Cell Reproduction

Chapter 4

Cell Growth and DivisionChapter 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.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

CytokinesisThe 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 formedbetween the two daughter cells, then a cell membrane forms and completely separates. 

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