Cell Growth and Division Chapter 10
10-1 Cell Growth • Limits to cell growth • The bigger a cell is, the more demands the cell places on its DNA. • The cell has trouble moving enough nutrients and wastes across the cell membrane
10-1 Cell Growth • DNA “overload” • DNA – provides information that controls the cell’s funtions • Small cells have less need for that information than big cells • Big cells may need so much information that the single copy of DNA cannot provide it to all areas of the cell
10-1 Cell Growth • Exchanging materials • Surface area of a cell determines the amount of material exchanged • Oxygen, water, and food • Total area of the cell membrane • Volume of a cell determines how fast these materials are produced (waste) or used (food and oxygen)
10-1 Cell Growth • Ratio of surface area to volume • Surface area / volume • Surface area • Length X Width X Number of sides • units 2 • Volume • Length X Width X Height • units 3
10-1 Cell Growth • If the length of the cell doubles what happens to the ______? • Volume • Surface Area • Ratio SA / V • What does this do to the cell?
10-1 Cell Growth • Division of the cell • Cell division • The process by which a cell divides forming two new daughter cells • This occurs when the cell becomes too big • Before a cell divides, it replicates its DNA.
10-2 Cell Division • What do we call the chromosomes when they have replicated? • What is the structure that holds the replicated chromosomes together? • What is the longest phase of the cell cycle? • In what phase of the cell cycle does the cell do most of their growing? • What does the “S” stand for in the S-phase and what occurs during this phase?
10-2 Cell Division • Chromosomes • Carries the cells genetic information from one generation to the next. • Made of DNA and proteins • Each cell contains a specific number of chromosomes • Humans – 46 • Apes - 48 • Flies - 8 • Carrot – 18 • Dog - 78
10-2 Cell Division • Chromatids • One of two identical “sister” parts of a duplicated chromosome • Centromeres • Area where the chromatids of a chromosome are attached
10-2 Cell Division • The cell cycle • Interphase • Period of the cell cycle between cell divisions • Cell cycle • 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
10-2 Cell Division • Events of the cell cycle • G1 phase • Cell growth • S phase • DNA replication • G2 phase • Preparation for mitosis • M phase • Cell division (mitosis and cytokinesis)
10-2 Cell Division • Mitosis • Division of the cell nucleus • Four phases (PMAT) • Prophase, metaphase, anaphase, and telophase
10-2 Cell Division • Prophase • 1st phase • Longest phase • Chromosomes become visible • Nuclear envelope dissolves • Centrioles separate • Spindles begin to form
10-2 Cell Division • Metaphase • Chromosomes line up across the center of the cell • Each chromosome is connected to a spindle fiber
10-2 Cell Division • Anaphase • Sister chromatids separate into individual chromosomes • Chromosomes move toward opposite poles
10-2 Cell Division • Telophase • Chromosomes gather at the poles and lose their shape • New nuclear envelopes surround each set of chromosomes
10-2 Cell Division • Cytokinesis • Division of the cytoplasm • Each daughter cell has an identical set of chromosomes
10-3 Regulating the Cell Cycle • What are some of the controls of cell division? • What are the substances that regulate the timing of the cell cycle? • What is it called when a cell experiences uncontrolled cell growth? • What are some causes of uncontrolled cell growth? • What is the importance of the p53 gene?
10-3 Regulating the Cell Cycle • Controls of cell division • Cell growth can be turned on or off • On • Injury • Off • Cells become crowded
10-3 Regulating the Cell Cycle • Cell cycle regulators • Something that tells the cell when it is time to divide, duplicate their chromosomes, or enter another phase • Cyclin • Protein that cause spindles to form • Regulate the timing of the cell cycle in eukaryotic cells
10-3 Regulating the Cell Cycle • Internal regulators • Proteins that respond to events inside the cell • Allow the cell to proceed only when certain processes have happened
10-3 Regulating the Cell Cycle • External regulators • Proteins that respond to events outside the cell • Direct the cell to speed up or slow down the cell cycle • Ex. Growth factor
10-3 Regulating the Cell Cycle • Uncontrolled cell growth • Cancer • Cancer cells do not respond to the signals that regulate the growth of most cells