5 Cell division Flashcards
What needs to happen in most parts of the body in terms of cells?
In most parts of the body, cells need to divide so that organisms can grow and
replace worn out or damaged cells.
What should the cells produced in this cell division be like?
The cells that are produced in this type of cell division should be exactly the same as the cells they are replacing.
Does this kind of cell division happen frequently?
This is the most common form of cell division.
Where is cell division different?
In the sex organs.
How is cell division different in the sex organs?
Here, some cells divide to produce gametes (sex cells), which contain only half the original number of chromosomes.
Why do they only have half the number of chromosomes?
This is so that when male and female gametes fuse together (fertilisation) the resulting cell (called a zygote) will contain the full set of chromosomes and can then divide and grow into a new individual.
What is a zygote?
It is a single cell resulting from fusion of a male and female gamete.
What are human body cells?
They are diploid.
What does diploid mean?
It is the number of chromosomes found in body cells. Diploid cells contain both chromosomes of
each homologous pair.
What kind of cells are gametes?
Haploid cells.
What does haploid mean?
It is the number of chromosomes found in gametes. Haploid cells contain one chromosome from each homologous pair.
What are the two types of cell division?
- Mitosis.
- Meiosis.
What is mitosis?
It is a type of cell division that produces diploid body cells for growth and repair of tissues.
What are the characteristics of mitosis?
When cells divide by mitosis, two cells are formed. These have the same number and type of chromosomes as the original cell.
When is mitosis used as a cell division?
Mitosis forms all the cells in our bodies
except the gametes.
What is meiosis?
It is a type of cell division that produces haploid cells (gametes).
What are the characteristics of meiosis?
When cells divide by meiosis, four cells are formed. These have only half the
number of chromosomes of the original cell.
When is meiosis used as a cell division?
Meiosis forms gametes.
What happens during mitosis to produce ‘daugher’ cells?
When a ‘parent’ cell divides it produces ‘daughter’ cells.
What kind of daughter cells do mitosis produce?
Mitosis produces two daughter cells that are genetically identical to the parent cell.
What do we mean by the daughter cells being genetically identical?
Both daughter cells have the same number and type of chromosomes as the parent cell.
What must be done during mitosis for the daughter cell to be genetically identical to the parent cells?
- It must copy each chromosome before it divides. This involves the DNA
replicating and more proteins being added to the structure. Each daughter
cell will then be able to receive a copy of each chromosome (and each
molecule of DNA) when the cell divides. - It must divide in such a way that each daughter cell receives one copy
of every chromosome. If it does not do this, both daughter cells will not
contain all the genes
What are the four different stages of mitosis?
- Prophase.
- Metaphase.
- Anaphase.
- Telophase.
What is a diagram of what happens in the prophase?