Chapter 7.5: The Cell Cycle and Cell Death Are Highly Regulated in Eukaryotes

Flashcards from Chapter 7.5 of Principles of Life, 3rd Edition.

Prokaryotic cell division

This is primarily triggered by the presence of favorable environmental conditions, at which DnaA protein binds DNA for replication and then forms a Z-ring

• Continues as long as sufficient nutrients are available and DNA remains undamaged until completion

Eukaryotic cell division

This is triggered only after successfully completing the cell cycle with no errors and accumulating resources

• Growth factors stagger division times according to the needs of the organism

Restriction point (R point)

The point between the G1 and S phase in a eukaryotic cell where internal signals take over to ensure cell cycle completion, after suitable conditions are signaled

• Signals within the cell diffuse to ensure correct event handling

Cyclin-dependent kinases (CDKs)

The molecular activators that phosphorylate cell cycle regulator proteins in eukaryotes

• Requires the presence of specific cyclins to expose their active sites, which are broken down at different stages of the cell cycle

Cell cycle checkpoints

Points during the cell cycle regulated by specific CDKs that require successful checks to proceed, located at:

• The G1 to S transition (no DNA damage)

• S phase (no DNA damage or incomplete replication)

• G2 phase (no DNA damage)

• Metaphase (chromosome attachment to spindles)

Necrosis

Type of cell death that occurs when a cell is damaged or starved of nutrients

• Results in bursting or materials that can inflame other tissues

Apoptosis

A genetically programmed series of events that result in cell death, triggered by:

• Damaged cell function

• Lack of purpose for the host organism

• Inability to divide further due to chromosome shortening

• Infection control

Resulting material is often broken into membranous lobes or digested for use elsewhere