My-toes-is (Mitosis) Flashcards
Phases of Mitosis in Order:
(Interphase) Prophase Prometaphase Metaphase Anaphase Telophase
Here DNA condenses into Chromosomes (Chromatin –> Chromsomes)
Prophase
This phase features the initiation of the mitotic spindle.
Prophase
Dismantling of the nuclear envelope & centrosomes moving to poles.
Prometaphase
Spindles attach to chromosomes & pushing battle begins!
Prometaphase
Following the ol’ pushy pushy the chromosomes line up @ the cell equator.
Metaphase
In metaphase, spindle fibers attache to the centromere @ the…
Kinetochore
What 2 conditions must be met to move into anaphase?
Chromosomes lined up @ equator
Each chromosome has 2 spindles attached
The characteristic V shape should tell you that we’re in…
Anaphase
In Anaphase, sister chromatids…
Separate!
How do sister chromatids separate?
Spindle fibers shorten, pulling chromatids apart and toward centrosome.
At the end of Anaphase we have…
Equivalent & complete set of chromosomes on each pole!
This is the opposite of prophase & prometaphase. The unpacking of apartment.
Telophase
In telophase 2 _____ ___________ reform around each set of chromosomes making 2 nuclei.
Nuclear Envelopes
What happens to chromosomes in telophase?
Disperse back to chromatin
And what of the spindle fibers?
Degenerate
Once nuclear division is complete we have one cell, 2 daughters and 2 nuclei. Thus completes _____________.
Karyokinesis
If karyokinesis completes and cytokinesis does not we are left with a cell which has:
2 Nuclei
Giant Cells! Keep growing (Slime moulds, mammalian skeletal muscle)
Animals complete cytokinesis by:
Cleavage Furrow
Cytokinesis in plants?
Cell plate - bricklayer seperating two cells
If the cell cycle control is met =
Health maintained, and keeps going in cycle
If not met= =
Uncontrolled growth, cancer, etc, stops until met
The three checkpoints of the cell cycle?
G1
M
G2
G1 Requirements?
Cell large enough?
Enough nutrients?
Growth factors present?
DNA Undamaged?
If met? If not?
Met - will pass G1 checkpoint
Not met - will stop.
When G1 isn’t met and stops it moves into:
G0. For cells that will never divide :(
A signal is produced by the…
Growth Factor
The response?
Makes protein called G1 cyclin
Cyclin does what and to whom?
CDKP AS-PP
Cyclin-dependent kinase phosphorylates
Activates S-Phase Proteins
When S-Phase proteins are activated?
DNA Replication (S Phase) Can occur
At the end of G2 (After S Phase), what is required?
Successful DNA replication
Undamaged DNA - Big errors?
Once passed G2 checkpoint enters…
M Phase - Mitosis
G2 Cyclin Protein?
Cyclin-Dependent Kinase+G2 Cyclin leads to Inactive MPF
MPF?
Maturation Promoting Factor
How does MPF Activate?
Activating Phostatase. Cuts off phosphate group & MPF Active
At the end of Metaphase?
Metaphase Checkpoint
Requirements for Metaphase checkpoint?
All chromosomes lined up with 2 spindles
If not attached to 2 spindles?
Resulting cells will have mistakes
Binary Fission =
Round the clock DNA synthesis. Never stops.
Differences between BF & Mitosis?
CO1NN
No nuclei No nuclear envelope No Organelles No Centrosomes One chromosome
How does a cell split in BF?
Cell elongates & pinches off in centre
