Multicellular Organisms: Producing New Cells Flashcards
Why is mitosis important?
Provides new cells for:
- Growth
- Replacement of dead/damaged cells
- Repair of damaged tissues.
It also maintains the chromosome complement.
What does the term ‘diploid’ mean?
A cell which has 2 matching sets of chromosomes.
What are the stages of mitosis?
Stage 1: Parent cell - Chromosomes are long and uncoiled. Each chromosome is replicating to form 2 identical chromatids. Diploid cell.
Stage 2: Each chromosome has replicated and now consists of 2 chromatids. Shorter and thicker.
Stage 3: The nuclear membrane had broken down. Chromatids line up along the equator of the cell and spindle fibres attach to each pair of chromatids at the centromere.
Stage 4: Spindle fibres shorten and pull the chromosomes apart, separating them. Once separate, the chromatids are now called chromosomes.
Stage 5: A new nuclear membrane forms around each set of chromosomes. The cytoplasm then begins to divide.
Stage 6: 2 identical, diploid cells are formed. Each new cell has the same number of chromosomes as the parent cell - mitosis ensures that the chromosome complement is maintained.
What is a chromatid?
One of two identical copies making up a replicated chromosome.
What is an equator?
The place in which chromosomes line up in a cell during cell division.
What is the role of spindle fibres?
To attach to the centromere and pull the chromatids apart.
How does mitosis maintain the diploid chromosome complement?
Each daughter cell that is produced consists of the same chromosomes as the parent cell, ensuring no genetic information is lost.
What is a stem cell?
Unspecialised cells which can divide by mitosis and have potential to become different types of cells.
What type of organism are stem cells found in?
Animals
What are the two types of stem cells?
- Embryonic stem cells
- Tissue stem cells.
Where are embryonic stem cells found?
Embryos at a very early age.
Where are tissue stem cells found?
The body throughout life (fetus to death)
What are 2 functions of stem cells in humans?
- Self renewal - can reproduce through mitosis while remaining unspecialised.
- Differentiation - can differentiate when required - they can become specialised for a particular function and can no longer change into different cells.
What is a multicellular organism?
An organism with more than one cell type and are made up of tissues and organs.
Describe the organisation of multicellular organisms
Specialised cell -> tissue -> organ -> organ system -> multicellular organism
