Do you know what an amniocentesis is?

Karyotype An orderly display of magnified images of the individual’s chromosomes Shows the chromosomes as they appear in metaphase.

What is a Normal Karyotype? We are supposed to have 46 total chromosomes in each cell (22 pairs of autosomes = 44, + 2 sex chromosomes).

Amniocentesis Take fluid from amniotic fluid around the baby Amniocentesis Blood draw Chorion sac draw

Amniocentesis Video yOXt0https:// yOXt0

Preparing a Karyotype 1. Use blood cells.

Essay: Preparing a Karyotype 2. Burst RBC (red blood cells-have no nucleus) in hypotonic solution. Release WBC (white blood cells).

Essay: Preparing a Karyotype 3.Use a centrifuge to separate the white blood cells from the rest of the blood fluid centrifuge

Preparing a Karyotype 4. Add chemical (colchicine) to stop the chromatids in metaphase (stops spindle fibers from forming) making a karyotype video

Preparing a Karyotype (cont) 5. Drop on a slide.

Preparing a Karyotype (cont) 5. Take a picture 6.Sort by size and shape from largest to smallest

Types of Karyotypes Fluorescent to detect a marker showing certain defect karyotype procedure videokaryotype procedure video 4:29

Karyotype An arrangement of chromosome pairs according to size and shape

KARYOTYPE : Human Chromosomes

Human male karyotyp e, written as 46 XY

Human female karyotype, written as 46 XX

Types of Karyotypes Ideogram: bands locate sites on chromosome

Normal Karyotype WHY? Is it a Male or a female?

Down Syndrome Karyotype Trisomy 21 Due to nondisjunction (chrom did not separate evenly)

KARYOTYPE: How it is useful In order to study differences in size, shape, and chromosome number (too few or too many) Determines the sex of the child Usually done for humans when a known chromosomal disorder runs in family –(i.e. Down Syndrome) Can be done for any organism Genetic differences between species over time

Chromosomes p Centromere q Chromosome 5

Centromere Dark (G) bands Short arm p (petit) Long arm q Light bands Telomere Chromosomes as seen at metaphase during cell division

A pair of homologous chromosomes (number 1) as seen at metaphase Locus (position of a gene or DNA marker) Allele (alternative form of a gene/marker)

Total Genes On Chromosome: genes in region marked red, 20 are shown FZD2 AKAP10 ITGB4 KRTHA8 WD1 SOST MPP3 MLLT6 STAT3 BRCA1breast cancer 1, early onset GFAP NRXN4 NSF NGFR CACNB1 HOXB9 HTLVR ABCA5 CDC6 ITGB3 Chromosome 17 source: Human Genome Project Genes are arranged in linear order on chromosomes

NONDISJUNCTION: Definition and Results Chromosomal mutations form during meiosis when homologous chromosomes fail to separate Results in abnormal number of chromosomes in gametes, which can possibly lead to a disorder in the offspring

0Meiotic%20Nondisjunction%20 Meiosis%20II.htm Watch candy video

What is wrong with this karyotype?

Down Syndrome Trisomy 21 Folds over eyes Sluggish muscles Mental Problems (IQ often below 50)- but Some much higher

Down Syndrome The most common chromosome number abnormality Small head, ears, mouth round face, short neck and arms flattened nose bridge small, irregular teeth

Down Syndrome Short Stature heart defects susceptibility to respiratory infection, leukemia, ADHD, Alzheimer’s We Are More ALike Than DifferentWe Are More ALike Than Different (2:40)

Does the mother’s age matter? As the age of the mother increases above 30, the frequency of Trisomy 21 also increases

Edward’s Syndrome – (autosome) three copies of chromosome 18 –Karyotype shows 47 chromosomes (Trisomy 18) –Results in failure of all organ systems, death after a few months

Abnormal Sex Chromosomes 47 XXY syndrome male testes small (sterile) breast enlargement feminine body contours (wider hips) 1 in 500 to 1,000 newborn males Klinefelter’s

Klinefelter’s Syndrome also XXYY, XXXY, XXXXY

TURNER SYNDROME XO (only one X) Short often web of skin between neck and shoulders sterile poor breast development

NONDISJUNCTION: Examples of Disorders Turner’s Syndrome – (sex chromosome) – only one X chromosome is inherited –Karyotype 45, X –Results in sterile female

Turner Karyotype

“Supermale” – (sex chromosome) – extra Y chromosome is inherited –Karyotype 47, XYY –Usually results in sterile, more violent, decreased intelligence, taller male

Triploid seedless watermelon Larger polyploid strawberry

What about… MUTATIONS?

Chromosomal Mutations most often brought on by problems that occur during meiosis or by mutagens (chemicals, radiation, etc.) = cancer- causing agent Often harmful

Can you find the changes?

DELETION Fragment of the chromosome is lost Could even be fatal

Duplication Fragment of one chromosome attaches to a homologous chromosome Maybe no harm.

Translocation Fragment reattaches in reverse direction (less likely to produce harm)

Translocation If all parts are transferred evenly, then no harm. If also duplication or deletion, then changes in genetic make-up.

INVERSION The chromosome breaks in two places, a piece of the chromosome is removed and the chromosome pieces remaining rejoin.

Inversions Inversions, by definition, do not involve loss or gain of chromosomal material. chromosomal mutations (Mcgraw Hill)chromosomal mutations Click mutations

INVERSION Chromosome 10 has an inversion

Staining Chromosomes yellowChromosomes from the father of a child... a portion of chromosome 11 (blue) has been transferred to chromosome 1(yellow).