Presentation on theme: "Karyotypes and Mutations. Karyotype An orderly display of magnified images of the individuals chromosomes Shows the chromosomes as they appear in metaphase."— Presentation transcript:
Karyotypes and Mutations
Karyotype An orderly display of magnified images of the individuals 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).
One source: Amniocentesis Take fluid from amniotic fluid around the baby Can make a karyotype to see if there is a genetic disorder
Preparing a Karyotype 1. Use blood cells.
Essay: Preparing a Karyotype 2. Burst RBC (red blood cells) 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
Preparing a Karyotype 4. Add chemical (colchicine) to stop the chromatids in metaphase (stops spindle fibers from forming)
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
Other types of Karyotypes
Types of Karyotypes Fluorescent to detect a marker showing certain defect
Types of Karyotypes Colored dyes for certain chromosomes
Types of Karyotypes Ideogram: bands locate sites on chromosome
Normal Karyotype WHY? Is it a Male or a female?
Down Syndrome Karyotype Trisomy 21
Down Syndrome Trisomy 21 Folds over eyes Sluggish muscles Mental Problems
Down Syndrome The most common chromosome number abnormality Round face flattened nose bridge small, irregular teeth
Down Syndrome Short Stature heart defects susceptibility to respiratory infection, leukemia and Alzheimers
Does the mothers age matter? As the age of the mother increases above 30, the frequency of Trisomy 21 also increases
Nondisjunction Uneven distribution of chromosomes in cell division
Abnormal Sex Chromosomes 47 XXY syndrome male testes small (sterile) breast enlargement feminine body contours Klinefelters
Klinefelters Syndrome also XXYY, XXXY, XXXXY
TURNER SYNDROME XO (only one X) short often web of skin between neck and shoulders sterile poor breast development
What about… MUTATIONS?
DELETION Fragment of the chromosome is lost
Duplication Fragment of one chromosome attaches to a homologous chromosome
Translocation Fragment reattaches in reverse direction (less likely to produce harm)
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.
INVERSION 46,XY,inv(16) The left one is normal and the right one is inverted near the centromere.
45,XX,rob(13,14) A Robertsonian translocation (an end to end fusion of #13 and #14) There is no net gain or loss of genetic material in this person so they would have a normal phenotype.
Applications Chromosomes from the father of a retarded child... a portion of chromosome 11 (blue) has been yellow transfered to chromosome 1(yellow).