BI108 Chapter 11 Notes: The Cell Cycle and Cell Division
11.1: Prokaryotic and Eukaryotic Cell Division
Division is the basis for: reproduction, growth, and repair/regeneration of tissues
In order for a cell to divide four events must occur:
1. Reproductive Signal—initiates cell division; may originate inside or outside the cell
2. Replication of DNA—so that each new cell will have identical set of genes
3. Segregation—distributing DNAto each of two new cells
4. Cytokinesis—enzymes/organelles synthesized, added to plasma membrane, and contents
*chromosome: long, thin, DNA molecule with proteins attached to it
Prokaryotes divide by binary fission
For prokaryotes, cell division results in the reproduction of the entire single-celled organism.
Binary Fission: Cell grows in size, replicates DNA, and then separates the cytoplasm/DNA into
two new cells
1) Reproductive Signals: external factors are common signals. This includes environmental
conditions and nutrient concentrations.
Ex: E. coli, the “cell division machine” if abundance of
carbohydrates are present, it can divide every 20 mins. Some stop division if
nutrient levels are low.
2) Replication of DNA: chromosomes must be replicated so that each copy can find its way
to each cell. Most prokaryotes have just one chromosome.
• To fit the cell, DNA must be compacted. The DNA folds in on itself, positive
charged (basic) proteins bind to negatively charged (acidic) proteins.
Two regions of chromosome: