Cells and Tissues PDF

Chapter 3 Cells and Tissues Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College...

Chapter 3 Cells and Tissues Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College © 2018 Pearson Education, Ltd.  Part I: Cells ▪ Cells are the structural units of all living things ▪ The human body has 50 to 100 trillion cells © 2018 Pearson Education, Ltd.  Overview of the Cellular Basis of Life ▪ The Cell Theory 1. A cell is the basic structural and functional unit of living organisms 2. The activity of an organism depends on the collective activities of its cells 3. According to the principle of complementarity, the biochemical activities of cells are dictated by their structure (anatomy) which determines their function (physiology) 4. Continuity of life has a cellular basis © 2018 Pearson Education, Ltd.  Overview of the Cellular Basis of Life ▪ Most cells are composed of four elements: 1. Carbon 2. Hydrogen 3. Oxygen 4. Nitrogen ▪ Cells are about 60% water © 2018 Pearson Education, Ltd.  Anatomy of a Generalized Cell ▪ In general, a cell has three main regions or parts: 1. Nucleus 2. Cytoplasm 3. Plasma membrane © 2018 Pearson Education, Ltd. Figure 3.1a Anatomy of the generalized animal cell nucleus. Nucleus Cytoplasm Plasma membrane (a) Generalized animal cell © 2018 Pearson Education, Ltd.  The Nucleus ▪ Control center of the cell ▪ Contains genetic material known as deoxyribonucleic acid, or DNA ▪ DNA is needed for building proteins ▪ DNA is necessary for cell reproduction ▪ Three regions: 1. Nuclear envelope (membrane) 2. Nucleolus 3. Chromatin © 2018 Pearson Education, Ltd. Figure 3.1b Anatomy of the generalized animal cell nucleus. Nuclear envelope Chromatin Nucleus Nucleolus Nuclear pores (b) Nucleus © 2018 Pearson Education, Ltd.  The Nucleus ▪ Nuclear envelope (membrane) ▪ Consists of a double membrane that bounds the nucleus ▪ Contains nuclear pores that allow for exchange of material with the rest of the cell ▪ Encloses the jellylike fluid called the nucleoplasm © 2018 Pearson Education, Ltd.  The Nucleus ▪ Nucleolus ▪ Nucleus contains one or more dark-staining nucleoli ▪ Sites of ribosome assembly ▪ Ribosomes migrate into the cytoplasm through nuclear pores to serve as the site of protein synthesis © 2018 Pearson Education, Ltd.  The Nucleus ▪ Chromatin ▪ Composed of DNA wound around histones (proteins) ▪ Scattered throughout the nucleus and present when the cell is not dividing ▪ Condenses to form dense, rodlike bodies called chromosomes when the cell divides © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Transparent barrier for cell contents ▪ Contains cell contents ▪ Separates cell contents from surrounding environment © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Fluid mosaic model is constructed of: ▪ Two layers of phospholipids arranged “tail to tail” ▪ Cholesterol and proteins scattered among the phospholipids ▪ Sugar groups may be attached to the phospholipids, forming glycolipids © 2018 Pearson Education, Ltd. Figure 3.2 Structure of the plasma membrane. Extracellular fluid Glycoprotein Glycolipid (watery environment) Cholesterol Sugar group Polar heads of phospholipid molecules Bimolecular lipid layer containing proteins Channel Nonpolar tails of Proteins Filaments of phospholipid molecules cytoskeleton Cytoplasm (watery environment) © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Phospholipid arrangement in the plasma membrane ▪ Hydrophilic (“water loving”) polar “heads” are oriented on the inner and outer surfaces of the membrane ▪ Hydrophobic (“water fearing”) nonpolar “tails” form the center (interior) of the membrane ▪ This interior makes the plasma membrane relatively impermeable to most water-soluble molecules © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Role of proteins ▪ Responsible for specialized membrane functions: ▪ Enzymes ▪ Receptors for hormones or other chemical messengers ▪ Transport as channels or carriers © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Role of sugars ▪ Glycoproteins are branched sugars attached to proteins that abut the extracellular space ▪ Glycocalyx is the fuzzy, sticky, sugar-rich area on the cell’s surface © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Cell membrane junctions ▪ Cells are bound together in three ways: 1. Glycoproteins in the glycocalyx act as an adhesive or cellular glue 2. Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion 3. Special cell membrane junctions are formed, which vary structurally depending on their roles © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Main types of cell junctions ▪ Tight junctions ▪ Impermeable junctions ▪ Bind cells together into leakproof sheets ▪ Plasma membranes fuse like a zipper to prevent substances from passing through extracellular space between cells © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Main types of cell junctions (continued) ▪ Desmosomes ▪ Anchoring junctions, like rivets, that prevent cells from being pulled apart as a result of mechanical stress ▪ Created by buttonlike thickenings of adjacent plasma membranes © 2018 Pearson Education, Ltd.  