cell division, mitosis and meiosis

the process by which a cell reproduces itself

• normal growth
• development
• repair

before dividing it makes a copy of its contents so that each new cell has the same amount of organelles, DNA, and cytoplasm as the original cell

ordered sequence of stages that a cell progresses through in order to divide during its life

• preparatory stages G1 S G2
• division stages (mitosis and cytokinesis)

• the preparatory phases of cell divisioncell makes a copy of the DNA, and produces more organelles and cytoplasm
• includes G1, S, and G2

the sister chromatids of each chromosome are separated from one another, setting up the 2 identical nuclei of the daughter cells

cell grows and prepares to divide both its DNA and its organelles

• DNA replication occurs
• chromosomes are duplicated during this phase

cell prepares for division

• one of the 2 identical DNA molecules that make up a duplicated chromosome following DNA replication
• joined together at a region of the chromosome known as the centromere
• during mitosis and cytokinesis, they pull apart and move into separate daughter cells

• the cytoplasm divides into 2 cells, each containing a full complement of organelles and DNA
• cell membrane pinches in to completely surround each new daughter cell

• 1 prophase
• 2 prometaphase
• 3 metaphase
• 4 anaphase
• 5 telophase

• replicated chromosomes begin to coil up
• nuclear membrane begins to disassemble
• protein fibers of the mitotic spindle begin to form

• chromosomes condense to shorten them, making it easier to separate
• spindle fibers attach to chromosomes on both sides at the centromere region

• spindle fibers from opposite ends of the cell pull on chromosomes
• chromosomes are aligned along the middle of the cell

spindle fibers shorten and pull sister chromatids to opposite ends of the cell

• identical set of chromosomes reaches each pole
• spindle fibers dissemble
• nuclear membrane forms around each set of chromosomes, forming the daughter cell nuclei

2 identical daughter cells are formed, each with the same number of chromosomes as the parent cell

system of checkpoints to prevent a cell from progressing to the next stage of division until it accurately finishes the current stage

programmed cell death to prevent cells from producing more damaged daughter cells

disease of unregulated cell division

damaged checkpoint mechanisms - allows them to divide when they shouldn't and bypass apoptosis, passing damaged DNA to daughter cells