220 likes | 377 Views
Chapter 10 Notes. Cell Growth and Division. I. The Cell Cycle. Interphase: the portion of the cell cycle between divisions 1. About 75 – 80% of the life of the cell 2. 3 phases: a. G 1 : cells grow and develop b. S: chromosomes replicate.
E N D
Chapter 10 Notes Cell Growth and Division
Interphase: the portion of the cell cycle between divisions 1. About 75 – 80% of the life of the cell 2. 3 phases: a. G1: cells grow and develop b. S: chromosomes replicate
1. Duplicated chromosomes are called sister chromatids 2. Sister chromatids attach at a point called a centromere 3. Chromosomes are now “double stranded”
sister chromatids centromere
Cell Division: cell divides into 2 daughter cells 1. Mitosis: division of nucleus Click for overview of mitosis
a. Prophase 1. Chromosomes become visible 2. Nuclear membrane breaks down; nucleolus disappears 3. Spindle begins to form
b. Metaphase 1. Chromosomes line up in the center of the cell 2. Spindle fibers attach to sister chromatids at the centromere
c. Anaphase 1. Sister chromatids separate into individual chromosomes 2. Chromosomes are pulled apart to opposite ends of the cell
d. Telophase: 1. New nuclear envelopes form; nucleolus reappears 2. Spindle breaks down
2. Cytokinesis: division of the cytoplasm a. In animal cells, cell membrane pinches inward:
II. Regulating the Cell Cycle • Proteins called cyclins stimulate division during growth and repair • Uncontrolled cell growth can lead to cancer 1. Some causes: heredity, chemicals, radiation
2. Cancer cells do not respond to signals that regulate growth 3. Cells grow unregulated leading to tumors a. Benign: cells stay together
b. Malignant: cells spread and grow elsewhere - invade healthy tissues - lack surface proteins which cause them to stick together