Chapter 10 Cell Growth & Division
10-1 Cell Growth • Question: Are cells in a mouse and a whale the same size?? • INTEREST GRABBER (10-1) • The larger a cell becomes, the more demands the cell places on its DNA. In addition, the cell has more trouble moving enough nutrients and wastes across the membrane
Limits to Cell Growth • DNA “overload” • DNA is unable to meet needs of a large cell • Surface area to volume ratio • Volume increases more rapidly than surface area • Exchanging Materials • The rate at which oxygen, food, & waste are used up depends on the cell’s volume • The rate at which oxygen, food, & waste diffuse across the membrane depends on the cell’s surface area
Division of the Cell • Before cells become too big, they divide forming two “daughter” cells. • The process of division is called cell division.
10-2 Cell Division • In eukaryotic cells, genetic information is passed on from one generation to the next by chromosomes. • Chromosomes are made of DNA • Human cells have 46 chromosomes
Purposes of Mitosis • Reproduction of unicellular organisms • Types of asexual reproduction • Growth / repair in multicellular organisms
The Cell Cycle • The cell cycle is a series of event that cells go through as they grow and divide. • During the cell cycle, a cell … • Grows • Prepares for division • Divides to form 2 daughter cells • Each of which begin the cell cycle again!!
Events of the Cell Cycle • Interphase • Has three phases: G1, S, and G2 • Cell Grows • Chromosomes replicate
MITOSIS • Prophase • Longest Phase • 50 – 60% of the total time of Mitosis • Spindle Fibers Form • Nuclear Envelope Disappears • Chromosomes Coil up more tightly
2) Metaphase Chromosomes line up across the center of the cell
3) Anaphase • Sister chromatids separate and move to opposite ends of the cell
4) Telophase • Chromosomes uncoil • Nuclear Envelope reappears • Spindle fibers disappear
Cytokinesis • Splitting of the cytoplasm into two cells!
10-3 Regulating the Cell Cycle • READ pages 250 – 253! • Answer the following questions in your JOURNAL: • What is Cancer and what causes it? • Can cell division be turned on and off? • What does Cyclin do? • What are stem cells? • Do you believe stem cell research should be allowed? Briefly support your answer