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Cell Division Chapter 3 Section 3

There are over 100 trillion cells in the body! We all started out as a single cell, so how did we get so many???? Through a process of cell division.

Mitosis & Cell Division

Parts of a chromosome (pg. 105) Chromosomes are structures in the nucleus that contains DNA, the hereditary material of life. Draw and label on back of booklet.

How do cells divide? By going through the cell cycle. The cell’s life cycle is called the cell cycle. The amount of time for this is different for different types of cells.

Cell cycle

Why is this important? This is important for growth. This is important for repair. This is important for replacement of cells. Some one-celled organisms reproduce by cell division. Write this: Cell Cycle is important for: *Growth *Repair *Reproduction

Cell Cycle

What is it? The cell cycle is the “life cycle” of the cell. It occurs in phases that include periods of regular cell function and periods of cell division. It happens in all somatic (body) cells.

What is it?

interphase Cells spend 90% of its time in this phase. What happens? Cells spend 90% of its time in this phase. Performs normal functions Grows Chromosomes are copied/doubled Prepares for cell division

interphase What happens?

mitosis

What is it? Mitosis is the cell division stage of the cell cycle in which one mother cell creates two identical daughter cells. It happens in all somatic (body) cells.

What is it?

prophase Mitosis begins: Nuclear membrane dissolves What happens? Mitosis begins: Nuclear membrane dissolves Centrioles move to the opposite ends of cell (poles) Spindle fibers form and attach pairs Chromosomes pair up, condense and appear visible

prophase What happens?

metaphase What happens? Chromosome pairs line up at the center of the cell (equator). Spindle fibers attach to the chromosomes at the centromeres. Think: Meets in the Middle

metaphase What happens?

Anaphase What happens? Chromosome pairs (sister chromatids) separate and move to opposite ends of the cell. Think: move Away from the center

Anaphase What happens?

Telophase Two new nuclei form Chromosomes change to chromatin What happens? Two new nuclei form Chromosomes change to chromatin (Threads rather than rods) Mitosis Ends Think: Two new nuclei

Telophase What happens?

cytokinesis The cytoplasm splits in two Cell division is complete What happens? The cytoplasm splits in two Cell division is complete Different process for plants: Cell wall forms in the center between the nuclei Animals: cell membrane pinches in

cytokinesis What happens?