How does an organism produce new cells?
Mitosis and meiosis are two ways that cells reproduce
MITOSIS is the process by which a cell divides to produce two new cells with identical sets of chromosomes to the parent cell
- the new cells will also have all the necessary organelles.
- The purpose of mitosis is to produce new cells for growth and repair and to replace old tissues.
- Mitosis leads to the production of two new cells, which are identical to each other and to the parent cell.
- Mitosis can only take place when a cell is ready to divide this means that cells go through a cell cycle.
- The cell cycle consists of a growth stage (G1) where the cell gets bigger and the number of organelles increase
- then a synthesis stage (S) where the DNA is copied, followed by another very short growth stage (G2) immediately before mitosis (M)
- Both new cells need to have a full complement of organelles and DNA to function properly.
- Therefore the number of organelles needs to increase and the DNA has to be copied.
- The chromosomes are copied when the two strands of each DNA molecule separate and new strands form alongside them.
- In I/GCSE Biology, meiosis is commonly asked in the exam!
- only takes place in the testes and ovaries
- it is a special type of division that produces gametes (sex cells i.e. eggs and sperm) for sexual reproduction.
Gametes contain half the number of chromosomes of the parent cell
- this is important because it means that when the male and female gametes fuse
- the number of chromosomes will increase back to the full number.
- The resulting zygote has a set of chromosomes from each parent.
And we're done with this topic! Well Done!
Drafted by Alyssa (Biology)
- "Cell cycle". Photo from the internet.
- "The Stages of Mitosis and Cell Division", https://www.thoughtco.com/thmb/8CyVFro_VKP9-LrVMm9oKhLQWu4=/1500x1000/filters:fill(auto,1)/stages-of-mitosis-373534-V5-5b84992cc9e77c00574f03d3.png
- "Cell cycle", https://pic.pimg.tw/stu60116/1622344315-1640027447-g.png
- "Meiosis", https://biologydictionary.net/wp-content/uploads/2016/12/Meiosis-Stages.jpg
- "Meiosis". Photo from the internet.