## Abstract Mouse embryonic stem cells have an unlimited lifespan in cultures if they are prevented from differentiating. After differentiating, they produce cells which divide only a limited number of times. These changes seen in cultures parallel events that occur in the developing embryo, where
Duplication of the bacterial cell and its initiation
β Scribed by S. Bleecken
- Publisher
- Elsevier Science
- Year
- 1969
- Tongue
- English
- Weight
- 1018 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0022-5193
No coin nor oath required. For personal study only.
β¦ Synopsis
The model of Cooper & Helmstetter (1968) describes the relationship between DNA replication and the division cycle of bacteria at balanced growth. In order to render this model applicable to unbalanced growth we suggest a specific mechanism initiating the DNA replication and acting as an oscillatory pacemaker for several fundamental processes within the bacterial cell. From the improved model, the quantities of cell components (genetic markers, DNA, 'nascent' replication points, number of nuclei and number of cells) as well as the lag times, after which these components respond to a shift-up, are calculated. Experimental data quoted in the literature are in good agreement with the predictions based on the model. Theoretical and experimental results indicate that Maaloe & Kjeldgaard's (1966) theorem of constant macromolecular chain growth rate does not hold for the formation of both nascent replication points and ribosomes.
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