Lecture 8 Flashcards
What are 2 types of reproduction by dividing into two?
- Binary fission
- Mitosis
Which type of reproduction do unicellular organisms (such as prokaryotes) use?
Binary fission.
Which type of reproduction do multicellular organisms (such as eukaryotes) use?
Mitosis.
How does binary fission work?
The circular bacterial chromosome is replicated and the cell begins to separate, forming a septum in between the two cells, before completely pinching off.
What are the 2 main phases of the eukaryotic cell cycle?
- Interphase - the time in between cell division
- M phase - when the cells divide
What are the 3 phases within interphase?
- G1
- S
- G2
What are the 2 phases within M phase?
- Mitosis - when the DNA is divided
- Cytokinesis - when the cells divide
What happens during G1 phase or gap phase 1?
It is the primary growth phase and the longest phase.
What happens during S phase or Synthesis phase?
Replication of the DNA.
What happens during the G2 phase or gap 2 phase?
Organelles are replicated and the microtubules are organized.
What happens during the C phase or cytokinesis phase?
The 2 new cells separate.
What types of cells take longer to complete the cell cycle?
Mature cells.
How long do typical mammalian cells take to complete the cell cycle?
24 hours.
What are 4 phases of mitosis?
- Prophase
- Prometaphase
- Anaphase
- Telophase
What is a centromere?
A point of constriction.
What is the kinetochore?
The attachment site for microtubules.
How do chromatids stay together?
Both sister chromatid has a centromere that attach to each other.
What is the prophase?
When the chromosomes are condensed, the spindle apparatus is assembled, and the nuclear envelope breaks down.
How is the spindle apparatus formed?
Two centrioles move to opposite poles.
What is an aster?
A radial array of microtubules in animals.
Do plants have centrioles or asters?
no.
What is the prometaphase?
When the microtubules attach to the kinetochores and the chromosomes are moved to the center of the cell.
What is the metaphase?
When the chromosomes are aligned with the metaphase plate.
What is the anaphase?
When the chromatids are pulled apart to opposite poles.
What is the telophase?
When the spindle apparatus disassembles and the nuclear envelope forms around each set of sister chromatids and the chromatids relax.
After separating, what are the sister chromatids called?
Chromosomes.
What is cytokinesis?
When the cells split into equal halves.
How is cytokinesis different in plant cells and animal cells?
In animals the actin filament constricts to separate the 2 cells, but in plants the cell plate forms between the nuclei.
What are controls of the cell cycle?
The cell cycle has 2 irreversible points and can be put on hold at specific points called checkpoints.
What are the two irreversible points of the cell cycle?
- Once the chromosomes are replicated
- Once the sister chromatids are separated.
Where are the 3 checkpoints in the cell cycle?
- G1/S checkpoint
- G2/M checkpoint
- Late metaphase checkpoint
What is the G1/S checkpoint?
checkpoint where the cell decides whether or not to reproduce.
What is the G2/M checkpoint?
When the cell commits the mitosis and checks to see if the DNA was replicated properly.
What is the late metaphase checkpoint?
The cell checks to make sure the chromosomes are attached to the spindle.
What are 3 cell cycle control factors?
- MPF
2.Cyclins - cdc2
What is MPF?
Maturation-promoting factor.
What is MPF made of?
Cyclin and cdc2.
What is cdk?
Cyclin-dependent kinase or cyclin complex.
what is ckd important for?
driving the cell cycle.
What activates and inactivates the cdk?
phosphorylation.
