Transcript 5-1
Chapter 5 Lecture Notes 5-1 Cell Growth & the cell cycle As a cell double in diameter it’s surface area increases by four while it’s internal volume increases by eight. Cell Size Volume (LxWxH) Surface Area (# of surfaces xLxH) Surface Area/Volume Ratio 1cm lcm x lcm x lcm = lcm3 6 x lcm x lcm = 6cm2 2cm 2cm x 2cm x 2cm = 8cm3 6 x 2cm x 2 cm = 24cm2 6cm2/lcm3 =6/cm 24cm2/8cm3 = 3/cm Cell Cycle In most cases > a cell will increase in size > then divides into two cells. This process is a regular series of events called the cell cycle. The cell cycle is the period of time from the beginning of one cell division to the beginning of the next. Cell Cycle Consist of 4 phases: G1 Most of the cells growth and activity S Chromosome replication takes place G2 Final preparations for cell division M Cell Divison takes place (Mitosis) Cell Division is the process in which the cell divides into two independent cells called daughter cells. Daughter cells are the end result of cell division. Cancer Uncontrolled cell growth Cell Cycle Graphics drawn by Jacob Rondinella 5-2 Cell Division - In prokaryotic (lacks nucleus) the cell divides by simple division. (Binary Fission) -In Eukaryotic cells, division is more complex Interphase Makes up the G, S, + G2 phases of the cell cycle. Occurs between cell division. Chromosomes are not visible. 1. Chromosomes unfold Mitosis (cell division) Prophase MetaPhase Anaphase Telophase Prophase 1. Longest phase 2. Chromosomes appear 3. Each chromosome consists of two identical strands called sister chromatins that are attached at an area called the centromere. 4. Centrioles separate and more to opposite sides of the nucleus. Metaphase 1. Shortest phase 2. Chromosomes line up in the center of the cell. Anaphase 1. Sister chromatids split at the centromere an move towards opposite ends of the cell. 2. Anaphase stops when the chromosomes stop moving. 3. Cytokinesis begins. Telophase 1. Chromosomes start to spread out. 2. Nuclear membranes form around each cluster. 3. Cytokinesis is still happening. Cytokinesis 1. Division of the cytoplasm. 2. Helps to form two new daughter cells. 46 Chromosomes in a normal cell Sperm & egg- 23 chromosomes each Chromatin DNA + Histones Chromosomes When the chromatin coils tightly Chromatids When the chromosomes replicate 5-3 Cell Specialization That specific cells are suited to carry out specific function Macrophages Cell that provides protection. Travel through the bloodstream. Fight bacteria + germs. Neurons Message carrying cell found in the nervous system. Long and then cells. They carry electrical impulses. Levels of Organization Tissue – group of cells that perform similar function. Organs – group of tissues Organ System – group of organs that perform function 5-4 Controlling Cell Cycle Cyclins regulate / Control the Cell Cycle P188 #1-12