Exam 2: Chp 17 Flashcards
Cell Cycle (42 cards)
3 major transition points of cell cycle?
1) start in G1
2) G2-to-M
3) Metaphase to anaphase
What does the G2-to-M transition check for?
If DNA has been correctly replicated and if condition conditions are favorable
What does the metaphase-to-anaphase transition check for?
if chromosomes are attached to the correct spindle poles
Prophase
chromosomes condense and miotic spindle assembles
What are the three types of microtubules of the miotic spindle?
1) kinetochore
2) non-kinetochore
3) astral
When do centrioles seperate?
G1
When do centrioles replicate?
S-phase
Kinesin-5
two motor domains that walk towards the plus end of microtubules to orient them relative to one another
cytoplasmic dynein
attach to plasma membrane and move towards minus end of microtubule to position the miotic spindle
Kinesin 14
has stationary domain bound to microtubule and motor domain at other walks to minus end
Kinesin 4/10
carry chromosomes to the plus end of the microtubule
Prometaphase
nuclear envelope breakdown, chromosomes attach to spindle microtubules
Ndc80
attaches microtubule to kinetochore
What mediates attachment of chromosomes to correct spindle poles?
tension on between the spindle poles
Metaphase
chromosomes align at the equator
What mediates alignment of chromosomes at the equator?
partially motor proteins like kinesin and dynein
Anaphase
chromosomes separate
Telophase
daughter chromosomes arrive at poles and a new nuclear envelope develops
Cytokinesis
physical separation of cell into 2 daughter cells mediated by the contractile ring
Contractile ring
actin and myosin ring and cleaves cell into 2
Cleavage furrow
first visible sign of cytokinesis
Midbody
actin/myosin rich segment left right before cells are fully separated
What mediates assembly of the contractile ring?
RhoA -> formin / Rho associated kinases -> actin filament formation / myosin phosphatase inactivation, myosin 2 activation (light phosphorylation) -> movement and assembly
Mitogens
stimulate cell division
