1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Lecture PowerPoint Cells

2. 2 3.1: Introduction The basic organizational structure of the human body is the cell. There are 50-100 trillion cells in the human body. Differentiation is when cells specialize. As a result of differentiation, cells vary in size and shape due to their unique function.

3. 3 3.2: A Composite Cell Major parts include: Nucleus contains DNA Cytoplasm cellular contents between plasma membrane & nucleus Cell membrane selective barrier Microtubules Flagellum Nuclear envelope Basal body Chromatin Ribosomes Cell membrane Mitochondrion Cilia Microtubules Microtubule Centrioles Microvilli Lysosomes Nucleolus Nucleus Phospholipid bilayer Smooth Endoplasmic reticulum Rough Endoplasmic reticulum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Golgi apparatus Secretory vesicles

4. Cell Membrane (aka Plasma Membrane) Outer limit of the cell Controls what moves in and out of the cell Selectively permeable Phospholipid bilayer Water-soluble “heads” form surfaces (hydrophilic) Water-insoluble “tails” form interior (hydrophobic) Permeable to lipid-soluble substances Cholesterol stabilizes the membrane 4

5. 5 Cell Membrane Cell membrane (b) (a) “Heads” of phospholipid “Tails” of phospholipid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Biophoto Associates/Photo Researchers, Inc. Fibrous protein CarbohydrateGlycolipid Glycoprotein Extracellular side of membrane Cytoplasmic side of membrane Cholesterol molecules Globular protein Double layer of Phospholipid molecules Hydrophobic fatty acid “tail” Hydrophilic Phosphate “head” Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

6. 6 Cytoplasm Cytosol = water Organelles = solids Cytoplasm is really like a Jello fruit salad where the Jello is the cytosol and the fruits (oranges, grapes, bananas, maybe walnuts, etc.) are the organelles.

7. 7 Organelles Endoplasmic Reticulum (ER) Connected, membrane-bound sacs, canals, and vesicles Transport system Rough ER Studded with ribosomes Smooth ER Lipid synthesis Added to proteins arriving from rough ER Break down of drugs Ribosomes Free floating or connected to ER Provide structural support and enzyme activity to amino acids to form protein (protein synthesis) Membranes Ribosomes Membranes (b)(c) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8. 8 Organelles Golgi apparatus Stack of flattened, membranous sacs Modifies, packages and delivers proteins Vesicles Membranous sacs Store substances Inner membrane Outer membrane Cristae (a)(b) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Bill Longcore/Photo Researchers, Inc. Mitochondria Membranous sacs with inner partitions Generate energy

9. 9 Organelles Lysosomes Enzyme-containing sacs Digest worn out cell parts or unwanted substances Peroxisomes Enzyme-containing sacs Break down organic molecules Detoxifies alcohol Centrosome Two rod-like centrioles Used to produce cilia and flagella Distributes chromosomes during cell division (a)(b) Centriole (cross-section) Centriole (longitudinal section) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Don W. Fawcett/Visuals Unlimited

10. 10 Organelles Cilia Short hair-like projections Propel substances on cell surface Flagellum Long tail-like projection Provides motility to sperm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Oliver Meckes/Photo Researchers, Inc. © Colin Anderson/Brand X/CORBIS

11. 11 Microfilaments and microtubules Thin rods and tubules Support cytoplasm Allows for movement of organelles Organelles Microtubules Microfilaments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © M. Schliwa/Visuals Unlimited

12. 12 Cell Nucleus Is the control center of the cell Nuclear envelope Porous double membrane Separates nucleoplasm from cytoplasm Nucleolus Dense collection of RNA and proteins Site of ribosome production Chromatin Fibers of DNA and proteins Stores information for synthesis of proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleus Nucleolus Chromatin (a) Nuclear pores Nuclear envelope

13. 3.3: Movements Into and Out of the Cell There are 2 ways substances move through the cell membrane. 13 Passive mechanisms do not require energy. Simple diffusion Facilitated diffusion Osmosis Filtration Active mechanisms require cell energy Active transport Endocytosis Exocytosis Transcytosis

