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

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 – Cell specialization; when a cell becomes a certain type of cell with special characteristics. As a result of differentiation, cells vary in size and shape due to their unique function. All cells have a complete set of chromosomes, (except red blood cells, which extrude their nucleus). Cells specialize by expressing only certain genes.

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4. 4 3.2: A Composite Cell Also called a ‘typical’ cell Major parts include: Nucleus Cytoplasm Cell membrane 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

5. 5 Cell Membrane (aka Plasma Membrane) Outer limit of the cell Selectively permeable – controls what enters and leaves the cell Structure - Phospholipid bilayer: Water-soluble “heads” form surfaces (hydrophilic) Water-insoluble “tails” form interior (hydrophobic) Permeable to lipid-soluble substances Cholesterol - strengthens the membrane to help prevent rupture Proteins

6. 6 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.

7. 7 Cell Membrane (aka Plasma Membrane) Proteins – Four main functions in cell membrane: 1) Transport proteins – form pores, channels and carriers for movement of ions and molecules across the cell membrane 2) Receptor proteins - receive and transmit messages for the cell 3) Enzymes – catalyze chemical reactions 4) CAMS (Cell Adhesion Molecules) – enable cells to touch and bind to other cells

8. 8 Cell Adhesion Molecules (CAMs) CAMs help cells to distinguish between “self” and other types of cells. Why is this important? 1) Embryonic development, when cells are aggregating to form tissues and organs. 2) Growth and healing 3) Guides cells that move throughout the body, such as immune cells, so that they can recognize “self” versus “foreign” cells

9. 9 CAMs & The Immune System Clotting blood, dying tissue and bacteria release chemoattractants that attract WBCs to a site of infection in the body : Selectin (on WBC) – allows white blood cells to attach to carbohydrates within a vessel wall near a site of inflammation, and it slows to a roll. Integrin (on WBC) – adheres to receptor proteins in the vessel wall and guides WBC through capillary walls to the site of infection Once the WBC reaches the infection site, it uses CAMs to distinguish between “self” and foreign cell surfaces, such as bacteria, and attacks and kills the foreign cells. Adhesion White blood cell Integrin Selectin Exit Splinter Attachment (rolling) Blood vessel lining cell Carbohydrates on capillary wall Adhesion receptor proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

10. 10 Cytoplasm The contents of a cell, consisting of the cellular organelles, (except the nucleus and cell membrane), suspended in a liquid called the cytosol. The cytoplasm surrounds the nucleus and is contained within the cell membrane.

11. 11 Organelles Endoplasmic Reticulum (ER): composed of interconnected membrane-bound sacs, canals, and vesicles. Provides for a transport system throughout the cell. Rough ER – has ribosomes Protein synthesis Smooth ER Lipid synthesis – lipids added to proteins arriving from rough ER Break down of drugs Ribosomes – tiny spheres composed of rRNA and protein: Free floating or connected to ER Provide the structure and the enzymes needed to link amino acids to form protein Membranes Ribosomes Membranes (b)(c) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

12. 12 Organelles Golgi apparatus – “Post office”: 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. Mitochondrion: Membranous sacs with inner partitions – highly folded membrane forms cristae Generate energy in the form of ATP

13. 13 Organelles Lysosomes “Garbage disposal” digestive enzymes for digesting worn out cell parts and other cellular debris Peroxisomes over 40 different enzymes for catalyzing reactions Enzyme catalase – breaks down hydrogen peroxide (toxic to cell) Centrosome Two rod-like centrioles Used to produce cilia and flagella Forms mitotic spindle to distributes chromosomes during mitosis (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

14. 14 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

15. 15 Microfilaments and microtubules = Cytoskeleton Thin rods and tubules Support cytoplasm Allows for movement of organelles Organelles Inclusions Temporary nutrients and pigments Microtubules Microfilaments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © M. Schliwa/Visuals Unlimited

16. 16 Nucleus 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 (loosely coiled chromo- somes) strands of DNA and proteins called histones. Stores information in the form of genes for synthesis of proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleus Nucleolus Chromatin Nuclear pores Nuclear envelope