The Plasma Membrane ▪ Main types of cell junctions (continued) ▪ Gap junctions (communicating junctions) ▪ Allow communication between cells ▪ Hollow cylinders of proteins (connexons) span the width of the abutting membranes ▪ Molecules can travel directly from one cell to the next through these channels © 2018 Pearson Education, Ltd. Figure 3.3 Cell junctions. Microvilli Tight (impermeable) junction Desmosome (anchoring junction) Plasma membranes of adjacent cells Connexon Underlying Extracellular Gap basement space between (communicating) membrane cells junction © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ The cellular material outside the nucleus and inside the plasma membrane ▪ Site of most cellular activities ▪ Includes cytosol, inclusions, and organelles © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Three major component of the cytoplasm 1. Cytosol: Fluid that suspends other elements and contains nutrients and electrolytes 2. Inclusions: Chemical substances, such as stored nutrients or cell products, that float in the cytosol 3. Organelles: Metabolic machinery of the cell that perform functions for the cell ▪ Many are membrane-bound, allowing for compartmentalization of their functions © 2018 Pearson Education, Ltd. Figure 3.4 Structure of the generalized cell. Chromatin Nuclear envelope Nucleolus Nucleus Plasma Smooth endoplasmic membrane reticulum Cytosol Lysosome Mitochondrion Rough endoplasmic reticulum Centrioles Ribosomes Golgi apparatus Secretion being released Microtubule from cell by exocytosis Peroxisome Intermediate filaments © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Mitochondria ▪ “Powerhouses” of the cell ▪ Mitochondrial wall consists of a double membrane with cristae on the inner membrane ▪ Carry out reactions in which oxygen is used to break down food into ATP molecules © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Ribosomes ▪ Made of protein and ribosomal RNA ▪ Sites of protein synthesis in the cell ▪ Found at two locations: ▪ Free in the cytoplasm ▪ As part of the rough endoplasmic reticulum © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Endoplasmic reticulum (ER) ▪ Fluid-filled tunnels (or canals) that carry substances within the cell ▪ Continuous with the nuclear membrane ▪ Two types: ▪ Rough ER ▪ Smooth ER © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Endoplasmic reticulum (ER) (continued) ▪ Rough endoplasmic reticulum ▪ Studded with ribosomes ▪ Synthesizes proteins ▪ Transport vesicles move proteins within cell ▪ Abundant in cells that make and export proteins © 2018 Pearson Education, Ltd. Figure 3.5 Synthesis and export of a protein by the rough ER. Slide 1 Ribosome mRNA 1 As the protein is synthesized on the ribosome, Rough ER it migrates into the rough ER tunnel system. 2 1 3 2 In the tunnel, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Protein 3 The protein is packaged in a tiny membranous sac called a transport vesicle. Transport 4 vesicle buds off 4 The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing. Protein inside transport vesicle © 2018 Pearson Education, Ltd. Figure 3.5 Synthesis and export of a protein by the rough ER. Slide 2 Ribosome mRNA 1 As the protein is synthesized on the ribosome, Rough ER it migrates into the rough ER tunnel system. 1 Protein © 2018 Pearson Education, Ltd. Figure 3.5 Synthesis and export of a protein by the rough ER. Slide 3 Ribosome mRNA 1 As the protein is synthesized on the ribosome, Rough ER it migrates into the rough ER tunnel system. 2 1 2 In the tunnel, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Protein © 2018 Pearson Education, Ltd. Figure 3.5 Synthesis and export of a protein by the rough ER. Slide 4 Ribosome mRNA 1 As the protein is synthesized on the ribosome, Rough ER it migrates into the rough ER tunnel system. 2 1 3 2 In the tunnel, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Protein 3 The protein is packaged in a tiny membranous sac called a transport vesicle. Transport vesicle buds off © 2018 Pearson Education, Ltd. Figure 3.5 Synthesis and export of a protein by the rough ER. Slide 5 Ribosome mRNA 1 As the protein is synthesized on the ribosome, Rough ER it migrates into the rough ER tunnel system. 2 1 3 2 In the tunnel, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Protein 3 The protein is packaged in a tiny membranous sac called a transport vesicle. Transport 4 vesicle buds off 4 The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing. Protein inside transport vesicle © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Endoplasmic reticulum (ER) (continued) ▪ Smooth endoplasmic reticulum ▪ Lacks ribosomes ▪ Functions in lipid metabolism ▪ Detoxification of drugs and pesticides © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Golgi apparatus ▪ Appears as a stack of flattened membranes associated with tiny vesicles ▪ Modifies and packages proteins arriving from the rough ER via transport vesicles ▪ Produces different types of packages ▪ Secretory vesicles (pathway 1) ▪ In-house proteins and lipids (pathway 2) ▪ Lysosomes (pathway 3) © 2018 Pearson Education, Ltd. Figure 3.6 Role of the Golgi apparatus in packaging the products of the rough ER. Rough ER Tunnels Proteins in tunnels Membrane Lysosome fuses with ingested substances. Transport vesicle Golgi vesicle containing digestive enzymes becomes a lysosome. Pathway 3 Pathway 2 Golgi vesicle containing Golgi membrane components apparatus fuses with the plasma Secretory vesicles Pathway 1 membrane and is Proteins incorporated into it. Golgi vesicle containing proteins to be secreted becomes a secretory Plasma membrane Secretion by vesicle. exocytosis Extracellular fluid © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Lysosomes ▪ Membranous “bags” that contain digestive enzymes ▪ Enzymes can digest worn-out or nonusable cell structures ▪ House