Chapter 9 Cell Growth PDF

Cell Growth and Division 1  Objectives 1. Name the main events of the cell cycle 2. Describe what happens during the four phases of mitosis 3. Identify a factor that can stop cells from growing 4. Explain how cancer cells are differ...

Cell Growth and Division 1  Objectives 1. Name the main events of the cell cycle 2. Describe what happens during the four phases of mitosis 3. Identify a factor that can stop cells from growing 4. Explain how cancer cells are different from other cells 2 Living organisms are distinguished by their ability to reproduce their own kind Genetics is the scientific study of heredity and variation Heredity is the transmission of traits from one generation to the next Variation is demonstrated by the differences in appearance that offspring show from parents and siblings 3  In unicellular organisms, division of one cell reproduces the entire organism Paramecium Escherichia coli Pirococcus furiosus Closely related to Eukarya and us… and algae, and moss, and amoebas. It grows between 70 °C and 103 °C, 4  Multicellular organisms depend on cell dividing for: Development of a fertilized cell Growth Repair Cell’s dividing is an integral part of the cell cycle, the life of a cell from formation to its own division 5  A growing cell divides forming two.. daughter cells The process by which a cell divides into two daughter cells is called Cell Division They are identical 6  Genetic information is passed from one generation to the next on chromosomes. Chromosomes are only visible during cell division Chromatin Before chromosomes are visible they are called.. 7 Before the DNA coils up, it is copied The two exact copies of DNA that make up each chromosome are called... Sister Chromatids 8  During cell division the “sister” chromatids separate from each other This ensures that each cell will have the Cell same genetic information as the original cell. Cell 9  Each pair of chromatids is attached at an area called.. Centromeres Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. Baby cell 10  Stages of Eukaryotic cell division: 1. Mitosis--- My The nucleus of the cell is divided into two nuclei 2. Cytokinesis--- The cell’s cytoplasm divides 11  During the cell cycle: 1) a cell grows 2) prepares for division 3) divides to form two daughter cells, each of which begins the cycle again 12 The cell cycle consists of four phases: G1 (First Gap Phase) S Phase G2 (Second Gap Phase) Cell division Phase 13 A cell spends 90% of its time in the first three phases, which is collectively called... Interphase G1 phase the cell grows rapidly and carries out its routine functions synthesize new proteins and organelles. 14  S phase/synthesis 1. the cell’s DNA is copied 2. The cell Centrioles are copied At the end of this phase, there are two more centrioles 15  G 2 phases Preparations are made for the nucleus to divide. Organelles and molecules required for cell division are produced When G2 phases is complete the cell is ready to enter the... M Phase of Cell division 16  M Phase of Cell Division Biologists divide the events of mitosis into four phases: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase 17 1. Prophase Prophase is the first and longest phase of mitosis. G2 of Interphase Prophase Centrosomes Chromatin Early mitotic Aster Centromere (with centriole (duplicated) spindle Centrioles pairs) Nucleolus Nuclear Plasma Chromosome, consisting envelope membrane of two sister chromatids (A) Two structures made of microtubules separate and take up positions on opposite sides of the nucleus. (B) centrioles form spindle fibers 18 1 Prophase Spindle forming (C) Chromatin condenses into chromosomes. Chromosomes are now visible Centromere (D) The nuclear envelope breaks down. Chromosomes (paired chromatids) 19 20 2. Metaphase Centriole (A) The chromosomes line up across the center/equator of the cell. (B) Spindle microtubules connect the centromere of each chromosome to the centrioles Spindle 21  3. Anaphase (A) The chromatids separate into individual chromosomes. (B) The chromosomes continue to move until they have separated into two groups 22 23  (A) Spindles dissolves 4. Telophase (B) Nuclear forms at each pole (C) Chromosomes uncoil (D) Cytokinesis begins 24  Cytokinesis, During cytokinesis, the cytoplasm is divided in half, and the cell membrane grows to enclose each cell, forming two separate cells. The end result of mitosis and cytokinesis is two genetically identical cells where only one cell existed before. 25 During cytokinesis in animal cells and other cells that lack cell walls, the cell is pinched in half by Pro protein threads. The furrow deepens until the cell is pinched in two 26  cell plate. In plant cells, vesicles formed by the Golgi apparatus fuse at the midline and form a 27 Plant cell mitosis Cell plate Cell wall 28 29 30  Two types of regulatory proteins are involved in cell cycle control: cyclins and Protein kinases The activity of regulatory proteins fluctuates during the cell cycle Most of the kinases are present at a constant concentration but in an inactive form To activate protein kinases they must be attached to cyclins A protein that fluctuate concentration levels in the cell 31 32 Because of this requirement of them having to be activated by a cyclin these protein kinases are called cyclin-dependent kinases (Cdks) Protein kinases The combination of Cyclin and Cdks together is now called MPF (maturation-promoting factor) triggers a cell’s to go past the G2 checkpoint into the M phase The MPF triggers proteins on the nuclear membrane promoting the nucleus membrane to fragment Synthesis of cyclin begins in late S phase and continues through G2 Cyclins regulate the timing of the cell cycle in eukaryotic cells 34  Besides Cyclin there are other proteins that regulate cell activity There are two types of regulating proteins: 1. Internal Regulators 2. External Regulators Example: proteins will prevent cell division Chemical factors until all chromosomes are replicated. Another protein prevents a cell from entering Physical factors anaphase until all chromosomes are attached 35  2. External Regulators Chemical factors Cells fail to divide if an essential nutrient is lacking The most important one is... Growth Factor Certain cells release growth factor protein stimulates other cells to divide. 36  2. External Regulators Physical factors Density-Dependent Inhibition Cells stop dividing when they come into contact with one another. Anchorage dependent To divide cell must be attached to tissue 37  Cancer, claims 1:4 people in the U.S. Cancer is a disease of the cell cycle. Cancer cells do not respond normally to the cell cycle controls. As a result, they divide uncontrollably and form masses of cells called.. Neoplasm/tumor Cancer is rated from stage 1 to stage 4 38 Several cancer cells have a defect in a gene called... p53, which normally stops the cell cycle Damaged or defective p53 cause the cells to lose the information needed to respond to signals that control cell growth. 39 Bio logy C hp. 10 Finish Line 40