Chromosomal Alterations: When Meiosis Goes Wrong Flashcards
What is a karyotype?
Representation of the chromosomes from cells of any animal (picture of chromosomes).
What happens to a cow’s chromosome structure if they have “Robertsonian Translocation?”
A fusion between 2 chromosomes at the centromere.
Explain what happens during a gene deletion or duplication.
Deletion- section of a chromosome is deleted
Duplication- section of a chromosome is repeated over and over
What is trisomy and monosomy? Which is more lethal?
Trisomy- extra chromosome
Monosomy- missing a chromosome (more lethal)
How often does Down Syndrome occur?
1/800 live births
Describe the characteristics of a Down’s individual?
Slanting eyes, single crease on palm of hands, flat nose, respiratory problems.
What do genetic councillors do for their clients?
They are able to help their clients analyze the possibility of certain traits. Helping families gain an understanding of family’s genetics and options available to them. Go over a family’s pedigree. Go over risks of genetic diseases.
What diseases do people get genetic testing for?
Duchennes, Muscular Dystrophy, Spina Bifida, Cystic Fibrosis.
What are some of the risks of amniocentesis?
Miscarriage, leak of amniotic fluid.
What shapes are used in a pedigree? What do they stand for?
Circle- female
Square- males
Triangle- unknown
What is a karyotype?
The number and visual appearance (size and banding pattern) of the chromosomes in the cell nuclei of an organism.
Where is keryotyping performed and what does it produce?
In a laboratory and produces an image of an individual’s chromosomes.
What is a karyotype used to look for?
Abnormalities in the number or structure of chromosomes
How are karyotype notions wrote?
Number of chromosomes, the specific sex chromosomes, and where possible, the specific extra autosomal chromosome
Karyotype notation: Triple X Syndrome
Reason for abnormality:
2-3 symptoms:
47, xxx
Nondisjunction (extra X chromosome)
Learning disabilities, weak muscle tone, abnormally curved pinky fingers
Karyotype notation: Klienfelters Syndrome
Reason for abnormality:
2-3 symptoms:
47, xxy
Nondisjunction (extra X chromosome)
Incomplete puberty, weak bones, low energy levels
Karyotype notation: Cri du Chat
Reason for abnormality:
2-3 symptoms:
46, xy
Part of chromosome 5 is missing (deletion of genes on chromosome)
Widely spaced eyes, weak muscle tones, low birth weight, mental retardation
Karyotype notation: Down Syndrome
Reason for abnormality:
2-3 symptoms:
47, xy + 21
Result of an extra copy of chromosome 21
Respiratory disease, short stature, prone to developing Alzheimer’s
Karyotype notation: Williams Syndrome
Reason for abnormality:
2-3 symptoms:
46, xy
The deletion of chromosome 7
Low birth rate, heart defects, low muscle tone
Karyotype notation: Turners Syndrome
Reason for abnormality:
2-3 symptoms:
45, X0
Nondisjunction (girls are missing one or part of one of their two X chromosomes)
Failure to grow at expected rate, infertility, chronic ear infections.
Karyotype notation: Fragile X
Reason for abnormality:
2-3 symptoms:
46, xy
Duplication of genes on X chromosome
Stuttering, anxiety, attention problems
How often are karyotype analysis performed per year in the US?
Over 400 000
During mitosis, what happens to the 23 pairs of human chromosomes?
They condense and are visible with a light microscope.
What does a karyotype analysis usually involve?
Blocking cells in mitosis and staining the condensed chromosomes with Giemsa dye.
What does Giemsa dye do?
Stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T), producing a dark band.