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18. 18 3.3: Movements Into and Out of the Cell Passive (Physical) Transport Require no cellular energy (go with, or down, the concentration gradient) Include: Simple diffusion Osmosis Facilitated diffusion Filtration Active (Physiological) Transport Require cellular energy (go up, or against, the concentration gradient) Include: Carrier proteins Endocytosis Exocytosis Transcytosis

19. 19 PASSIVE TRANSPORT 1. Simple Diffusion Movement of substances from regions of higher concentration to regions of lower concentration Lipid-soluble substances freely diffuse through the cell membrane. Examples: Oxygen, carbon dioxide, steroids, and general anesthestics Time Solute molecule Water molecule ABAB (2)(3) Permeable membrane AB (1)

20. 20 Animation: How 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.

21. 21 PASSIVE TRANSPORT 2. Osmosis Diffusion of water through a selectively permeable membrane from regions of higher concentration to regions of lower concentration of water molecules 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.

22. 22 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.

23. 23 PASSIVE TRANSPORT 3. Facilitated Diffusion Diffusion across a membrane with the help of a channel or carrier protein. Which molecules need help? a) Substances that are not lipid- soluble: -Water – through channels called Pores (Aquaporins) -Ions – such as Na+, K+, Cl- b) Larger molecules – such as Glucose and amino acids Region of higher concentration Transported substance Region of lower concentration Protein carrier molecule Cell membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24. 24 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.

25. 25 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 solution – same osmotic pressure as inside a cell Hypertonic solution – higher osmotic pressure than inside a cell (water loss from cell) Hypotonic solution – lower osmotic pressure than inside a cell (water gain in cell) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © David M. Phillips/Visuals Unlimited (b) (a) (c)

26. 26 Blood pressure within blood vessels forces smaller molecules through the thin, porous membranes that line the walls of capillaries, while larger molecules remain in the blood. This causes fluid to accumulate in body tissue. Edema is the accumulation of too much fluid in body tissue. PASSIVE TRANSPORT 4. Filtration

27. 27 Active Transport 1. Carrier Proteins Carrier proteins, (often called “pumps”) move particles across the cell membrane from a region of lower concentration to higher concentration (ie. movement against the concentration gradient) Requires energy in the form of ATP Sugars, amino acids, sodium ions, potassium ions, etc. Almost half of a cell’s energy supply may be used for active transport

28. 28 Animation: How the Sodium-Potassium Pump 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.

29. 29 ACTIVE TRANSPORT 2. Endocytosis Cell engulfs a substance by forming a vesicle around the substance Three types: 1)Pinocytosis – substance is mostly water 2)Phagocytosis – substance is a solid 3)Receptor-mediated endocytosis – requires the substance to bind to a membrane-bound receptor NucleusNucleolus Vesicle Cell membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30. 30 ACTIVE TRANSPORT 2. 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.

31. 31 ACTIVE TRANSPORT 3. Exocytosis Reverse of endocytosis Vesicle within the cell fuses with cell membrane and the contents within the vesicle are released outside the cell. Ex: Release of neurotransmitters from nerve cells Nucleus Endoplasmic reticulum Golgi apparatus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32. 32 ACTIVE TRANSPORT 4. 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

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34. 34 The Cell Cycle Series of changes a cell undergoes from the time it forms until the time it divides. Stages: Interphase Mitosis Cytokinesis

35. 35 1. Interphase Very active period: 1) Cell grows 2) Maintains routine functions 3) Replicates DNA to prepare for nuclear division 4)Synthesizes new organelles to prepare for cytoplasmic division Phases: G1 & G2 phases – cell grows and synthesizes structures other than DNA S phase – cell replicates DNA

36. 36 2. Mitosis Produces two daughter cells from an original somatic cell Karyokinesis – nucleus divides. Four Phases of nuclear division: 1) Prophase – chromosomes form; nuclear envelope disappears 2) Metaphase – chromosomes align midway between centrioles 3) Anaphase – chromosomes separate and move to centrioles 4) Telophase – chromatin forms; nuclear envelope forms

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38. 38 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.

