The
above picture shows the human chromosomes. There are
supposed to have 23 pairs of chromosomes. However, the
person has 1 more chromosome 21 due to incomplete
separation during meiosis. He
suffers from Down's Syndrome. |
Purpose
of chromosomes. A
normal human cell contains 46 molecules of DNA. The length
of these DNA molecules add up to 2.2 meters long. When the
cells divide, the DNA must first replicate, and
divide equally between the daughter cells. But as you can
imagine, the chance of DNA strands getting entangled with
one another is very high. Thus, as the cell divides, the
entangled DNA may break and important information may be
lost.
In order to ensure equal distribution of
genetic material to daughter cells, the DNA strands are
coiled and condensed to form chromosomes. Chromosomes are
about 0.000006 meters in length and are transcriptionally
inactive. They have a packing ratio of 8000:1 and is highly
condensed. This reduce in length will make it much easier to
divide them during mitosis and meiosis.
Related Topics:
Structure
of DNA
Paternal
and Maternal Chromosomes
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