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PowerPoint® Lecture Slides Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College CHAPTER 3 Cells and Tissues © 2012 Pearson Education, Inc. Concepts of the Cell Theory (no notes) •A cell is the basic structural and functional unit of living organisms. •The activity of an organism depends on the collective activities of its cells. •According to the principle of complementarity, the biochemical activities of cells are dictated by the relative number of their specific subcellular structures. •Continuity of life has a cellular basis. © 2012 Pearson Education, Inc. Chemical Components of Cells (no notes) •Most cells are composed of the following four elements •Carbon •Hydrogen •Oxygen •Nitrogen © 2012 Pearson Education, Inc. Cells and Tissues •1. Carry out all chemical activities needed to sustain life •2. Cells are the building blocks of all living things. •3. Tissues are groups of cells that are similar in structure and function. © 2012 Pearson Education, Inc. Anatomy of the Cell •1. Cells are not all the same. •2. All cells share general structures. •3. All cells have three main regions •Nucleus •Cytoplasm •Plasma membrane © 2012 Pearson Education, Inc. Nucleus Cytoplasm Plasma membrane (a) © 2012 Pearson Education, Inc. Figure 3.1a The Nucleus •1. Control center of the cell •Contains genetic material (DNA) •2. Three regions •Nuclear envelope (membrane) •Nucleolus •Chromatin © 2012 Pearson Education, Inc. Nuclear envelope Chromatin Nucleolus Nucleus Nuclear pores Rough ER (b) © 2012 Pearson Education, Inc. Figure 3.1b The Nucleus •Nuclear envelope (membrane) •1. Barrier of the nucleus •2. Consists of a double bilayer membrane •3. Contains nuclear pores that allow for exchange of material with the rest of the cell © 2012 Pearson Education, Inc. The Nucleus •Nucleoli •1. Nucleus contains one or more nucleoli and are the site of ribosome assembly •2. Ribosomes migrate into the cytoplasm through nuclear pores © 2012 Pearson Education, Inc. Plasma Membrane •1. Barrier for cell contents •2. Double phospholipid layer •Hydrophilic heads (water-loving) •Hydrophobic tails (water-hating) •3. Also contains proteins, cholesterol, and glycoproteins © 2012 Pearson Education, Inc. Extracellular fluid (watery environment) Glycoprotein Glycolipid Cholesterol Sugar group Polar heads of phospholipid molecules Bimolecular lipid layer containing proteins Nonpolar tails of phospholipid molecules © 2012 Pearson Education, Inc. Channel Proteins Filaments of cytoskeleton Cytoplasm (watery environment) Figure 3.2 Microvilli Tight (impermeable) junction Desmosome (anchoring junction) Plasma membranes of adjacent cells Connexon Gap Underlying Extracellular basement space between (communicating) junction membrane cells © 2012 Pearson Education, Inc. Figure 3.3 Cytoplasm •1.Contains three major elements •A. Cytosol •Fluid that suspends other elements •B. Organelles •Metabolic machinery of the cell •“Little organs” that perform functions for the cell •C. Inclusions •Chemical substances such as stored nutrients or cell products © 2012 Pearson Education, Inc. Chromatin Nuclear envelope Nucleolus Nucleus Plasma membrane Smooth endoplasmic reticulum Cytosol Lysosome Mitochondrion Rough endoplasmic reticulum Centrioles Ribosomes Golgi apparatus Secretion being released from cell by exocytosis Microtubule Peroxisome Intermediate filaments © 2012 Pearson Education, Inc. Figure 3.4 Cytoplasmic Organelles •Mitochondria •“Powerhouses” of the cell •Change shape continuously •Carry out reactions where oxygen is used to break down food •Provides ATP for cellular energy © 2012 Pearson Education, Inc. Cytoplasmic Organelles •Ribosomes •Made of protein and RNA •Sites of protein synthesis •Found at two locations •Free in the cytoplasm •As part of the rough endoplasmic reticulum © 2012 Pearson Education, Inc. Cytoplasmic Organelles •Endoplasmic reticulum (ER) •Fluid-filled tubules for carrying substances •Two types of ER •Rough endoplasmic reticulum • Studded with ribosomes • Synthesizes proteins •Smooth endoplasmic reticulum • Functions in lipid metabolism and detoxification of drugs and pesticides © 2012 Pearson Education, Inc. Ribosome mRNA Rough ER 2 1 3 1 As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. 2 In the cistern, 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 Transport vesicle buds off 4 membranous sac called a transport vesicle. 4 The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing. Protein inside transport vesicle © 2012 Pearson Education, Inc. Figure 3.5 Ribosome mRNA Rough ER 1 As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. 1 Protein © 2012 Pearson Education, Inc. Figure 3.5, step 1 Ribosome mRNA Rough ER 2 1 1 As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. 2 In the cistern, the protein folds into its Protein © 2012 Pearson Education, Inc. functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Figure 3.5, step 2 Ribosome mRNA Rough ER 2 1 3 Protein 1 As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. 2 In the cistern, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). 3 The protein is packaged in a tiny Transport vesicle buds off © 2012 Pearson Education, Inc. membranous sac called a transport vesicle. Figure 3.5, step 3 Ribosome mRNA Rough ER 2 1 3 1 As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. 2 In the cistern, 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 Transport vesicle buds off 4 membranous sac called a transport vesicle. 4 The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing. Protein inside transport vesicle © 2012 Pearson Education, Inc. Figure 3.5, step 4 Cytoplasmic Organelles •Golgi apparatus •Modifies and packages proteins •Produces different types of packages •Secretory vesicles •Cell membrane components •Lysosomes © 2012 Pearson Education, Inc. Rough ER Cisterna Proteins in cisterna Membrane Lysosome fuses with ingested substances Transport vesicle Golgi vesicle containing digestive enzymes becomes a lysosome Pathway 3 Pathway 2 Golgi apparatus Pathway 1 Golgi vesicle containing proteins to be secreted becomes a secretory vesicle © 2012 Pearson Education, Inc. Secretory vesicles Proteins Secretion by exocytosis Golgi vesicle containing membrane components fuses with the plasma membrane Plasma membrane Extracellular fluid Figure 3.6 Cytoplasmic Organelles •Lysosomes •Contain enzymes produced by ribosomes •Packaged by the Golgi apparatus •Digest worn-out or nonusable materials within the cell © 2012 Pearson Education, Inc. Cytoplasmic Organelles •Peroxisomes •Membranous sacs of oxidase enzymes •Detoxify harmful substances such as alcohol and formaldehyde •Break down free radicals (highly reactive chemicals) •Replicate by pinching in half © 2012 Pearson Education, Inc. Cytoplasmic Organelles •Cytoskeleton •Network of protein structures that extend throughout the cytoplasm •Provides the cell with an internal framework •Three different types of elements •Microfilaments (largest) •Intermediate filaments •Microtubules (smallest) © 2012 Pearson Education, Inc. (b) Intermediate filaments (a) Microfilaments (c) Microtubules Tubulin subunits Fibrous subunits Actin subunit 7 nm Microfilaments form the blue network surrounding the pink nucleus. © 2012 Pearson Education, Inc. 10 nm Intermediate filaments form the purple batlike network. 25 nm Microtubules appear as gold networks surrounding the cells’ pink nuclei. Figure 3.7a-c Cytoplasmic Organelles •Centrioles •Rod-shaped bodies made of microtubules •Direct the formation of mitotic spindle during cell division © 2012 Pearson Education, Inc. Cellular Projections •Not found in all 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 © 2012 Pearson Education, Inc. Fibroblasts Rough ER and Golgi apparatus No organelles Nucleus Erythrocytes (a) Cells that connect body parts © 2012 Pearson Education, Inc. Figure 3.8a Epithelial cells Nucleus Intermediate filaments (b) Cells that cover and line body organs © 2012 Pearson Education, Inc. Figure 3.8b Skeletal muscle cell Contractile filaments Nuclei Smooth muscle cells (c) Cells that move organs and body parts © 2012 Pearson Education, Inc. Figure 3.8c