phagocytes that dispose of bacteria and cell debris © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Peroxisomes ▪ Membranous sacs of oxidase enzymes ▪ Detoxify harmful substances such as alcohol and formaldehyde ▪ Break down free radicals (highly reactive chemicals) ▪ Free radicals are converted to hydrogen peroxide and then to water ▪ Replicate by pinching in half or budding from the ER © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Cytoskeleton ▪ Network of protein structures that extend throughout the cytoplasm ▪ Provides the cell with an internal framework that determines cell shape, supports organelles, and provides the machinery for intracellular transport ▪ Three different types of elements form the cytoskeleton: 1. Microfilaments (largest) 2. Intermediate filaments 3. Microtubules (smallest) © 2018 Pearson Education, Ltd. Figure 3.7 Cytoskeletal elements support the cell and help to generate movement. (a) Microfilaments (b) Intermediate filaments (c) Microtubules Tubulin subunits Fibrous subunits Actin subunit 7 nm 10 nm 25 nm Microfilaments form the blue Intermediate filaments form Microtubules appear as gold batlike network. the purple network surrounding networks surrounding the cells’ the pink nucleus. pink nuclei. © 2018 Pearson Education, Ltd.  The Cytoplasm ▪ Centrioles ▪ Rod-shaped bodies made of nine triplets of microtubules ▪ Generate microtubules ▪ Direct the formation of mitotic spindle during cell division © 2018 Pearson Education, Ltd. Table 3.1 Parts of the Cell: Structure and Function (1 of 5) © 2018 Pearson Education, Ltd. Table 3.1 Parts of the Cell: Structure and Function (2 of 5) © 2018 Pearson Education, Ltd. Table 3.1 Parts of the Cell: Structure and Function (3 of 5) © 2018 Pearson Education, Ltd. Table 3.1 Parts of the Cell: Structure and Function (4 of 5) © 2018 Pearson Education, Ltd. Table 3.1 Parts of the Cell: Structure and Function (5 of 5) © 2018 Pearson Education, Ltd.  Cell Extensions ▪ Surface extensions found in some cells ▪ Cilia move materials across the cell surface ▪ Located in the respiratory system to move mucus ▪ Flagella propel the cell ▪ The only flagellated cell in the human body is sperm ▪ Microvilli are tiny, fingerlike extensions of the plasma membrane ▪ Increase surface area for absorption © 2018 Pearson Education, Ltd. Figure 3.8g Cell diversity. Nucleus Flagellum Sperm (g) Cell of reproduction © 2018 Pearson Education, Ltd.  Cell Diversity ▪ The human body houses over 200 different cell types ▪ Cells vary in size, shape, and function ▪ Cells vary in length from 1/12,000 of an inch to over 1 yard (nerve cells) ▪ Cell shape reflects its specialized function © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cells that connect body parts ▪ Fibroblast ▪ Secretes cable-like fibers ▪ Erythrocyte (red blood cell) ▪ Carries oxygen in the bloodstream © 2018 Pearson Education, Ltd. Figure 3.8a Cell diversity. Fibroblasts Rough ER and Golgi apparatus No organelles Secreted fibers Nucleus Erythrocytes (a) Cells that connect body parts © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cells that cover and line body organs ▪ Epithelial cell ▪ Packs together in sheets ▪ Intermediate fibers resist tearing during rubbing or pulling © 2018 Pearson Education, Ltd. Figure 3.8b Cell diversity. Epithelial Nucleus cells Intermediate filaments (b) Cells that cover and line body organs © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cells that move organs and body parts ▪ Skeletal muscle and smooth muscle cells ▪ Contractile filaments allow cells to shorten forcefully © 2018 Pearson Education, Ltd. Figure 3.8c Cell diversity. Skeletal muscle cell Nuclei Contractile Smooth filaments muscle cells (c) Cells that move organs and body parts © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cell that stores nutrients ▪ Fat cells ▪ Lipid droplets stored in cytoplasm © 2018 Pearson Education, Ltd. Figure 3.8d Cell diversity. Fat cell Lipid droplet Nucleus (d) Cell that stores nutrients © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cell that fights disease ▪ White blood cells, such as the macrophage (a phagocytic cell) ▪ Digests infectious microorganisms © 2018 Pearson Education, Ltd. Figure 3.8e Cell diversity. Lysosomes Macrophage Pseudopods (e) Cell that fights disease © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cell that gathers information and controls body functions ▪ Nerve cell (neuron) ▪ Receives and transmits messages to other body structures © 2018 Pearson Education, Ltd. Figure 3.8f Cell diversity. Processes Rough ER Nerve cell Nucleus (f) Cell that gathers information and controls body functions © 2018 Pearson Education, Ltd.  Cell Diversity ▪ Cells of reproduction ▪ Oocyte (female) ▪ Largest cell in the body ▪ Divides to become an embryo upon fertilization ▪ Sperm (male) ▪ Built for swimming to the egg for fertilization ▪ Flagellum acts as a motile whip © 2018 Pearson Education, Ltd. Figure 3.8g Cell diversity. Nucleus Flagellum Sperm (g) Cell of reproduction © 2018 Pearson Education, Ltd.  Cell Physiology ▪ Cells have the ability to: ▪ Metabolize ▪ Digest food ▪ Dispose of wastes ▪ Reproduce ▪ Grow ▪ Move ▪ Respond to a stimulus © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Solution—homogeneous mixture of two or more components ▪ Solvent—dissolving medium present in the larger quantity; the body’s main solvent is water ▪ Solutes—components in smaller quantities within a solution © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Intracellular fluid ▪ Nucleoplasm and cytosol ▪ Solution containing gases, nutrients, and salts dissolved in water ▪ Extracellular fluid (interstitial fluid) ▪ Fluid on the exterior of the cell ▪ Contains thousands of ingredients, such as nutrients, hormones, neurotransmitters, salts, waste products © 2018 Pearson Education, Ltd.  