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.