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?
- chromosomes condense (get short and fat)
- nuclear membrane breaks down
- centrioles move to opposite poles
What does the diagram show?
Telophase (leading to cytokinesis)
Describe the process of bacterial binary fission
- circular loop of dna replicates
- move to opposite ends of cell
- plasmids replicate
- cytoplams divides to = 2 identical daughter cells
- each has single copy of circular dna
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 protein binds to complementary receptor protein on host
- attachment protein specific to host receptor protein
- viruses inject genetic material
- hijacks host cells - uses host cells machinery/organelles
- to reproduce new viruses
What happens during metaphase?
- double chromosomes line up on equator
- spindle forms
- spindle attaches to centromere
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?
- nuclear membrane reforms
- cytokinesis (cytoplams divides)
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?
- centromeres split
- chromatids pulled to 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
give two pieces of evidence of a cell that is undergoing mitosis? EXPLAIN your answer
- formation of sister chromatids BECAUSE DNA has replicated
- individual chromosomes visible BECAUSE condensed
a dark stain is used on chromosomes and binds more to some areas of the chromosomes than others, giving the chromosomes a striped appearance.
suggest ways in which the structure of the chromosome could differ along its length to result in the stain binding more in some areas?
- difference in base sequence
- difference in histones
- difference in condensation
how would you calculate the percentage of cells in which chromosomes are visible and would consist of a pair of chromatids together?
- find no. of cells in prophase and metaphase & ADD together
- divide by total
- x by 100
in an investigation, a different set of results were obtained when the count was repeated on another occasion with a different garlic root tip.
give 2 reasons for the difference in results?
- genetic differences
- different day