14. 14 Simple Diffusion The process by which molecules or ions scatter or spread spontaneously from a higher concentration to a lower concentration Oxygen and carbon dioxide can diffuse readily through the cell membrane Equilibrium is reached. Time Solute molecule Water molecule ABAB (2)(3) Permeable membrane AB (1)

15. Animation: How Diffusion Works 15

16. 16 Facilitated Diffusion Substances that are not able to pass through the lipid bilayer need the help of membrane proteins to get across, this is called Facilitated Diffusion Carrier molecules “revolving doors” are used to carry large molecules (transported substance) across the membrane. Ex. Glucose and amino acids Region of higher concentration Transported substance Region of lower concentration Protein carrier molecule Cell membrane

17. 17 Animation: How Facilitated Diffusion Works Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

18. 18 Osmosis The diffusion of water Water moves toward a higher concentration of solutes Time Protein molecule Water molecule A B AB (1)(2) Selectively permeable membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

19. 19 Animation: How Osmosis Works Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

20. 20 Osmosis and Osmotic Pressure Osmotic Pressure – ability of osmosis to generate enough pressure to move a volume of water Osmotic pressure increases as the concentration of nonpermeable solutes increases Isotonic – same osmotic pressure Hypertonic – higher osmotic pressure (water loss) Hypotonic – lower osmotic pressure (water gain) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © David M. Phillips/Visuals Unlimited (b) (a) (c)

21. 21 Filtration Smaller molecules are forced through porous membranes Hydrostatic pressure important in the body Molecules leaving blood capillaries Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Capillary wall Larger molecules Smaller molecules Blood pressure Blood flow Tissue fluid

22. 22 Active Transport The process that moves particles through membranes from regions of lower concentration to regions of higher concentration Equilibrium is never reached. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carrier proteinBinding site (a) (b) Cell membrane Carrier protein with altered shape Phospholipid molecules Transported particle Cellular energy Region of higher concentration Region of lower concentration

23. 23 Active Transport: Sodium-Potassium Pump Active transport mechanism Creates balance by “pumping” three (3) sodium (Na+) OUT and two (2) potassium (K+) INTO the cell 3:2 ratio

24. 24

25. 25 Endocytosis Cell engulfs a substance by forming a vesicle around the substance Three types: Pinocytosis – substance is mostly water Phagocytosis – substance is a solid Receptor-mediated endocytosis – requires the substance to bind to a membrane-bound receptor NucleusNucleolus ParticleVesicle Phagocytized particle Cell membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

26. 26 Endocytosis Cytoplasm Vesicle (a)(b)(c)(d) Receptor protein Cell membrane Molecules outside cell Cell membrane indenting Receptor-ligand combination NucleusNucleolus Particle Vesicle Phagocytized particle Cell membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

27. 27 Exocytosis Reverse of endocytosis Substances in a vesicle fuse with cell membrane Contents released outside the cell Release of neurotransmitters from nerve cells Nucleus Endoplasmic reticulum Golgi apparatus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28. 28 Transcytosis Endocytosis followed by exocytosis Transports a substance rapidly through a cell HIV crossing a cell layer Viruses bud HIV Exocytosis Receptor-mediated endocytosis HIV-infected white blood cells Anal or vaginal canal Lining of anus or vagina (epithelial cells) Virus infects white blood cells on other side of lining Receptor-mediated endocytosis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cell membrane

29. 29 3.4: The Cell Cycle Series of changes a cell undergoes from the time it forms until the time it divide Stages: Interphase Mitosis Cytokinesis Apoptosis G 2 phase Prophase Metaphase Anaphase Telophase Cytokinesis Restriction checkpoint Remain specialized Proceed to division S phase: genetic material replicates G 1 phase cell growth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30. Interphase 30 Apoptosis G 2 phase Prophase Metaphase Anaphase Telophase Cytokinesis Restriction checkpoint Remain specialized Proceed to division S phase: genetic material replicates G 1 phase cell growth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Very active period 3 Phases are involved During the G 1 phase, the cell grows During the S phase, the cell replicates DNA During the G 2 phase, the cell is in preparation for cell division

