Biomedical Engineering Reference
In-Depth Information
Metaphase
chromosome
30-nm chromatin
fiber
“Beads-on-a-string” form
DNA double helix
Figure 1.3
Progressive packing and condensation in the chromosome.
a nonhistone chromosome scaffold. Another class of chromatin proteins function as
structure maintenance proteins called cohesins and condensins. These help in chro-
mosome condensation and keep the sister chromatids attached during replication.
Enzymes such as helicases and topoisomerases present in the cell are responsible for
unwinding, or relaxation, of the DNA.
The size, number, and shapes of chromosomes traced at the metaphase form its
karyotype. During the metaphase stage of cell cycle, the chromosomes are condensed
to the maximum. They can be visualized by dye staining using Giemsa dye. A newly
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