Transcript Cell Division: Mitosis & Meiosis

Regulation of the Cell Cycle
Chapter 10, Section 3
(p.250-253)
External Regulators
• Growth Factors
– Molecules that bind to surface receptor proteins
• Stimulate cell division
External Regulators
• Cell-Cell Recognition
– Surface proteins in direct contact
• Inhibits cell division
Internal Regulators
• CDKs
• Cyclins
– Enzymes that
“activate” other
proteins by attaching a
phosphate group
– Always present in cell
– Proteins that bind to
CDKs
– Fluctuates throughout
cell cycle
• Concentration
• Type
Stimulate cell cycle when together!
Internal Regulators
P53 & BRCA1
• Stalls cell from progressing
to next phase
– DNA can be repaired
• If damage cannot be fixed
– Apoptosis
MAD
• Prevents cell from
progressing to anaphase
when chromosomes are not
properly attached to spindle
fibers
Inhibit cell cycle!
Cancer
• Caused by
– The body’s loss of control over the cell cycle
• Stimulation of cycle
• Cells forgetting to die
– Accumulation of cells = tumor
Characteristics of Cancer
• Hyperplasia: uncontrolled cell division
• Dedifferentiation: loss of specialized functions of normal
cells
• Invasiveness: ability to grow and spread into neighboring
tissue
• Angiogenesis: promote the formation of blood vessels for
nourishment
• Metastasis: cells can detach and travel via blood to other
areas of the body, starting new tumors