Mitosis - Cell division http://www.youtube.com/watch?v=VGV3fv-uZYI

Living organisms have life cycles. Life cycles begin with organism’s formation, followed by growth and development and end in death.

Individual cells have life cycles. Some cells constantly complete the cycle, others take 16-20 hours or longer. Cell cycle is broken down into sections

Interphase The longest part of a cell’s life cycle Several major things occur during Interphase; The cell grows, develops. Organelles are duplicated. The DNA is copied (chromosomes duplicated) The cell prepares for cell division. Interphase is NOT part of mitosis.

Interphase

In Interphase, chromatids are duplicated. When the nucleus is ready to divide, each duplicated chromosome coils into two thickened strands called chromatids.

Mitosis Mitosis: process in which the nucleus divides to form two identical nuclei. Steps of Mitosis: Prophase, Metaphase, Anaphase, and Telophase. (PMAT)

Prophase (Prepare) First step of mitosis Chromatids are fully visible under a microscope Nucleolus and nuclear membrane disintegrate Two organelles called centrioles move to opposite ends in the cell. Between the centrioles, (only in animal cells) thin threadlike structures called spindle fibers begin to stretch across the cell.

Metaphase (Middle) The chromosomes line up across the midline of the cell. The centromere of each chromosome becomes attached to the spindle fibers.

Anaphase (Apart) The centromere, in the center of each pair of chromatids, splits in half. The spindle fibers shorten, pulling the pair of chromatids apart. Each pair of chromatids separate, and move to opposite ends of the cell.

Telophase (Two nuclei form) Spindle fibers disappear. Nuclear membrane reappears. Chromosomes begin to uncoil and a new nucleus forms.

Cytokinesis Division of the cytoplasm In animal cells – the cell membrane pinches in the middle. In plant cells – a cell plate forms followed by the formation of new cell walls . Then cells enter into Interphase to repeat the cell cycle again.

Cytokinesis Animal Cell Why doesn’t a plant cell pinch in at the sides like an animal cell? Plant Cell

Onion Root Tip Cells

Results of Mitosis Mitosis is the division of a nucleus. The process produces two new nuclei that are identical to each other and to the original nucleus.

Why does mitosis happen? Mitosis allows for: Growth Replacement of worn out or damaged cells In some organisms, it is used to produce new organisms

Asexual Reproduction A new organism is produced from one organism. The new organism has exactly the same hereditary material as the parent organism.

Asexual Reproduction in Plants

Asexual Reproduction in Animals Budding and Regeneration http://www.youtube.com/watch?v=489CSop00sY http://www.youtube.com/watch?v=f7cXeWxxfD4

Prokaryotic organisms cannot undergo mitosis (they have no nucleus) They reproduce asexually using fission

http://www.youtube.com/watch?v=VGV3fv-uZYI

What are the stages? Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Identify each stage of the cell cycle (no cytokinesis stage)

Answers Metaphase 11. Metaphase Prophase 12. Telophase Telophase Interphase Anaphase 11. Metaphase 12. Telophase 13. Interphase 14. Prophase 15. Interphase 16. Interphase 17. Metaphase 18. Interphase Which stage is the longest: Interphase