* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 10 Roche Bio
Survey
Document related concepts
Tissue engineering wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Signal transduction wikipedia , lookup
Spindle checkpoint wikipedia , lookup
Cell membrane wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cell nucleus wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cellular differentiation wikipedia , lookup
Programmed cell death wikipedia , lookup
Endomembrane system wikipedia , lookup
Cell culture wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Cell growth wikipedia , lookup
List of types of proteins wikipedia , lookup
Transcript
Chapter 10 Cell Growth and Division Cell division and mitosis http://www.emc.maricopa.edu/faculty/farabee/biobk/b iobookmito.html 10-1 Why Cell Size do organisms have millions of cells instead of just a few? Why are there limits to how big a cell can become? Cell Size Cells use food, oxygen and water and produce wastes from these processes ◦ The rate depends on the cell’s volume – the amount inside the cell membrane Cells move food, oxygen, water and wastes in and out through the cell membrane. ◦ The rate depends on the cell’s surface area – the measurement of the outside surface of the cell – the cell membrane Limits to Cell Growth The larger a cell becomes, ◦ The more demands it places on its DNA ◦ It becomes more difficult to move enough nutrients and wastes across the cell membrane ◦ If there is more space between the cell’s membrane and the center of the cell, it takes longer to move materials in and out Ratio of Surface Area to Volume As the length of the cell increases, the volume increases faster than the surface area! The RATIO of surface area to volume decreases! *** This number needs to be large! **** Now it is too difficult for cell to move needed materials in & waste products out quickly enough. At this point the growing cell divides into two smaller “daughter” cells. Copyright Pearson Prentice Hall 10-2 In Cell Division eukaryotic cells, cell division occurs in two major stages: 1. mitosis: division of the cell nucleus 2. cytokinesis: division of the cell cytoplasm Chromosomes: carry genetic information ◦ Before cell division, each chromosome is duplicated, or copied. Chromosomes copyright cmassengale 9 Chromosomes ◦ Each chromosome consists of two identical “sister” chromatids. ◦ Each pair of chromatids is attached at an area called the centromere. ◦ When the cell divides, the chromatids separate. ◦ Each new cell gets one chromatid. Sister chromatids Centromere Copyright Pearson Prentice Hall The Cell Cycle A series of events that cells go through as they grow and divide Interphase is a period of growth that occurs between cell divisions The Cell Cycle has four phases 1. ◦ ◦ 2. ◦ ◦ 3. ◦ 4. ◦ ◦ G1 = First Gap Phase = growth phase Cell increases in size Cell synthesizes new proteins and organelles S Phase = synthesis phase Chromosomes replication DNA synthesis G2 = Second Gap Phase Organelles and molecules needed for cell division (mitosis) are produced M Phase = Mitosis Mitosis has four phases: prohase, metaphase, anaphase and telophase. Followed by cytokenisis. Events of the Cell Cycle Copyright Pearson Prentice Hall Phases of Cell Division Prophase ◦ Centrioles and spindle forms ◦ Nuclear envelope breaks down ◦ Chromosomes become visible Metaphase ◦ Chromosomes line up in the middle of the cell ◦ Spindle connects to centromeres Anaphase ◦ Chromosome pairs are separated Telophase ◦ Chromosomes gather at either end ◦ Nuclear envelope re-forms Cytokinesis ◦ Cytoplasm pinches ◦ Two daughter cells are made Mitosis = Division of Nucleus 10-2 Cell Division Mitosis Prophase Spindle forming Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. The spindle is a fanlike microtubule structure that helps separate the chromosomes. Centromere Copyright Pearson Prentice Hall Chromosomes (paired chromatids) Slide 18 of 38 10-2 Cell Division Mitosis Spindle forming Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Centromere Chromosomes (paired chromatids) Slide 19 of 38 Copyright Pearson Prentice Hall 10-2 Cell Division Mitosis Centriole Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Spindle Slide 20 of 38 Copyright Pearson Prentice Hall 10-2 Cell Division Mitosis Anaphase Individual chromosomes Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Slide 21 of 38 Copyright Pearson Prentice Hall 10-2 Cell Division Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape. A new nuclear envelope forms around each cluster of chromosomes. Copyright Pearson Prentice Hall Slide 22 of 38 10-2 Cell Division Cytokinesis Cytokinesis During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes. Slide 23 of 38 Copyright Pearson Prentice Hall 10-2 Cell Division Cytokinesis In plants, a cell plate forms midway between the divided nuclei, developing into a separating membrane. A cell wall then appears in the cell plate. Cell plate Cell wall Slide 24 of 38 Copyright Pearson Prentice Hall 10-3 Controls on Cell Division Experiments have shown that normal cells will reproduce until they come into contact with other cells. They respond by not growing. This demonstrates that controls on cell growth and division can be turned on and off. 10-3 Regulating the Cell Cycle Controls on Cell Division Contact Inhibition Slide 26 of 18 Copyright Pearson Prentice Hall Cell Cycle Regulators - CYCLINS Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells. The amount of cyclin in cells rises and falls in time with the cell cycle 10-3 Regulating the Cell Cycle Cell Cycle Regulators Cyclins were discovered during a similar experiment to this one. A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G2 of interphase. As a result, the second cell enters mitosis. Slide 28 of 18 Copyright Pearson Prentice Hall 10-3 Regulating the Cell Cycle Cell Cycle Regulators Cyclins were discovered during a similar experiment to this one. A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G2 of interphase. As a result, the second cell enters mitosis. Slide 29 of 18 Copyright Pearson Prentice Hall Internal and External Cell Regulators Internal: ◦ Proteins that respond to events inside the cell ◦ Allow cell cycle to proceed only when certain processes have occurred inside the cell External: ◦ Proteins that respond to events outside the cell ◦ Direct cells to speed up or slow down the cell cycle Uncontrolled Cell Growth - Cancer A disorder in which some of the body’s cells lose the ability to control growth Cancer cells don’t respond to the signals that regulate growth Cancer cells divide uncontrollably forming masses of cells called tumors; ◦ Tumors can damage surrounding tissues ◦ Cancer cells can break loose from tumors and spread throughout the body