Keyword Hot Links for chapter 7

Most bacterial cells must compact their DNA into small volume because the cells are extremely small, yet the DNA must also be available for transcription. For example, the size of an E. coli cell is about 1 ¥ 2 micrometers, yet it contains a circular DNA molecule of 4.6 million base pairs, which if opened and stretched to its full length would be about 70 times longer than the cell itself. The keyword bacterial chromatin will connect you to a site that focus on the analysis of complete bacterial genome sequences with regard to the motifs involved in compaction of the DNA.

The centromere sequences of the chromosomes of yeast Saccharomyces cerevisiae include three conserved sequence elements that are sufficient for mitotic and meiotic segregation. The first is only 8 bp and is required for mitotic segregation, the second is a 78–86 bp A–T-rich region required for chromosome disjunction in meiosis I, and the third is a 25 bp region essential for both mitotic and meiotic segregation. The sequences of all the yeast centromeres can be retrieved and compared using the search engine at this keyword site by entering the item name cen*.

The telomeres of chromosomes are of great interest not only because they are specialized DNA-protein complexes that stabilize the ends of chromosomes but also because abnormal telomere maintenance is implicated in the progression of cancer cells (Chapter 15). In most organisms the telomeres consist of short repeating sequences that are synthesized by a telomerase enzyme containing an RNA template for the telomere repeat. You can learn more about telomere sequences and telomerases at this keyword site devoted to the structures.

Back to Keyword Hot Links for all chapters

Back to eLearning for all chapters