Mitosis

Biology I G/T

Why do cells divide?

• To make a new organism• Growth• Repair• Replacement of normal cell loss• Development

Structure of the Mitotic Chromosome Showing Sister Chromatids, Centromeres, and Spindle Fiber Attachment

Chromatid – ½ of a chromosome

Sister chromatid – each half of the same chromosome – they are identical

Centromere – complex of proteins attached to DNA holding the sister chromatids together

Stages of Mitosis

Interphase

S Stage

Interphase Interphase is not part of mitosis

– it is the time between cell divisions

Interphase includes G1, S, and G2

During interphase the cell is doing its normal metabolic activities like protein synthesis

The cells are performing their duty as part of a tissue

The DNA duplicates to get ready for mitosis

The DNA is in chromatin form

Animal Cell

Plant Cell

Prophase

Prophase The chromatin begins to

condense into chromosomes and become visible in the nucleus

The nuclear membrane begins to break down

Centrosomes duplicate, form spindles, & move to the poles

Spindle fibers attach to the chromosomes begin moving

Animal Cell

Plant Cell

Metaphase

Metaphase

The chromosomes are lined up down the equator by the spindles

Animal Cell Plant Cell

Anaphase

Anaphase

The sister chromatids separate at the centromeres

Each chromatid (now called a chromosome) heads to the pole of the cell Animal Cell

Plant Cell

Telophase

http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase The chromosomes are

completely to the opposite poles

New membranes start to form around the DNA

The chromosomes begin to decondense back to chromatin

Cytoplasm begins to pinch in animal cells and a cell wall begins to form in plant cells – This is cytokinesis

Animal Cell

Plant Cell

Interphase

After telophase is complete, the cells reenter interphase and go about their normal business

The DNA is totally decondensed, new nuclei reformed, and there are totally 2 new cells

Differences Plant vs. Animal Cell Mitosis

Plant cells do not have centrioles in their centrosomes but animal cells do ?????

Plant cells cannot pinch in due to the cell wall – a new cell wall forms down the middle from the endoplasmic reticulum

Plant cells divide slower due to having to reform the cell wall

Cytokinesis in an animal cell

Cytokinesis in a plant cell

plant mitosis fluorescent animal cell mitosis

animal cell mitosis

Mitosis Quiz – Animal Cells

MetaphaseInterphase

Interphase

Anaphase

TelophaseProphase

Mitosis Quiz – Plant Cells

http://biology.nebrwesleyan.edu/benham/mitosis/

MetaphaseTelophase

Anaphase

Interphase

ProphaseInterphase