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Biology
Cell Reproduction Notes
New cells are created in your body every day. Think of three reasons why your body might need new cells.
Unicellular organisms - asexual reproduction
Multicellular organisms- growth & repair.
M phase
G2 phase
S phase
G1 phase
Figure 10–4 The Cell Cycle
Section 10-2
Cell Cycle
• Interphase - the longest part of the cell cycle: growth, metabolism & preparation for division occurs. Chromosomes are replicated. (S phase)
• Mitosis- the division of the nucleus.
• Cytokinesis - the division of the cytoplasm.
The Steps of Mitosis
• PMAT (remember the order that they occur)
• Mitosis produces two cells with the same number of chromosomes.
Prophase(Preparing)
• Longest phase of mitosis
• Nuclear envelope & nucleous disappears.
• Chromosomes become visible.
• Centrioles (animal cell) form and move to opposite poles of cell
• Spindle fibers form from centrioles, cross cell and attach to the chromosomes.
Metaphase(middle)
Chromosomes line up in the middle of the cell.
Spindles are attached to them.
Anaphase(Apart)
• Spindle fibers begin to shorten.
• This pulls chromosomes apart.
• Chromosome halves are now referred to as chromatids.
Telophase(Two cells)
• Chromatids reach poles.
• Chromosomes become chromatin.
• Spindle fibers break down.
• Nucleolus and nuclear envelope appear.
Cytokinesis (happens during telophase)
• Division of cytoplasm• In animal cells: cell
membrane continues to pinch in until two cells are formed
• In plant cells: cell plate forms in center of cell and eventually splits cells
• At the end of mitosis, two new “daughter” cells are produced.