During mitosis these causecancer

Types of MutationsMutationsGene MutationsChromosomal

Gene Mutationsn Insertions ordeletions (frameshiftmutations),orchanges of a singlebase (pointmutations)This causes codonerrors and affectsamino acid translationThe cow jumped overthe moon.With a deletion of the“w” now becomesThe coj umpedo verthem oon.

Point Mutations vs. FrameshiftChanging a baseoriginal:AUG CAU GGCchanged:AUG CCU GGCDeleting or Inserting abaseoriginal:AUG CAU GGCchanged:AUG CUG GCThe codons have shifted!

Chromosomal Mutationsn n n n Can cause death of the zygote / fetusCan cause sterilityMost cause distinct abnormalities – manyare very severeAffect physical & mental health

Types of ationsDeletionsInversionsChanges in the numbers ofchromosomes

Duplicationsn n Involves achromosome that hasa piece repeatedCauses extra length(info) in the strand.

Translocationn Transferring a pieceof one chromosometo anotherchromosome

Deletionsn Omitting or losing apiece of achromosomePrader – willisyndrome

Inversionn Attaching a piece of achromosomebackward

Changes in chromosome numbern n Having more than two copies of eachchromosomeCan have from 3N to 5N of a chromosomeincluding the sex chromosomes

TrisomyHaving 3 copies of thechromosome instead ofthe pair (3N)n Examples:1. Downʼs Syndrome –trisomy 212. Klinefelterʼs - XXYn

Edwardʼs Syndrome

MonosomyHaving 1 copy of thechromosome insteadof the pairn Example:1. Turner Syndromen

PolysomyHaving more than 3copies of achromosome.n Example:not assigned a namebut normally foundonly in sexchromosomesXXXXYXYYYYn

Disorders caused by a point mutationFragile X Syndromen The most commonmental retardationdisease besides DownSyndromeHuntingtonʼs Diseasen n n A disease that showssymptoms late in lifethat is highly heritableDegenerative nervediseaseEventual death

Mutagensn Chemicals or agents that cause copying errorsduring cell division1. Exposure to radiation2. Chemicals used in war3. Chemicals in food preservatives4. Viruses

Mutagensn Exposure to radiation can cause a multitude ofchromosomal mutations

Human Genetic rʼs SyndromeKlinefelterʼs SyndromeMicrocephalyMarfanʼs SyndromePrader-Willi SyndromeEdwardʼs SyndromeEpidermolysis BullosaCongenital GeneralizedHypertrichosisCri du ChatAchondroplasiaGaucherʼs DiseaseDuchenne MuscularDystrophyFragile X SyndromeNeurofibromatosisHuntingtonʼs31. Xeroderma Pigmentosum Phenylketonuria (PKU) Albinism Tay-Sachs Sickle Cell Anemia Progeria Cystic Fibrosis Cleft Palate Polydactyly Colorblindness Hemophilia Ichthyosis Spina Bifida Jacobʼs Syndrome Amyloidosis Downʼs Syndrome Gastroschisis

Albinism

Cleft PalatePhenylketonuria Testing & diagnosed childAchondroplasia

Dwarfism

Bone elongation indwarfs.n Very painful proceduren

n Excess or deficits can result inobvious skeletal malproportions.Twelve-year-old boy with pituitarygigantism measuring 6'5" with his mother.Not the coarse facial features andprominent jaw.n Picture 1. Gigantism andacromegaly. The author with astatue of Robert Wadlow, the"Alton Giant," who was the tallestperson ever recorded. Hemeasured 8 feet 11 inches at thetime of his death.

Sickle cellProgeriaMicrocephaly

CGHDuchenne Muscular DystrophyPolydactyly

EpidermolysisBullosa

Prader Willi Syndrome

“The Cry of the Cat”

" The picture of the chromosomes are then cut up so that each chromosome is removed. The chromosomes are matched up and attached to a paper according to size, banding patterns, & centromere position. " The chromosomes pairs are numbered from largest to smallest. " There are 22 pairs of chromosomes that are aligned first