Cell Reproduction Chapter 4

Cell Growth and Division Chapter 4-1 Cells undergo division to: Increase in number Repair worn out cells Replace cells that have died

Cell cycle Interphase – most of the life of any cell period of growth and development DNA replication growth and preparation for mitosis Nerve and muscle cells don’t divide remain in interphase Skin cells constantly change

Mitosis The process in which the nucleus divides to form two identical nuclei. It is a series of phases or steps.

Animal Mitosis Interphase – Nucleus can be seen DNA is replicating (making exact copies)

Prophase – Chromosomes visible Nucleolus and nuclear membrane fade Centrioles move to opposite end of cell Spindle fibers begin to stretch across the cell

Metaphase- Double strands of chromosomes line up across the center of cell Attach to a spindle

Centromere – place where double stranded chromosomes are held together

Anaphase Anaphase Centromeres divide Two strands separate Separate strands move away toward opposite ends of cell

Telophase Centrioles and spindles disappear Chromosomes stretch out and become harder to see

Nuclear membrane forms around each mass of chromosomes New nucleolus appears Cell begins to split by pinching at cell membrane

Daughter cells – new cells that divided from a parent cell Interphase

Mitosis                                       

Mitosis in Plant Cells All phases are the same as animal cells Telophase Cell wall is produced to separate the cells.                                       

http://www. biology. arizona http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html

Identify each phase of mitosis below.

Identify animal mitosis

Results of Mitosis Two Important results of mitosis: Nucleus was divided Two new nuclei are identical

Cytokinesis The period of the cell cycle when the cell separates into two daughter cells Animal cell cytokinesis – cell membrane pinches in the middle and a new membrane is formed Plant cell cytokinesis – cell wall is formed between the two daughter cells, then a cell membrane forms and completely separates.  .