Understanding Cell Growth and Division: Chromosomes, Mitosis, and Cell Cycle

1. Cell Growth & Division Chapter 10

2. 10-1: Cell Growth • Does an animal get larger because each cell increases in size or because it produces more of them? • In most cases, living things grow by producing more cells • Identify the problems caused by growth of cells OBJECTIVES

4. Chromosomes • Chromosomes are made of DNA (genetic information) and proteins (histones) • The cells of every organism have a specific number of chromosomes • Fruit flies = 8, human = 46, carrots = 18 • Chromosomes are not visible in most cells except during cell division • Each chromosome consists of two identical sister chromatids which separate during cell division • Each pair of chromatids is attached in an area called the centromere

5. Mitosis App Please use headphones.

6. Limits to Cell Growth • The larger a cell becomes, the more demands a cell places on its DNA • If extra copies of DNA are not made, an “information crisis” would occur • The cell also has more trouble moving nutrients and wastes across the cell membrane • Food, oxygen, water, and wastes move through the cell membrane

7. 10-2: Cell Division • Each cell has only one set of genetic information • must be copied before cell division begins • The first stage, division of the cell nucleus, is called mitosis • The second stage, division of the cytoplasm, is called cytokinesis • Reproduction by mitosis is classified as asexual

8. The Cell Cycle • Interphase is the period in between periods of cell division • The cell cycle is the series of events that cells go through as they grow and divide • During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again • The cell cycle consists of four phases • M, S, G1, and G2

9. The Cell Cycle

10. The Cell Cycle

11. Mitosis

12. Mitosis

13. Cytokinesis • Cytokinesis is the division of the cytoplasm itself and usually occurs at the same time as telophase • In most animal cells, the cytoplasm is drawn inward until the cytoplasm is pinched into two nearly equal parts • In plants, a structure known as the cell plate forms midway between the divided nuclei

15. Cytokinesis in Animal Cells

16. 10-3: Regulating the Cell Cycle • Not all cells move through the cell cycle at the same rate • The cells of the skin, digestive tract, and bone marrow grow and divide rapidly throughout life • How is the cell cycle regulated? • How are cancer cells different from other cells? OBJECTIVES

17. Controls on Cell Division

18. Cell Cycle Regulators • Proteins called cyclins - seemed to regulate the cell cycle • Proteins that respond to events inside the cell are called internal regulators • External regulators respond to events outside of the cell

19. Uncontrolled Cell Growth • Cancer is a disorder in which some of the body’s own cells lose the ability to control growth • They divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues • Causes include smoking, radiation, and viral infections

22. Uncontrolled Cell Growth