31. Mitosis Produces two daughter cells from an original somatic cell Nucleus divides – karyokinesis Cytoplasm divides – cytokinesis Phases of nuclear division: Prophase – chromosomes form; nuclear envelope disappears Metaphase – chromosomes align midway between centrioles Anaphase – chromosomes separate and move to centrioles Telophase – chromatin forms; nuclear envelope forms 31

32. 32 Mitosis Telophase and Cytokinesis Nuclear envelopes begin to reassemble around two daughter nuclei. Chromosomes decondense. Spindle disappears. Division of the cytoplasm into two cells. Anaphase Sister chromatids separate to opposite poles of cell. Events begin which lead to cytokinesis. Metaphase Chromosomes align along equator, or metaphase plate of cell. Prophase Chromosomes condense and become visible. Nuclear envelope and nucleolus disperse. Spindle apparatus forms. Late Interphase Cell has passed the restriction checkpoint and completed DNA replication, as well as replication of centrioles and mitochondria, and synthesis of extra membrane. Early Interphase of daughter cells— a time of normal cell growth and function. Cleavage furrow Nuclear envelopes Nuclear envelope Chromatin fibers Chromosomes Spindle fiber Centromere Aster Centrioles Late prophase Sister chromatids Microtubules Mitosis Cytokinesis S phase G 1 phase Interphase Restriction checkpoint (a) (b) (c)(d) (e) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke G 2 phase

33. 33 Animation: Mitosis and Cytokinesis Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

34. 34 Cytoplasmic Division Also known as cytokinesis Begins during anaphase Continues through telophase Contractile ring pinches cytoplasm in half

35. 35 Animation: Control of the Cell Cycle Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

36. 36 3.5: Control of Cell Division Cell division capacities vary greatly among cell types Skin and blood cells divide often and continually Neuron cells divide a specific number of times then cease Chromosome tips (telomeres) that shorten with each mitosis provide a mitotic clock Cells divide to provide a more favorable surface area to volume relationship Growth factors and hormones stimulate cell division Hormones stimulate mitosis of smooth muscle cells in uterus Epidermal growth factor stimulates growth of new skin Tumors are the consequence of a loss of cell cycle control Contact (density dependent) inhibition

37. 37 Tumors Two types of tumors: Benign – usually remains localized Malignant – invasive and can metastasize; cancerous Two major types of genes cause cancer: Oncogenes – activate other genes that increase cell division Tumor suppressor genes – normally regulate mitosis; if inactivated they are unable to regulate mitosis Cells are now known as “immortal” Normal cells (with hairlike cilia) Cancer cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Tony Brain/Photo Researchers, Inc.;

38. 38 Animation: How Tumor Suppressor Genes Block Cell Division Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

39. 39 3.6: Stem and Progenitor Cells Stem cell: Can divide to form two new stem cells Self-renewal Can divide to form a stem cell and a progenitor cell Totipotent – can give rise to every cell type Pluripotent – can give rise to a restricted number of cell types Progenitor cell: Committed cell Can divide to become any of a restricted number of cells Pluripotent

40. 40 Stem and Progenitor Cells one or more steps Sperm Egg Fertilized egg Stem cell Progenitor cell Progenitor cell Progenitor cell Blood cells and platelets Fibroblasts (a connective tissue cells) Bone cells Progenitor cell Astrocyte Neuron Skin cell Sebaceous gland cell produces another stem cell (self-renewal) Progenitor cell Progenitor cell Progenitor cell Progenitor cell Progenitor cell Progenitor cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

41. 41 3.7: Cell Death Apoptosis: Programmed cell death Acts as a protective mechanism Is a continuous process