2 Cell Growth and Division Chapter 4-1 Cells undergo division to:Increase in numberRepair worn out cellsReplace cells that have died
3 Cell cycle Interphase – most of the life of any cell period of growth and developmentDNA replicationgrowth and preparation for mitosisNerve and muscle cells don’t divide remain in interphaseSkin cells constantly change
4 MitosisThe process in which the nucleus divides to form two identical nuclei.It is a series of phases or steps.
5 Animal Mitosis Interphase – Nucleus can be seen DNA is replicating (making exact copies)
6 Prophase – Chromosomes visible Nucleolus and nuclear membrane fade Centrioles move to opposite end of cellSpindle fibers begin to stretch across the cell
7 Metaphase-Double strands of chromosomes line up across the center of cellAttach to a spindle
8 Centromere – place where double stranded chromosomes are held together
9 Anaphase Anaphase Centromeres divide Two strands separate Separate strands move away toward opposite ends of cell
10 Telophase Centrioles and spindles disappear Chromosomes stretch out and become harder to see
11 Nuclear membrane forms around each mass of chromosomes New nucleolus appearsCell begins to split by pinching at cell membrane
12 Daughter cells – new cells that divided from a parent cell Interphase
18 Results of Mitosis Two Important results of mitosis: Nucleus was dividedTwo new nuclei are identical
19 CytokinesisThe period of the cell cycle when the cell separates into two daughter cellsAnimal cell cytokinesis – cell membrane pinches in the middle and a new membrane is formedPlant cell cytokinesis – cell wall is formed between the two daughter cells, then a cell membrane forms and completely separates. .