Karyotypes and Mutations Karyotype An orderly display of

Karyotypes and Mutations

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

Preparing a Karyotype • 1. Use blood cells.

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

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 video 4: 29

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)

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 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

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

Klinefelter’s Syndrome • also XXYY, XXXXY

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

Turner Karyotype

• 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. ) = cancercausing 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) • Click mutations

• Chromosome 10 has an inversion INVERSION

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