6.2 Mitosis Flashcards
What is mitosis necessary for
When daughter cells need to be identical for growth replacement and repair of tissues in multicellular organisms
Asexual reproduction
What is teh structure of a chromosome
2 chromatids joined together at the centromere
What are the 4 stages of mitosis
Prophase
Metaphase
anaphase
Telophase
How can you obtain dividing cells
Growing root tips of plants
They are treated with a chemical to seperate the cells
Then they’re squashed to form a single layer on a microscope slide
What happens in prophase
Chromatin fibres begin to foil and condense to form chromosomes
Nucleolus disappears
Nuclear membrane begins to break down
Microtubules form spindle shaped fibres and surround teh cell these are attached to the centrioles
2 centrioles migrate to opposite sides of the poles and spindle fibres attach to centromeres and move chromosomes to centre of cell
What happens during metaphase
Chromosomes are moved by spindle fibres to form a plane on the metaphase plate
The spindle assembly checkpoint takes place here
What happens in anaphase
Centromeres holding the pairs of chromatids divide
So chromatids are separated and pulled to opposite poles of teh cell by the shortening spindle fibres
What happens in telophase
Chromatids reaches the opposite poles
Chromatids are now called chromosomes
Two new sets of chromosomes assemble and the nuclear envelope reforms around them
Chromosomes start to uncoil and nucleoulus Is formed
What happens after just telophase
Cytokinesis
Actual division of the cell into 2 seperate cells
What happens to animals cells when they go through cytokinesis
A cleavage furrow forms around the middle of the cell
Membrane is pulled inwards by cytoskeleton
How do plants go through cytokinesis
Have cell walls so not possible for cleavage furrow to form
Vesicles begin to assemble where the metaphase plate was
Vesicles dude with each other and membrane dividing the cell into 2
