Unit 1- Microtubules and Motors Flashcards
Microtubule Functions
Support cell shape, intracellular transport, cell division, and cilia/flagella movement.
Microtubule Growth
Built from tubulin dimers (alpha and beta). GTP-bound tubulin favors assembly, while GDP-bound tubulin favors disassembly.
Microtubule Polarity
Has a plus end (fast-growing) and a minus end (slow-growing). The plus end often extends outward toward the cell periphery.
Dynamic Instability
Microtubules alternate between phases of growth (polymerization) and shrinkage (depolymerization)
Shrinking: Catastrophe
Growing: Rescue.
Centrosome Influence
Organizes microtubules and anchors the minus end, ensuring stability and correct direction of growth.
Pericentriolar Protein:
Gamma-tubulin helps nucleate microtubules from the centrosome
Microtubule Motor Proteins:
Kinesin: Moves cargo toward the plus end.
Dynein: Moves cargo toward the minus end.
Cilia Structure:
Motile cilia: 9+2 arrangement, involved in movement.
Primary sensory cilia: 9+0 arrangement, involved in signaling.
Cilia Movement:
Powered by dynein motors that cause microtubule doublets to slide against each other, resulting in bending.
Microtubule-targeting Drugs in Chemotherapy:
Disrupt microtubule dynamics, preventing cell division and thus targeting rapidly dividing cancer cells.
Microtubule Types in Mitosis:
Astral: Anchor the centrosome to the cell membrane.
Kinetochore: Attach to chromosomes and pull them apart.
Interpolar: Stabilize the mitotic spindle.
Astral Microtubules in Mitosis:
Help orient the spindle poles, ensuring correct chromosome segregation.
Interpolar Microtubules in Mitosis
Push the spindle poles apart to facilitate cell division.
Kinetochore Microtubules in Mitosis:
Attach to chromosome centromeres and move chromosomes to opposite poles during anaphase.