Membrane Transport ▪ The plasma membrane is a selectively permeable barrier ▪ Some materials can pass through, while others are excluded ▪ For example: ▪ Nutrients can enter the cell ▪ Undesirable substances are kept out © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Two basic methods of transport ▪ Passive processes: substances are transported across the membrane without any input from the cell ▪ Active processes: the cell provides the metabolic energy (ATP) to drive the transport process © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Passive processes: diffusion and filtration ▪ Diffusion ▪ Molecule movement is from high concentration to low concentration, down a concentration gradient ▪ Particles tend to distribute themselves evenly within a solution ▪ Kinetic energy (energy of motion) causes the molecules to move about randomly ▪ Size of the molecule and temperature affect the speed of diffusion © 2018 Pearson Education, Ltd. Figure 3.9 Diffusion. © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Molecules will move by diffusion if any of the following applies: ▪ The molecules are small enough to pass through the membrane’s pores (channels formed by membrane proteins) ▪ The molecules are lipid-soluble ▪ The molecules are assisted by a membrane carrier © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of diffusion ▪ Simple diffusion ▪ An unassisted process ▪ Solutes are lipid-soluble or small enough to pass through membrane pores © 2018 Pearson Education, Ltd. Figure 3.10a Diffusion through the plasma membrane. Extracellular fluid Lipid- soluble solutes Cytoplasm (a) Simple diffusion of lipid-soluble solutes directly through the phospholipid bilayer © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of diffusion (continued) ▪ Osmosis—simple diffusion of water across a selectively permeable membrane ▪ Highly polar water molecules easily cross the plasma membrane through aquaporins ▪ Water moves down its concentration gradient © 2018 Pearson Education, Ltd. Figure 3.10b Diffusion through the plasma membrane. Water molecules (b) Osmosis, diffusion of water through a specific channel protein (aquaporin) © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Osmosis—A Closer Look ▪ Isotonic solutions have the same solute and water concentrations as cells and cause no visible changes in the cell ▪ Hypertonic solutions contain more solutes than the cells do; the cells will begin to shrink ▪ Hypotonic solutions contain fewer solutes (more water) than the cells do; cells will plump © 2018 Pearson Education, Ltd. A Closer Look 3.1 IV Therapy and Cellular “Tonics.” (a) RBC in isotonic solution (b) RBC in hypertonic solution (c) RBC in hypotonic solution © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of diffusion (continued) ▪ Facilitated diffusion ▪ Transports lipid-insoluble and large substances ▪ Glucose is transported via facilitated diffusion ▪ Protein membrane channels or protein molecules that act as carriers are used © 2018 Pearson Education, Ltd. Figure 3.10cd Diffusion through the plasma membrane. Small lipid- Lipid- insoluble insoluble solutes solutes Lipid bilayer (c) Facilitated (d) Facilitated diffusion via diffusion through protein carrier specific for one a channel protein; chemical; binding of substrate mostly ions, causes shape change in selected on basis transport protein of size and charge © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Passive processes ▪ Filtration ▪ Water and solutes are forced through a membrane by fluid, or hydrostatic, pressure ▪ A pressure gradient must exist that pushes solute- containing fluid (filtrate) from a high-pressure area to a lower-pressure area ▪ Filtration is critical for the kidneys to work properly © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Active processes ▪ ATP is used to move substances across a membrane ▪ Active processes are used when: ▪ Substances are too large to travel through membrane channels ▪ The membrane may lack special protein carriers for the transport of certain substances ▪ Substances may not be lipid-soluble ▪ Substances may have to move against a concentration gradient © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Exocytosis ▪ Mechanism cells use to actively secrete hormones, mucus, and other products ▪ Material is carried in a membranous sac called a vesicle that migrates to and combines with the plasma membrane ▪ Contents of vesicle are emptied to the outside ▪ Refer to pathway 1 in Figure 3.6 © 2018 Pearson Education, Ltd. Figure 3.6 Role of the Golgi apparatus in packaging the products of the rough ER. © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Exocytosis (continued) ▪ Exocytosis docking process ▪ Docking proteins on the vesicles recognize plasma membrane proteins and bind with them ▪ Membranes corkscrew and fuse together © 2018 Pearson Education, Ltd. Figure 3.12a Exocytosis. Extracellular Plasma fluid membrane docking protein 1 The membrane- bound vesicle Vesicle migrates to the docking plasma membrane. protein Molecule to be secreted Secretory vesicle Cytoplasm Fusion pore formed 2 There, docking proteins on the vesicle and plasma membrane bind, the vesicle and Fused membrane fuse, and docking a pore opens up. proteins 3 Vesicle contents are released to the cell exterior. (a) The process of exocytosis © 2018 Pearson Education, Ltd. Figure 3.12b Exocytosis. (b) Electron micrograph of a secretory vesicle in exocytosis (190,000×) © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Endocytosis ▪ Extracellular substances are enclosed (engulfed) in a membranous vesicle ▪ Vesicle detaches from the plasma membrane and moves into the cell ▪ Once in the cell, the vesicle typically fuses with a lysosome ▪ Contents are digested by lysosomal enzymes ▪ In some cases, the vesicle is released by exocytosis on the opposite side of the cell © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 1 Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome Release of for digestion. 