Mitosis Flashcards
What is interphase
Prepares to divide
The cells DNA is unravelled and replicated, to double its genetic content. The organelles are also replicated, it’s ATP content is increased ( ATP provides the energy needed for cell division)
Chromatin ( threads of DNA) not easily visible
DNA his tones and centrioles are replicated
Replicate organelles
More ATP made
Histones are globular proteins that DNA threads coil around
When they condense centrioles- T shaped protein structures from which spindle fibres arise.
Replicate organelles
More atp made
The structure of chromosomes
As mitosis begins, the chromosomes are made of two strands joined in the middle by a centromere. The separate strands are called chromatids .
Two strands on the same chromosome are called sister chromatids.
There are two strands because each chromosome had already made an identical copy of itself during interphase. When mitosis is over, the chromatids end up as one strand chromosomes in the new daughter cells.
Prophase
The chromosomes condense and get shorter and fatter and are visible.
Protein called centrioles start moving to opposite ends of the cell - the poles
Forming a network of protein fibres across it called the spindle.
Nucleolus disappear
Nuclear envelope breaks down and chromosomes lie free in the cytoplasm.
Metaphase
The chromosomes each with two chromatids line up along the equator of the cell and become attached to the spindle by their centromere.
Nuclear envelope disappears
Anaphase
Centromeres divide separating each pair of sister chromatids
Chromatids are pulled to opposite poles by spindle fibres, centromere first this makes the chromatids appear v shaped
Telophase
The chromatids reach the opposite poles on the spindle.
They uncoil and become long and thin again. They’re now called chromosomes again.
A nuclear envelope forms around each group of chromosomes so there are now two nuclei.
Nucleoli form
Spindle fibres disappear.
Cytokenesis
The cytoplasm divides and there are now two new daughter cells that are genetically identical to the original cell and to each other.
Mitosis is finished and each new daughter cell starts the interphase part of the cell cycle to get ready for the next round of mitosis.
In animal cells a ring of actin forms around the equator if the cell. It then tightens to form a cleavage furrow which splits the cell in two.
In plant cells vesicles move to the equator, line up and fuse to form two new membranes
New cell walls are laid down in between the two membranes and two daughters cells are produced
What are the two new daughter cells like
The two new daughter cells are genetically identical
