Standard S7L2 a. Students will explain that cells take in nutrients in order to grow and divide and to make needed materials.

Standard S7L2b. Students will relate cell structures to basic cell functions.

Mitosis & Cell Division

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

Cells Division or Reproduction 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.

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. There are three parts.

First Phase of the Cell Cycle: Interphase This is the longest phase of the cell cycle. This is a period of growth and development of the cell.

Interphase

Interphase under a microspcope

Chromosomes are structures in the nucleus that contains DNA, the hereditary material of life. During interphase each chromosome is copied.

The duplicated strands are identical. are called “sister chromatids.”

The center of a chromosome is called the centromere, it joins the two chromatids together to form a chromosome.

Stop & Share Interphase & Chromosomes Interphase is the first stage of the cell cycle. Interphase is the longest phase of the cell cycle. Interphase is a period of growth and development. During interphase the chromosomes duplicate. The chromosomes are now identical sister chromatids connected by a centromere.

The nucleus divides in two ways…. Mitosis & Meiosis

Mitosis happens when body or somatic cells make exact copies of each other with the same number of chromosomes.

Prophase Nuclear membrane begins to disassemble (come apart).

Picture of Prophase

Metaphase

Mataphase under the Microscope

Anaphase

Anaphase

Telophase Nuclear membrane begins to form.

Telophase

Stop & Share Mitosis The phases of mitosis are prophase, metaphase, anaphase, and telophase. Prophase---spindle fibers form Metaphase---Spindle Fibers Attached, Middle of Cell Anaphase---Chromatids Separate; Away or Apart Telophase---Two Nuclei

Trick for Remembering Phases Interphase: Inner Growth PMAT Prophase: Poles Metaphase: Middle of Cell Anaphase: Apart or Away Telophase: Two Nuclei Finally, Cytokinesis

How do plant cells divide after mitosis? In plant cells, a cell plate forms in the middle of the cell. The cell plate divides the cytoplasm into two parts. New cell walls form along the cell plate. New cell membranes form inside the cell walls.

Cell Plate

Results of Mitosis Each cell in body has same number of chromosomes Allows growth and replacement of damaged or worn out cells. Asexual Reproduction: Binary Fission-mitosis Budding---growing from side of parent Regeneration---regrow parts

Asexual Reproduction Regeneration Budding

Bacterial Reproduction Binary Fission Reproduction for Prokaryotic Cells (Bacteria)