2A contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle 2B Ingested substance 3 Membranes and receptors (if present) recycled to Pit plasma membrane (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 2 Extracellular fluid Plasma membrane 1 Vesicle forms and fuses with lysosome for digestion. (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 3 Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome for digestion. 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 4 Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome Release of for digestion. 2A contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 5 Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome Release of for digestion. 2A contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle 2B (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Slide 6 Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome Release of for digestion. 2A contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle 2B Ingested substance 3 Membranes and receptors (if present) recycled to Pit plasma membrane (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of endocytosis 1. Phagocytosis—“cell eating” ▪ Cell engulfs large particles such as bacteria or dead body cells ▪ Pseudopods are cytoplasmic extensions that separate substances (such as bacteria or dead body cells) from external environment ▪ Phagocytosis is a protective mechanism, not a means of getting nutrients © 2018 Pearson Education, Ltd. Figure 3.13b Events and types of endocytosis. Cytoplasm Extracellular fluid Bacterium or other particle Pseudopod (b) Phagocytosis © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of endocytosis (continued) 2. Pinocytosis—“cell drinking” ▪ Cell “gulps” droplets of extracellular fluid containing dissolved proteins or fats ▪ Plasma membrane forms a pit, and edges fuse around droplet of fluid ▪ Routine activity for most cells, such as those involved in absorption (small intestine) © 2018 Pearson Education, Ltd. Figure 3.13a Events and types of endocytosis. Extracellular fluid Cytoplasm Plasma membrane Vesicle Lysosome 1 Vesicle forms and fuses with lysosome Release of for digestion. 2A contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle 2B Ingested substance 3 Membranes and receptors (if present) recycled to Pit plasma membrane (a) Endocytosis (pinocytosis) © 2018 Pearson Education, Ltd.  Membrane Transport ▪ Types of endocytosis (continued) 3. Receptor-mediated endocytosis ▪ Method for taking up specific target molecules ▪ Receptor proteins on the membrane surface bind only certain substances ▪ Highly selective process of taking in substances such as enzymes, some hormones, cholesterol, and iron © 2018 Pearson Education, Ltd. Figure 3.13c Events and types of endocytosis. Membrane receptor Target molecule (c) Receptor-mediated endocytosis © 2018 Pearson Education, Ltd.  Cell Division ▪ Cell life cycle is a series of changes the cell experiences from the time it is formed until it divides ▪ Cell life cycle has two major periods 1. Interphase (metabolic phase) ▪ Cell grows and carries on metabolic processes ▪ Longer phase of the cell cycle 2. Cell division ▪ Cell reproduces itself © 2018 Pearson Education, Ltd.  Cell Division ▪ Preparations: DNA Replication ▪ Genetic material is duplicated and readies a cell for division into two cells ▪ Occurs toward the end of interphase © 2018 Pearson Education, Ltd.  Cell Division ▪ Process of DNA replication ▪ DNA uncoils into two nucleotide chains, and each side serves as a template ▪ Nucleotides are complementary ▪ Adenine (A) always bonds with thymine (T) ▪ Guanine (G) always bonds with cytosine (C) ▪ For example, TACTGC bonds with new nucleotides in the order ATGACG © 2018 Pearson Education, Ltd. Figure 3.14 Replication of the DNA molecule at the end of interphase. KEY: Adenine Thymine Cytosine Guanine New Old Newly strand Old (template) (template) synthesized forming strand strand strand DNA of one sister chromatid © 2018 Pearson Education, Ltd.  Cell Division ▪ Events of cell division ▪ Mitosis—division of the nucleus ▪ Results in the formation of two daughter nuclei ▪ Cytokinesis—division of the cytoplasm ▪ Begins when mitosis is near completion ▪ Results in the formation of two daughter cells © 2018 Pearson Education, Ltd.  Cell Division ▪ Events of mitosis: prophase ▪ Chromatin coils into chromosomes; identical strands called chromatids are held together by a centromere ▪ Centrioles direct the assembly of a mitotic spindle ▪ Nuclear envelope and nucleoli have broken down © 2018 Pearson Education, Ltd.  