BME 80H Lecture Notes - Lecture 8: Down Syndrome, Chromosomal Rearrangement, Science News
4 Jun 2018
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Lecture #8- Cytogenetics, Chromosomal Aberrations and Human Disease
(chapter 7 p. 152/150; chapter 6 all)
Part I: Cytogenetics: the study of chromosomes and their behavior in a cell.
I. Examining human chromosomes
A. Chromosomes have distinctive banding patterns when treated with
dyes (figures 6.4, 6.8)
Main dye = Giemsa
Produces G-banded chromosomes
B. Nomenclature of Chromosomes and their parts
Classifications (figures 6.2/6.3, 6.5, http://www.biologia.uniba.it/
rmc/2-YAC-BAC/BAC-Chromosome/ideograms/10.html):
Whole Chromosome: centromere location,
chromosome size and banding pattern.
Metacentric- Chromatid in the middle, perfect X.
p=q
Submetacentric- Chromatid is a little higher than
middle, more like a cross- p<q
Acrocentric- Majority of chromosome is beneath
the chromatid- p<<<<q
Chromosome Arms: Separated by the centromere
p (short) and q (long)
Chromosome Regions: numbered starting at the
centromere
find more resources at oneclass.com
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Chromosome Bands: within each region. Numbered
in the direction away from the centromere. (note error
in book figure 6.5)
find more resources at oneclass.com
find more resources at oneclass.com
C. Analyzing karyotypes
1. Visible chromosomal aberrations:
translocation (t)- material from one chromosome is
transferred to another, non-homologous
chromosome.
duplication (dup)- segment of a chromosome is
duplicated.
deletion (del)- segment of a chromosome is deleted.
Nomenclature of Chromosomal aberrations (Table 6.2)
Total # Chromosomes, aberration type, Chromosome #
involved
2. Chromosome Painting (figure 6.9)
Uses fluorescent probes that bind to specific chromosomes, giving them distinct
colors
Used for Karyotype = spectral karyotype
Genomic Instability = associated with cancer
II. Diagnosis of chromosomal abnormalities
A. Adults: make a Karyotype using cells from one of the following sources
(figures 6.6, 6.7):
White blood cells (leukocytes)
Skin cells (fibroblasts)
Biopsied Tissue (tumor cells)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture #8- cytogenetics, chromosomal aberrations and human disease (chapter 7 p. 152/150; chapter 6 all) Part i: cytogenetics: the study of chromosomes and their behavior in a cell: examining human chromosomes, chromosomes have distinctive banding patterns when treated with dyes ( gures 6. 4, 6. 8) Produces g-banded chromosomes: nomenclature of chromosomes and their parts. Whole chromosome: centromere location, chromosome size and banding pattern. Metacentric- chromatid in the middle, perfect x. p=q. Submetacentric- chromatid is a little higher than middle, more like a cross- p
