Unit 2 Flashcards
What do we need mitosis for
Growth
Repair
Step 1 of mitosis
The chromosomes line up along the equator of the cell and rope like structures called spindle fibres attach to the middle of each chromosome.
Step 2 of mitosis
The spindle fibres pull the chromatids apart and chromosomes move to opposite parts of the cell.
Step 3 of mitosis
The nuclear membrane reforms and for a brief period there is now one cell with two nucleus
Final step of mitosis (step 4)
The cytoplasm divides and 2 identical daughter cells are formed these daughter cells are both diploid with the same dna as the cell in the beginning
What are stem cells
Stem cells are unspecialised cells. They are needed for growth and repair
What are the two things stem cells can do
Self renew (to make more stem cells)
Become specialised (to replace or renew existing specialised cells)
What are the two types of stem cells
Embryonic stem cells
Tissue stem cells
Features of embryonic stem cells
Found only in embryos and can specialise into any human cell
Features of tissue stem cells
Only found in adults and can specialise into a few different cells
Meaning of multicellular
An organism made up of more than one cell
Is bacteria multicellular
No, they are unicellular
The hierarchy of cell organisation
Specialised cell—>tissue—>organ—>system—>organism
What is a diploid cell
A diploid cell has two matching sets of chromosomes.
Why do cells become specialised
To produce a variety of cells that have a particular function