Cell Division ▪ Events of mitosis: metaphase ▪ Chromosomes are aligned in the center of the cell on the metaphase plate (center of the spindle midway between the centrioles) ▪ Straight line of chromosomes is now seen © 2018 Pearson Education, Ltd.  Cell Division ▪ Events of mitosis: anaphase ▪ Centromere splits ▪ Chromatids move slowly apart and toward the opposite ends of the cell ▪ Anaphase is over when the chromosomes stop moving © 2018 Pearson Education, Ltd.  Cell Division ▪ Events of mitosis: telophase ▪ Reverse of prophase ▪ Chromosomes uncoil to become chromatin ▪ Spindles break down and disappear ▪ Nuclear envelope re-forms around chromatin ▪ Nucleoli appear in each of the daughter nuclei © 2018 Pearson Education, Ltd.  Cell Division ▪ Cytokinesis ▪ Division of the cytoplasm ▪ Begins during late anaphase and completes during telophase ▪ A cleavage furrow (contractile ring of microfilaments) forms to pinch the cells into two parts ▪ Two daughter cells exist © 2018 Pearson Education, Ltd.  Cell Division ▪ In most cases, mitosis and cytokinesis occur together ▪ In some cases, the cytoplasm is not divided ▪ Binucleate or multinucleate cells result ▪ Common in the liver and skeletal muscle © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis. Slide 1 Centrioles Chromatin Centrioles Spindle Centromere microtubules Forming mitotic spindle Centromere Plasma Nuclear Chromosome, Fragments of membrane envelope consisting of two nuclear envelope sister chromatids Nucleolus Interphase Early prophase Late prophase Metaphase Nucleolus plate forming Cleavage furrow Nuclear Mitotic Sister Daughter envelope spindle chromatids chromosomes forming Metaphase Anaphase Telophase and cytokinesis © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (1 of 6). Slide 2 Centrioles Chromatin Plasma Nuclear membrane envelope Nucleolus Interphase © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (2 of 6). Slide 3 Centrioles Forming mitotic spindle Centromere Chromosome, consisting of two sister chromatids Early prophase © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (3 of 6). Slide 4 Spindle Centromere microtubules Fragments of nuclear envelope Late prophase © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (4 of 6). Slide 5 Metaphase plate Mitotic Sister spindle chromatids Metaphase © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (5 of 6). Slide 6 Daughter chromosomes Anaphase © 2018 Pearson Education, Ltd. Figure 3.15 Stages of mitosis (6 of 6). Slide 7 Nucleolus forming Cleavage furrow Nuclear envelope forming Telophase and cytokinesis © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ DNA serves as a blueprint for making proteins ▪ Gene: DNA segment that carries a blueprint for building one protein or polypeptide chain ▪ Proteins have many functions ▪ Fibrous (structural) proteins are the building materials for cells ▪ Globular (functional) proteins can act as enzymes (biological catalysts) © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ DNA information is coded into a sequence of bases ▪ A sequence of three bases (triplet) codes for an amino acid ▪ For example, a DNA sequence of AAA specifies the amino acid phenylalanine © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ The role of DNA ▪ Most ribosomes, the manufacturing sites of proteins, are located in the cytoplasm ▪ DNA never leaves the nucleus in interphase cells ▪ DNA requires a decoder and a messenger to carry instructions to build proteins to ribosomes ▪ Both the decoder and messenger functions are carried out by RNA (ribonucleic acid) © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ How does RNA differ from DNA? ▪ RNA is single-stranded ▪ RNA contains ribose sugar instead of deoxyribose ▪ RNA contains uracil (U) base instead of thymine (T) © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Three varieties of RNA ▪ Transfer RNA (tRNA): Transfers appropriate amino acids to the ribosome for building the protein ▪ Ribosomal RNA (rRNA): Helps form the ribosomes where proteins are built ▪ Messenger RNA (mRNA): Carries the instructions for building a protein from the nucleus to the ribosome © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Protein synthesis involves two major phases: ▪ Transcription ▪ Translation ▪ We will detail these two phases next © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Transcription ▪ Transfer of information from DNA’s base sequence to the complementary base sequence of mRNA ▪ DNA is the template for transcription; mRNA is the product ▪ Each DNA triplet corresponds to an mRNA codon ▪ If DNA sequence is AAT-CGT-TCG, then the mRNA corresponding codons are UUA-GCA-AGC © 2018 Pearson Education, Ltd. Figure 3.16a Protein synthesis (1 of 2). Nucleus DNA Cytoplasm (site of transcription) gene (site of translation) 1 mRNA specifying one polypeptide is made from a gene on the DNA template by an enzyme (not shown). 2 mRNA leaves nucleus Amino and attaches to ribosome, mRNA acids and translation begins. Nuclear pore Nuclear membrane Correct amino acid attached to Synthetase each type of enzyme tRNA by an enzyme © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Translation ▪ Base sequence of nucleic acid is translated to an amino acid sequence; amino acids are the building blocks of proteins ▪ Occurs in the cytoplasm and involves three major varieties of RNA © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Translation (continued) ▪ Steps correspond to Figure 3.16 (step 1 covers transcription) ▪ Step 2: mRNA leaves nucleus and attaches to ribosome, and translation begins ▪ Step 3: incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by temporarily binding its anticodon to the codon © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis. Slide 1 Nucleus DNA Cytoplasm (site of transcription) gene (site of translation) 1 mRNA specifying one polypeptide is made from a gene on the DNA template by an enzyme (not shown). 