3.2.2 - Mitosis and Cell Cycle Flashcards
What are the 4 stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase (cytokinesis)
What does the diagram show?
Anaphase
Cancer is caused by uncontrolled mitosis. How do most cancer drugs work?
- Preventing DNA replication/
- Inhibiting metaphase stage of mitosis by interfering with spindle formation.
What happens during prophase?
- DNA condenses into chromosomes (becomes visible)
- Centrioles move to opposite poles of cell and spindle fibres are released to form a spindle apparatus.
- The nucleolus and nuclear envelope break down.
What does the diagram show?
Telophase (leading to cytokinesis)
Describe the process of bacterial binary fission
- Circular DNA and plasmids replicate.
- The cell membrane begins to grow and pinches in around the two circular DNA molecules.
- A new cell wall forms between the two circular DNA molecules dividing the cell into 2 idenitcal daughter cells.
- The cells have variable numbers of plasmids.
What does the diagram show?
Metaphase
When would mitosis not result in 2 identical daughter cells?
If there was a mutation (very rare)
Gametes (eggs and sperm) are haploid cells. What is meant by this?
They contain only 1 set of unparied chromosomes.
What is mitosis important for?
- Growth
- Repair of damaged cells.
- Reproduction (single celled organisms)
Describe what happens when a virus replicates.
- Attachment to host cell using attachment proteins on their surface.
- Injection of nucleic acid into host cell.
- Nucleic acid provides instructions for host cell’s metabolic machinary to start producing new viral components e.g. enzymes and structural proteins.
- Viral components packaged into new viruses.
What happens during metaphase?
Chromosomes are positioned along equator of cell by spindle fibres.
What is the product of mitosis?
2 daughter cells that have the same number of chromosomes as the parent cell and each other.
What does the diagram show?
Prophase
The regular cycle of division separated by periods of cell growth is called…
the cell cycle
How much of a single cell cycle is spent in interphase?
approximately 90%
Bacterial cells replicate in a similar way to mitosis. What do we call their method of replication?
Binary Fission
The rate of mitosis is controlled by…
- The environment of the cell
- ‘Growth factors’.
- Two genes.
What happens during telophase?
- Chromatids reach opposite poles.
- Nucleas envelope and nucleolus reforms around chromosomes.
- Spindle apparatus disintegrates.
- Cytoplasm divides to complete cell division (cytokinesis).
What are the 3 stages of the cell cycle?
Interphase
Nuclear division
Division of cyctoplasm (cytokinesis)
How can we remember the order of the stages of mitosis?
- Prophase - (Preparation - condensing and spindle formation)
- Metaphase - (Middle - chromosomes lined up along middle of cell)
- Anaphase - (Action - chromatids pulled apart)
- Telophase - (Two - two new cells after division)
How long does a mammalian cell to undergo 1 complete cell cycle?
24 hours
What happens during anaphase?
- Spindle fibres contract to pull sister chromatids apart at the centromere.
- Chromatids move towards opposite poles.
When a chromosome (DNA) replicates, the new stand is initially joined to the old at a place called the…
centromere.
What are the advantages of reproducing via mitosis?
Only 1 parent required.
Beneficial qualities are more likely to be passed on to offspring.
A zygote is a diploid cell. What is meant by this?
A cell containing 2 complete sets of chromosomes (one from each parent)
What are the disadvantages of reproducing by mitosis?
Less variation in offspring.
Reduced ability to adapt to changing environment.
What does the diagram show?
Interphase
Describe a cell that is in interphase
Cell is actively synthesising proteins
DNA replication
Chromosomes are invisible
why do you take cells from the root tip when studying mitosis?
Region where mitosis/cell division occurs;
When when studying mitosis do you firmly squash the root tip?
To allow light through / make tissue layer thin;
A cell under goes mitosis, the first division takes 24 hours and each subsequent one takes 8hours, how many cells are there after 3 days?
128
How can you tell a cell has just under gone DNA replication?
Chromosomes are visiable as X shaped structures - 2 sister chromatids joined by a centromere
During a root tip experiment why do we use the first 5mm of the root tip?
where the cells are under going mitosis
during a root tip experiment why do we press firmly down on the cover slip?
make it single layer of cells SO light can pass through
when counting cells during a root tip experiment - how can we be sure the mitotic index we calculate is accurate?
Look at many cells
to ensure it is representative
when growing bacteria, equipment must be sterile before use - suggest a way of sterilising equipment and why this is important?
boil in water/autoclave/wash in disinfectant
to kill bateria thay may contaminate
