Stages of Mitosis
During__ __mitosis, cells divide to produce two new ones which are exact copies of the original cell.
Two__ __daughter cells are produced from the parent cell.
Each daughter cell has 46 chromosomes.
All body cells divide by the process of mitosis, and are therefore identical to their parent cell. The only cells in the human body that do not undergo mitosis are the gametes, or sex cells __(__egg and sperm) which undergo a different process called meiosis. Egg and sperm cells each only have 23 chromosomes.
When a cell is growing and dividing, it will go through the cell cycle:
- The cell is growing
- Synthesis of DNA (the single strand of DNA will copy itself)
- Further period of growth occurs where the DNA is checked for errors
- Once the errors have been checked for, mitosis takes place
- In the end, two identical cells are formed
Here are the stages of mitosis in a diagram:
Important of Mitosis
Mitosis is needed for __repair __and __replacement __of cells:
- at site of wound or injury
- during growth spurts
- during production of red blood cells in bone marrow (happens all the time)
- takes place rapidly when an egg is newly fertilised, as the egg grows bigger as it develops further
The human body is constantly undergoing mitosis as it is needed to grow and replace old and damaged cells.
Unfortunately, cells can start to divide uncontrollably, even when the body does not need them. The production of new cancerous cells may produce tumours.
Benign tumours normally grow quite slowly through a membrane, therefore it can be removed quite easily. Benign tumours don’t tend to grow back, and they do not spread to other body parts.
On the other hand, malignant tumours are cancerous and they tend to grow quickly. It can spread to other body parts in the bloodstream.
Growth in Organisms
Growth takes place in both animals and plants.
In order for plants and animals to develop from a single cell, they must divide through mitosis in order to produce a__ __multicellular organism.
Cells will differentiate as they continue to divide, grow and develop. These cells are different from the original cells, as they become specialised into different functions. These specialised cells would then work together in order to enable the multicellular organism to function.
Where does mitosis occur?
- Mitosis happens throughout all body cells in animals
- It only happens in the meristems for plants. Meristems can be found in the tip of roots and shoots. These are the places where new cells can be formed. Cell elongation takes place throughout the plant, and this enables the plant to become longer as they grow.
Animals have complex systems that include a range of organs that work together in order to allow an organism to function:
- The respiratory system is vital in allowing an organism to breathe.
- The reproductive system is vital in producing the appropriate cells needed for fertilisation so that new offsprings can be created.
- The muscular system is vital in bringing about movement.
Plants also have specialised cells which allow them to function and survive:
- The phloem transports products made from photosynthesis from the leaf to where it is required.
- Guard cells can be found on the bottom of the leaf as it opens and closes in order to control the exchange of gases as it alters the rate of transpiration.
- How many chromosomes can be found in a daughter cell (in humans)
Explanation: There are 23 pairs of chromosomes in human body cells - therefore 46 chromosomes in total
- What are the two types of cancer cells?
- Your answer should include: Benign / Malignant
- Why is mitosis so important?
- Your answer should include: growth / repair / replacement
Explanation: So that cells can grow, repair and replace damaged or old cells.