2 mRNA leaves nucleus Amino and attaches to ribosome, mRNA acids and translation begins. Nuclear pore Nuclear membrane Correct amino acid attached to Synthetase each type of enzyme tRNA by an enzyme IIe 3 Incoming tRNA recognizes a complementary Growing mRNA codon calling for its polypeptide amino acid by temporarily Met chain binding its anticodon to the 4 As the ribosome moves Gly codon. along the mRNA, a new amino Ser tRNA “head” acid is added to the growing Phe bearing anticodon protein chain. Ala Peptide bond 5 Released tRNA reenters the cytoplasmic pool, ready to be recharged Large ribosomal subunit with a new amino acid. Codon Direction of ribosome Small ribosomal subunit reading; ribosome Portion of moves the mRNA strand mRNA already along sequentially translated as each codon is read. © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis (1 of 2). Slide 2 Nucleus DNA Cytoplasm (site of transcription) gene (site of translation) 1 mRNA specifying one polypeptide is made from a gene on the DNA template by an enzyme (not shown). Amino mRNA acids Nuclear pore Nuclear membrane Correct amino acid attached to Synthetase each type of enzyme tRNA by an enzyme © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis (1 of 2). Slide 3 Nucleus DNA Cytoplasm (site of transcription) gene (site of translation) 1 mRNA specifying one polypeptide is made from a gene on the DNA template by an enzyme (not shown). 2 mRNA leaves Amino nucleus and attaches to mRNA acids ribosome, and translation begins. Nuclear pore Nuclear membrane Correct amino acid attached to Synthetase each type of enzyme tRNA by an enzyme © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis (2 of 2). Slide 4 IIe 3 Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by temporarily binding its anticodon to the codon. tRNA “head” bearing anticodon Large ribosomal subunit Codon Direction of ribosome Small ribosomal subunit reading; ribosome Portion of moves the mRNA strand mRNA already along sequentially translated as each codon is read. © 2018 Pearson Education, Ltd.  Protein Synthesis ▪ Translation (continued) ▪ Steps correspond to Figure 3.16 ▪ Step 4: as the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain ▪ Step 5: released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis (2 of 2). Slide 5 IIe 3 Incoming tRNA recognizes a complementary Growing mRNA codon calling for its polypeptide amino acid by temporarily Met chain binding its anticodon to the 4 As the ribosome moves along Gly codon. the mRNA, a new amino acid is Ser added to the growing protein tRNA “head” chain. Phe bearing anticodon Ala Peptide bond Large ribosomal subunit Codon Direction of ribosome Small ribosomal subunit reading; ribosome Portion of moves the mRNA strand mRNA already along sequentially translated as each codon is read. © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis (2 of 2). Slide 6 IIe 3 Incoming tRNA recognizes a complementary Growing mRNA codon calling for its polypeptide amino acid by temporarily Met chain binding its anticodon to the 4 As the ribosome moves along Gly codon. the mRNA, a new amino acid is Ser added to the growing protein tRNA “head” chain. Phe bearing anticodon Ala Peptide bond 5 Released tRNA reenters the cytoplasmic pool, ready to be recharged Large ribosomal subunit with a new amino acid. Codon Direction of ribosome Small ribosomal subunit reading; ribosome Portion of moves the mRNA strand mRNA already along sequentially translated as each codon is read. © 2018 Pearson Education, Ltd. Figure 3.16 Protein synthesis. Slide 7 Nucleus DNA Cytoplasm (site of transcription) gene (site of translation) 1 mRNA specifying one polypeptide is made from a gene on the DNA template by an enzyme (not shown). 2 mRNA leaves nucleus Amino and attaches to ribosome, mRNA acids and translation begins. Nuclear pore Nuclear membrane Correct amino acid attached to Synthetase each type of enzyme tRNA by an enzyme IIe 3 Incoming tRNA recognizes a complementary Growing mRNA codon calling for its polypeptide amino acid by temporarily Met chain binding its anticodon to the 4 As the ribosome moves Gly codon. along the mRNA, a new amino Ser tRNA “head” acid is added to the growing Phe bearing anticodon protein chain. Ala Peptide bond 5 Released tRNA reenters the cytoplasmic pool, ready to be recharged Large ribosomal subunit with a new amino acid. Codon Direction of ribosome Small ribosomal subunit reading; ribosome Portion of moves the mRNA strand mRNA already along sequentially translated as each codon is read. © 2018 Pearson Education, Ltd.  