Cells Chapter 4 Copyright Mc GrawHill Companies Permission

Cells Chapter 4 Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Outline • • • Cell Theory Plasma Membrane Prokaryotic Cells Eukaryotic Cells Cytoskeleton Cell Organelles Cell Movement Diffusion and Osmosis Bulk Passage Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cell Theory • • Robert Hooke (1665) v Observed thin slice of nonliving plant tissue. - Observed honeycombed compartments he called cellulae (small rooms). Matthias Schleiden (1838) first statement of cell theory. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cell Theory • • All organelles are composed of one or more cells, within which life processes occur. Cells are smallest living things. Life evolved only once, 3. 5 billion years ago. Cells arise only by division of a previously existing cell. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cell Size • Cells range in size from 5 -20 micrometers to 5 cm long. v Most cells are small because larger cells do not function as efficiently. v As cell size increases, volume increases more rapidly than surface area. - Larger cells have less surface area per unit volume, thus less opportunity to interact with the environment. - Cytoplasm fills cell interior. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Plasma Membrane • Cell membrane made up of diverse collection of proteins floating within lipid framework. v Fluid Mosaic Model - Lipid bilayer forms when phospholipids are placed in water. Ø Hydrophobic tails pointing in, hydrophilic heads pointing outward. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Lipid Bilayer Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Plasma Membrane • Membrane Proteins - Float freely within lipid bilayer. v Cell Surface Proteins - Act as markers to identify particular types of cells. v Transmembrane Proteins - Span entire membrane. Provide channels for molecule passage. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Lipid Bilyer Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Prokaryotic Cells • Prokaryotes have a relatively uniform cytoplasm not subdivided by interior membranes (No interior compartments). v Bacteria are simplest cellular organisms. - Over 2, 500 recognized species. - Almost all are contained by a cell wall. Ø Some bacteria contain another layer (capsule) enclosing the cell. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Prokaryotic Cells Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Eukaryotic Cells • Contain many membrane-bound interior compartments and a variety of organelles. v Specialized structures performing specific processes. - Nucleus Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cytoskeleton • Cytoskeleton - dense network of protein fibers supporting cell shape. v Microfilaments v Microtubules v Intermediate Fibers Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cell Organelles • Eukaryotic cells thought to have evolved from endosymbiosis between different species of prokaryotes. v Engulfed prokaryotes provided hosts with certain metabolic advantages. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Nucleus • • Nucleus - Command control center. v Bound by nuclear envelope. - Covered with nuclear pores embedded by proteins permitting proteins and RNA to pass in and out of nucleus. v Contain chromosomes holding DNA. Nucleolus - Cluster of genes encoding r. RNA. v Ribosome reads RNA and directs protein building. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Nucleus Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Endomembrane System • Endoplasmic Reticulum v Internal membrane creating channels and membrane-enclosed vesicles. - Carbohydrates and lipids manufactured on the surface. - Proteins for export produced on surface covered with ribosomes (Rough ER). Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Endomembrane System • • • Golgi Complex v Golgi bodies are scattered throughout the cytoplasm. Function in collection, packaging, and distribution of molecules manufactured in the cell. Lysosomes v Arise from Golgi complex and break down macromolecules. (Recycling center) Peroxisomes - Vesicles carrying out specific chemical functions. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Endomembrane System Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

DNA Containing Organelles • Mitochondria v Double membrane organelles that extract energy from organic molecules. - (Oxidative Metabolism) v Inner membrane bent into numerous folds (cristae) that partitions mitochondrion into inner matrix and outer compartment. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Mitochondria Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

DNA Containing Organelles • Chloroplasts v Double membrane organelles that serve as site of photosynthesis. v Inner membranes fused to form stacks of thylakoids, which are stacked on top of one another to form a column (granum). - Interior bathed with semiliquid (stroma). Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Chloroplasts Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Cell Movement • • Microvilli project outward form surface of animal cells. Arrangement of actin filaments within cell cytoplasm allow cells to crawl. Flagella are fine, threadlike organelles protruding from cell surface. v Arise from basal body and consist of nine microtubule pairs surrounding two central pairs. Cilia - Short, numerous flagella. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Flagella and Cilia Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Plant Cells Are Unique • • Central Vacuole - Large storage center for certain cell substances, and increases surface to volume ratio. Cell Walls - Composed of cellulose fibers. v Primary Walls v Middle Lamella v Secondary Walls Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Diffusion and Osmosis • Diffusion v Random motion of molecules produces uniform mixture due to net movement of molecules down a concentration gradient (high concentration to low concentration). Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Diffusion and Osmosis • Osmosis v Diffusion of water across a membrane toward the side with polar molecules that cannot traverse the membrane. Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Diffusion and Osmosis • Solute - Substance dissolved in a solution. v Hyperosmotic - Solution with higher concentration of solutes. v Hypoosmotic - Solution with lower concentration of solutes. v Isomotic - Osmotic concentration of both solution are equal. v Osmotic Pressure - Pressure caused by movement of water into a cell. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Bulk Passage • • Endocytosis - Cell membrane engulfs particle and forms a vesicle, bringing the particle into the interior of the cell. Excoytosis - Reverse of endocytosis. Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Selective Permeability • Protein channels in membrane only allow passage of certain kinds of molecules. v Selective Diffusion allows molecules to move through channels and equalize concentrations. v Facilitated Diffusion - net movement down a concentration gradient facilitated by carrier proteins. Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Facilitated Diffusion Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Active Transport • Active Transport - Using energy to move molecules through membrane protein channels against a concentration gradient. v Sodium-Potassium Pump v Proton Pump Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Active Transport Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

How Cells Get Information • • Chemical information sensed by surface receptor proteins. v Hormone signals Voltage sensed by specialized ion channels. Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Review • • • Cell Theory Plasma Membrane Prokaryotic Cells Eukaryotic Cells Cytoskeleton Cell Organelles Cell Movement Diffusion and Osmosis Bulk Passage Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies

Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3 rd Ed. - All Rights Reserved - Mc. Graw Hill Companies