Mitosis Flashcards
What is the cell cycle
Process of cell growth and division
What does the cell cycle compose of
Interphase and nuclear division (mitosis and cytokinesis)
What are the 4 division stages in mitosis
Prophase, metaphase, anaphase, telophase
What is the longest phase in the cell cycle
Interphase
What is mitosis needed for
Growth of multicellular organisms and for repairing tissues.
Also a method of asexual reproduction for plants, animals and fungi
What is the interphase divided into
G1, S, G2
What happens during G1
It is the first growth phase. The proteins from which the organelles are synthesised are produced and organelles replicate. The cell increases in size
What happens in the “s” phase
Synthesis phase. DNA is replicated in the nucleus
What happens in the G2 phase
The second growth phase. The cell continues to increase in size and energy stores. The duplicated dna is checked for errors
What happens in cytokinesis
The cytoplasm divides and 2 cells are produced
What happens in the stage “G0” and why does this happen
The phase where the cell leaves the cell cycle, either temporarily or permanently. Differentiation can lead to the cell leaving as a cell that is specialised is no longer able to divide. The dna may also be damaged so it has to leave the cell cycle. Age also contributes as the number of damaged cells increase
What happens in prophase
Chromosomes condense, getting shorter and thicken. Centrioles start moving to opposite ends of the cell forming a network of protein fibres called spindles. Nuclear envelope breaks down and chromosomes lie free in cytoplasm.
What happens in the metaphase.
The chromatids line up along the middle of the cell and becomes attached to the spindle by their centromere. At the checkpoint the cells checks that all the chromatids are attached to the spindle.
What happens in anaphase
The centromeres divide, separating each pair of sister chromatids. Spindle contracts pulling chromatids to opposite end of the cell
What happens in the telophase
The chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. Nuclear envelope form around each group of chromosomes so there are 2 nuclei
What happens in cytokinesis
Cytoplasm divides and a cleavage furrow forms to divide the cell membrane. There are now 2 genetically identical daughter cells