Part II: Body Tissues ▪ Tissues ▪ Groups of cells with similar structure and function ▪ Four primary types: 1. Epithelial tissue (epithelium) 2. Connective tissue 3. Muscle tissue 4. Nervous tissue © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Locations: ▪ Body coverings ▪ Body linings ▪ Glandular tissue ▪ Functions: ▪ Protection ▪ Absorption ▪ Filtration ▪ Secretion © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Hallmarks of epithelial tissues: ▪ Cover and line body surfaces ▪ Often form sheets with one free surface, the apical surface, and an anchored surface, the basement membrane ▪ Avascular (no blood supply) ▪ Regenerate easily if well nourished © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Classification of epithelia ▪ Number of cell layers ▪ Simple—one layer ▪ Stratified—more than one layer ▪ Shape of cells ▪ Squamous—flattened, like fish scales ▪ Cuboidal—cube-shaped, like dice ▪ Columnar—shaped like columns © 2018 Pearson Education, Ltd. Figure 3.17a Classification and functions of epithelia. Apical surface Basal Simple surface Apical surface Basal surface Stratified (a) Classification based on number of cell layers © 2018 Pearson Education, Ltd. Figure 3.17b Classification and functions of epithelia. Squamous Cuboidal Columnar (b) Classification based on cell shape © 2018 Pearson Education, Ltd. Figure 3.17c Classification and functions of epithelia. Number of layers Cell shape One layer: simple epithelial More than one layer: stratified tissues epithelial tissues Squamous Diffusion and filtration Secretion in Protection serous membranes Cuboidal Secretion and absorption; ciliated types Protection; these tissue types are rare propel mucus or reproductive cells in humans Columnar Secretion and absorption; ciliated types propel mucus or reproductive cells Transitional No simple transitional epithelium exists Protection; stretching to accommodate distension of urinary structures (c) Function of epithelial tissue related to tissue type © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Simple epithelia ▪ Functions in absorption, secretion, and filtration ▪ Very thin (so not suited for protection) © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Simple squamous epithelium ▪ Single layer of flat cells ▪ Locations—usually forms membranes ▪ Lines air sacs of the lungs ▪ Forms walls of capillaries ▪ Forms serous membranes (serosae) that line and cover organs in ventral cavity ▪ Functions in diffusion, filtration, or secretion in membranes © 2018 Pearson Education, Ltd. Figure 3.18a Types of epithelia and examples of common locations in the body. Air sacs of lungs Nucleus of Nuclei of squamous squamous epithelial cell epithelial cells Basement membrane Photomicrograph: Simple squamous epithelium forming part of the alveolar (a) Diagram: Simple squamous (air sac) walls (275×). © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Simple cuboidal epithelium ▪ Single layer of cubelike cells ▪ Locations ▪ Common in glands and their ducts ▪ Forms walls of kidney tubules ▪ Covers the surface of ovaries ▪ Functions in secretion and absorption; ciliated types propel mucus or reproductive cells © 2018 Pearson Education, Ltd. Figure 3.18b Types of epithelia and examples of common locations in the body. Nucleus of Simple simple cuboidal cuboidal epithelial epithelial cells cell Basement Basement membrane membrane Connective tissue Photomicrograph: Simple cuboidal (b) Diagram: Simple cuboidal epithelium in kidney tubules (250×). © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Simple columnar epithelium ▪ Single layer of tall cells ▪ Goblet cells secrete mucus ▪ Locations ▪ Lining of the digestive tract from stomach to anus ▪ Mucous membranes (mucosae) line body cavities opening to the exterior ▪ Functions in secretion and absorption; ciliated types propel mucus or reproductive cells © 2018 Pearson Education, Ltd. Figure 3.18c Types of epithelia and examples of common locations in the body. Nuclei of simple Mucus of a columnar epithelial cells goblet cell tend to line up Simple columnar epithelial cell Basement Basement membrane membrane Photomicrograph: Simple columnar (c) Diagram: Simple columnar epithelium of the small intestine (575×). © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Pseudostratified columnar epithelium ▪ All cells rest on a basement membrane ▪ Single layer, but some cells are shorter than others giving a false (pseudo) impression of stratification ▪ Location: respiratory tract, where it is ciliated and known as pseudostratified ciliated columnar epithelium ▪ Functions in absorption or secretion © 2018 Pearson Education, Ltd. Figure 3.18d Types of epithelia and examples of common locations in the body. Pseudo- stratified Cilia epithelial layer Pseudostratified Basement epithelial layer membrane Basement Nuclei of membrane pseudostratified cells do not line up Connective tissue Photomicrograph: Pseudostratified (d) Diagram: Pseudostratified (ciliated) ciliated columnar epithelium lining columnar the human trachea (560×). © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Stratified epithelia ▪ Consist of two or more cell layers ▪ Function primarily in protection © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Stratified squamous epithelium ▪ Most common stratified epithelium ▪ Named for cells present at the free (apical) surface, which are squamous ▪ Functions as a protective covering where friction is common ▪ Locations—lining of the: ▪ Skin (outer portion) ▪ Mouth ▪ Esophagus © 2018 Pearson Education, Ltd. Figure 3.18e Types of epithelia and examples of common locations in the body. Nuclei Stratified squamous epithelium Stratified squamous epithelium Basement Basement membrane membrane Connective Photomicrograph: Stratified tissue squamous epithelium lining of (e) Diagram: Stratified squamous the esophagus (140×). © 2018 Pearson Education, Ltd.  Epithelial Tissue ▪ Stratified cuboidal epithelium—two layers of cuboidal cells; functions in protection ▪ Stratified columnar epithelium—surface cells are columnar, and cells underneath vary in size and shape; functions in