The Cell Cycle Flashcards
Roles of Cell division
Reproduction & Growth & Development
Prokaryotic cells undergo ______ ________ to divide because ________________________ and the result is _____________.
- binary fission (NOT mitosis)
- they are unicellular with a single circular chromosome (simpler than eukaryotes)
- two genetically identical daughter cells
How do eukaryotic cells divide?
Mitosis
What is the centromere?
Site of attachment of chromatids and kinetochore
Name the four distinct phases of interphase
G1 -> S-phase -> G2 -> M phases
What happens during G1
GAP 1
- normal cell activities
- the cell is preparing to divide
- one copy of genome |
What happens during S phase
SYNTHESIS PHASE
1 copy of genome -> two copies
| -> |’|
What happens during G2
GAP 2
- normal cell activities
BUT cell is now committed to eventual mitosis
What happens during M phase
Mitosis (separation of chromatids)
Name the six phases of mitosis in order
Prophase -> Prometaphase -> Metaphase -> Anaphase -> Telophase -> Cytokinesis
Main process in prophase
Chromosomal condensation
How many chromosomes and chromatids are there in prophase
2 chromosomes, 4 chromatids
When do the microtubule organizing centers replicate
S phase
What happens to the microtubule organizing centers during prophase
They migrate away from the nucleus towards periphery of cell
How do microtubules move chromosomes in mitosis
- polymerization/depolymerization
- kinesin (+) end directed motor
- dyenin (DIE = negative) end directed motor
Main process of prometaphse
Nuclear envelope breakdown (NEBD), microtubules reach for chromosomes “fishing”
Stable attachment occurs when the microtubules attach to:
1.
2.
3.
- kinetochore
- other microtubules
- membrane
What happens if the microtubules misses in prometaphase
it depolymerizes
Main process of Metaphase
Chromosomes line up at metaphase plate
How are chromosomes pushed to the middle in metaphase
Polymerization and kinesin
How are chromosomes pulled to the middle in metaphase
Depolymerization and dyenin
Main process of Anaphase
Separation of chromatids
|’| -> |’ ‘|
TWO CHROMATIDS BECOME TWO CHROMOSOMES
How are chromosomes pulled to opposite poles in anaphase
Depolymerization and dyenin
How is the cell elongated in Anaphase
Overlapping microtubules (polar MTs) “pushing elbows out”
Main process of Telophase
Nuclear envelope reformation, chromosomal decondensation
“T for tit”
Main process of Cytokinesis
Separation of cytoplasm
How is the cytoplasm split during Cytokinesis
Microfilaments form cytokinetic furrow/contractile ring, myosin “walks” along MF to constrict flow
What are the three checkpoints of the cell cycle
- Restriction point at G1/S: most important, are there signals/space/nutrients to divide? Once past restriction point, cell fated for division.
- G2/M checkpoint: is DNA rep complete?
- Metaphase/Anaphase checkpoint: are all kinetochores attached by MTs?
What is cancer
Uncontrolled cell division due to accumulation of mutations
The normal function of a tumor suppressor gene is ______________ and if a mutation interferes with this, it will lead to _________________. An example of a TSG is _____.
- prevent passage through the cell cycle (brake pedal)
- uncontrolled cell division
- BRCAI (dysfunctional copy of genes predisposes you to breast cancer)
The normal function of a proto-oncogene is to ___________ and a mutation can cause __________.
- promote the cell cycle (gas pedal)
2. the gene to ignore stop signals (uncontrolled cell divsion)
