Download Ch. 22 Cell Reproduction

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What two (2) reasons do
you think cells divide?
Ch. 10
Cell Growth and
Reproduction
Why do cells divide?
Body Growth and Repair
• All living things grow
• All living things need to repair themselves
when injured
• New cells are made to make these two
things happen
• The process of making new cells is called
MITOSIS
Cell Cycle
• The life of a cell is called the cell cycle
• It has five main phases
– G1: this phase is for GROWTH and making new
organelles.
– S phase: this phase for SYNTHESIZING
chromosomes.
– G2: this phase is a second GROWTH phase dedicated
to growing in size to prepare for cell division.
– Mitosis: process of cell division
– Cytokinesis: the end process of one cell becoming
two cells
Mitosis
• Done in all the body cells of living things
• Makes a copy of original cell
• Done in four steps
–Prophase
–Metaphase
–Anaphase
–Telophase
Prophase
1. Sister chromatids begin to shorten
2.
3.
4.
and thicken into chromosomes
Nuclear membrane begins to break
down
Centrioles move to the poles of the
cell
Spindle fibers form from each
Centriole towards the center of the
cell
Metaphase
1. Centrioles are at opposite side of
the cell
2. Chromosomes line up in the
middle of the cell
3. Spindle fibers attach to the
centromere of the chromosome
Anaphase
1. Chromosomes are pulled apart
2. Spindle fibers disintegrate after
chromosome passes
3. Chromosomes are pulled towards
the centrioles
Telophase
1. Each side of the cell has a
complete set of chromosomes
2. The cell starts to pinch in to split
3. Nucleus starts to reappear
4.
CYTOKINESIS
• At the very end of mitosis
cytokinesis occurs
• “Cyto”- meaning cell
• -”kinesis” process of making new
Correctly identify the following
phases of the cell cycle.
• Each number on the following picture
represents a phase of the cell cycle
• in you do now for the week place the
correct name of the phase for each
number.
2
1
3
4