39. 39 3. Cytoplasmic Division Also known as cytokinesis. Begins during anaphase Continues through telophase Contractile ring pinches cytoplasm in half

40. Control of Cell Division Many factors influence how often a cell divides: 1)Cell type – skin and blood cells multiply frequently; cells that give rise to neurons divide a few times, then stop 2)Cell size – once a cell grows to a certain size, it divides to maintain an optimum surface area/volume ratio 3)Telomeres – “mitotic clock” – repeating nucleotide sequences on the tips of chromosomes; each mitosis removes about 1,200 of these nucleotides. Once these tips are ‘worn down’ to a certain point, the cell no longer divides.. 40

41. Control of Cell Division (cont’d) 4) Kinases and cyclins – proteins within the cell that control division 5) Hormones and growth factors – molecules produced at another site in the body 6)Contact inhibition (density-dependent inhibition) – healthy cells do not divide when they are surrounded by other cells. 41

42. Tumors Tumor – a disorganized mass of cells formed when a cell divides out of control. Two types: 1) Benign – remains in one place as a lump. Can eventually interfere with the function of surrounding healthy tissue. 2) Malignant = Cancer (Latin for “the crab”). Invasive tumor that extends into surrounding tissue (resembles a crab with outreaching claws). If not stopped, it can eventually reach the circulation and spread, (metastasize), to other sites in the body. 42

43. 43 Tumors Two major types of genes can 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.;

44. 44 Stem and Progenitor Cells Stem cell – undifferentiated cell that can divide to form two new stem cells (self-renewal) or a stem cell and a progenitor cell. Progenitor cell – “committed” cell. Daughter cell of a stem cell that is partially specialized (can become any of a restricted number of cell types) Totipotent – describes a stem cell that can give rise to every cell type Pluripotent – describes a stem cell or progenitor cell that can give rise to a restricted number of cell types

45. 45 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.

46. 46 Cell Death Apoptosis: Programmed cell death that is a part of normal development and growth in an organism Acts as a protective mechanism A stepwise process that begins when a “death receptor” on the cell’s membrane receives a signal to die. Within seconds, enzymes called caspases are activated inside the cell, where they proceed to cut up various cellular components. Phagocytes move in and break down the debris. Process takes about one hour.

47. Cell Death Necrosis – (Gk. Nekros – dead body) The unprogrammed death of cells or tissues. A disordered form of cell death associated with inflammation and injury that leads to ischemia (lack of blood flow to the affected area, which restricts oxygen and glucose supply to the cells). 47

48. 48 Important Points in Chapter 3: Outcomes to be Assessed 3.1: Introduction Define cell. State the term for cell specialization. 3.2: A Composite Cell List the three major parts of a composite cell. Explain how the structure of a cell membrane makes possible its function. Describe each type of organelle, and explain its function. Describe the parts of a cell nucleus and their functions.

49. 49 Important Points in Chapter 3: Outcomes to be Assessed 3.3: Movement Into and Out of the Cell Explain the various ways that substances move through the cell membrane. 3.4: The Cell Cycle Describe the parts of the cell cycle and identify the major activities during each part. Explain why regulation of the cell cycle is important to health. Distinguish between mitosis and cytokinesis. List the stages of mitosis and describe the events of each stage.

50. 50 Important Points in Chapter 3: Outcomes to be Assessed 3.5: Control of Cell Division Explain how different types of cells differ in their rate of cells division. Discuss factors that influence whether or not a cell divides. Explain how cancer arises from too-frequent cell division. Distinguish the two types of genetic control of cancer. 3.6: Stem and Progenitor Cells Define differentiation. Distinguish between a stem cell and a progenitor cell. Explain how two differentiated cell types can have the same genetic information, but different appearances and functions.

51. 51 Important Points in Chapter 3: Outcomes to be Assessed 3.7: Cell Death Define apoptosis. Distinguish apoptosis from necrosis. Describe the relationship between apoptosis and mitosis.