28.02.2013 Views

The Principles of Clinical Cytogenetics - Extra Materials - Springer

The Principles of Clinical Cytogenetics - Extra Materials - Springer

The Principles of Clinical Cytogenetics - Extra Materials - Springer

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

DNA, Chromosomes, and Cell Division 15<br />

Fig. 6. Overview <strong>of</strong> protein synthesis. DNA is transcribed to mRNA, which is modified to a mature transcript<br />

and then transferred to the cytoplasm <strong>of</strong> the cell. <strong>The</strong> codons are read at the ribosomes and translated with<br />

the help <strong>of</strong> tRNA. <strong>The</strong> chain <strong>of</strong> amino acids produced during translation is joined by peptide bonds to form a<br />

protein molecule.<br />

along the DNA. <strong>The</strong> looped domains coil further to give rise to highly compacted units, the chromosomes,<br />

which are visible with the light microscope only during cell division. Chromosomes reach<br />

their greatest extent <strong>of</strong> condensation during the mitotic metaphase (see Fig. 7).<br />

CHROMOSOME STRUCTURE<br />

A chromosome consists <strong>of</strong> two sister chromatids, each <strong>of</strong> which is comprised <strong>of</strong> a contracted and<br />

compacted double helix <strong>of</strong> DNA. <strong>The</strong> centromere, telomere, and nucleolar organizing regions are<br />

functionally differentiated areas <strong>of</strong> the chromosomes (see Fig. 8).

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!