Cell Division This is a title slide for this presentation

Why Cells Make More Cells Slide # 2 Why Cells Make More Cells 1. Most cells go through a series of changes in order to maintain homeostasis. 2. Cells need to reproduce (divide) when their surface area can no longer supply the much larger volume with nutrients and get rid of wastes. Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume

Introduction to Mitosis Slide # 3 1. Two main stages of cell division a. Mitosis: division of the nucleus b. Cytokinesis: division of the cytoplasm 2. Produces 2 cells called daughter cells a. Cells are genetically identical 3. Mitosis is source of new cells for a. Growth b. Development c. Repair d. Replacement of old cells Normal red blood cells only live for 120 days. Then they die & stem cells make new ones. This is a title slide for this presentation

Fruit flies have 8 chromosomes in each body cell Slide # 4 1. Chromosomes: made up of DNA & proteins 2. Carry the cell’s coded genetic information 3. Different organisms have a different number of chromosomes Fruit flies have 8 chromosomes in each body cell This is a title slide for this presentation Humans have 46 chromosomes in each body cell Frogs have 26 chromosomes in each body cell

Vocabulary 1. Chromatin: the relaxed, uncoiled state of the chromosome Slide # 5 1. Chromatin: the relaxed, uncoiled state of the chromosome 2. Chromatid: one of two identical “sister” parts of a duplicated chromosome Chromosome: threadlike structures within the nucleus containing genetic information that is passed on from generation to generation 4. Centromere: chromosome region that joins 2 sister chromatids

Cell Cycle Consists of 2 phases M phase: Mitosis & Cytokinesis Slide # 6 1. Cell cycle: Sequence of events between the time a cell divides to form 2 daughter cells & the time those 2 cells divide Consists of 2 phases M phase: Mitosis & Cytokinesis Interphase G1 S G2

Mitosis Discovered Slide # 7 Walther Flemming first discovered mitosis in 1870 and reported is discovery of chromosomes and mitosis in 1882. Metaphase in a salamander cell drawn by Walther Flemming from a stained slide.

Interphase: 3 Phases 1. G1 phase: Growth Phase Slide # 8 centrioles 1. G1 phase: Growth Phase Cell performs all life’s activities: protein synthesis, waste removal, organelle synthesis, etc. 2. S phase: DNA Replication DNA makes a copy of itself Produces 2 identical sets of chromosomes 3. G2 phase: Preparation Cell produces centrioles & spindle fibers needed to move the chromosomes This is a title slide for this presentation Nucleus & duplicated chromosomes

Mitosis Described as movement of chromosomes Slide # 9 Mitosis Described as movement of chromosomes Continuous series of events Divided into four phases so that it is easier to understand Cell Cycle

Prophase: 1st Phase Slide # 10 1. Chromatin (DNA) condenses, coils, & becomes rod shaped 2. Centrioles move to opposite ends of cell 3. Spindle fibers attach to chromosomes 4. Nuclear membrane breaks down

Metaphase Slide# 11 1. Spindle fibers push & pull chromosomes until they line up across center of cell 2. Centromere of each chromosome pair is attached to a spindle fiber This is a title slide for this presentation

Anaphase 1. Spindle fibers shorten & paired chromatids separate Slide # 12 1. Spindle fibers shorten & paired chromatids separate 2. Spindle fibers pull separated chromosomes to opposite ends of the cell 3. Centromere of each pair divides; now have individual chromosomes This is a title slide for this presentation

Telophase 1. Chromosomes begin to uncoil and de –condense Slide 13 1. Chromosomes begin to uncoil and de –condense 2. Nuclear membrane reforms around each new set of chromosomes This is a title slide for this presentation

Cytokinesis 1. Cytokinesis is division of the cytoplasm Slide # 14 Cytokinesis 1. Cytokinesis is division of the cytoplasm 2. Distributes the organelles In animal cells, the cell membrane pinches together around the middle of the cell and forms 2 cells. In plant cells, a cell plate forms across the middle of the cell and new cell walls form between the daughter cells This is a title slide for this presentation

Cancer Cells Slide # 15 1. Normal cells contain check points to regulate the cell cycle, & stop at appropriate check points. 2. Cancerous cells do not respond to check points and continue rapidly through the cell cycle. This results in masses of undefined cells called tumors. 3. Cancer cells do not mature; they become more immature.

Binary Fission 1. Binary fission is the process by which all bacteria reproduce . Each resulting daughter cell is genetically identical to the parent cell. 3. Under ideal conditions, bacteria can reproduce once every 20 minutes If you start out with 1 bacterium cell, how many could be produced after 7 hours? 2, 097, 152 produced in just 7 hours!