Fat cell Lipid droplet Nucleus (d) Cell that stores nutrients © 2012 Pearson Education, Inc. Figure 3.8d Lysosomes Macrophage Pseudopods (e) Cell that fights disease © 2012 Pearson Education, Inc. Figure 3.8e Processes Rough ER Nerve cell Nucleus (f) Cell that gathers information and controls body functions © 2012 Pearson Education, Inc. Figure 3.8f Flagellum Nucleus Sperm (g) Cell of reproduction © 2012 Pearson Education, Inc. Figure 3.8g Cell Physiology: Membrane Transport •1. Membrane transport—movement of substances into and out of the cell •Cell membranes are selectively permeable (some substances can pass through but others cannot) •2. Two basic methods of transport •Passive processes •No energy is required •Active processes •Cell must provide metabolic energy (ATP) © 2012 Pearson Education, Inc. Selective Permeability •1. The plasma membrane allows some materials to pass while excluding others. •2. This permeability influences movement both into and out of the cell. © 2012 Pearson Education, Inc. Passive Processes (no notes) •Diffusion •Particles tend to distribute themselves evenly within a solution •Movement is from high concentration to low concentration, or down a concentration gradient © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 3.9 Passive Processes (no notes) •Types of diffusion •Simple diffusion •An unassisted process •Solutes are lipid-soluble materials or small enough to pass through membrane pores © 2012 Pearson Education, Inc. Extracellular fluid Lipidsoluble solutes Cytoplasm (a) Simple diffusion of fat-soluble molecules directly through the phospholipid bilayer © 2012 Pearson Education, Inc. Figure 3.10a Passive Processes (no notes) •Types of diffusion (continued) •Osmosis—simple diffusion of water •Highly polar water molecules easily cross the plasma membrane through aquaporins © 2012 Pearson Education, Inc. Water molecules Lipid bilayer (d) Osmosis, diffusion of water through a specific channel protein (aquaporin) or through the lipid bilayer © 2012 Pearson Education, Inc. Figure 3.10d Passive Processes (no notes) •Facilitated diffusion •Substances require a protein carrier for passive transport •Transports lipid-insoluble and large substances © 2012 Pearson Education, Inc. Lipidinsoluble solutes (b) Carrier-mediated facilitated diffusion via protein carrier specific for one chemical; binding of substrate causes shape change in transport protein © 2012 Pearson Education, Inc. Small lipidinsoluble solutes (c) Channel-mediated facilitated diffusion through a channel protein; mostly ions selected on basis of size and charge Figure 3.10b–c Passive Processes (no notes) •Filtration • Water and solutes are forced through a membrane by fluid, or hydrostatic pressure • A pressure gradient must exist • Solute-containing fluid is pushed from a high-pressure area to a lower pressure area © 2012 Pearson Education, Inc. Active Processes (no notes) •Substances are transported that are unable to pass by diffusion •Substances may be too large •Substances may not be able to dissolve in the fat core of the membrane •Substances may have to move against a concentration gradient •ATP is used for transport © 2012 Pearson Education, Inc. Active Processes (no notes) •Two common forms of active transport •Active transport (solute pumping) •Vesicular transport •Exocytosis •Endocytosis • Phagocytosis • Pinocytosis © 2012 Pearson Education, Inc. Active Processes (no notes) •Active transport (solute pumping) •Amino acids, some sugars, and ions are transported by protein carriers called solute pumps •ATP energizes protein carriers •In most cases, substances are moved against concentration gradients © 2012 Pearson Education, Inc. Extracellular fluid Na+ Na+ K+ Na+ Na+ Na+ K+ P K+ P Na+ ATP 1 2 3 K+ ADP 1 Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP, which causes the pump protein to change its shape. © 2012 Pearson Education, Inc. 2 The shape change expels Na+ to the outside. Extracellular K+ binds, causing release of the phosphate group. 3 Loss of phosphate restores the original conformation of the pump protein. K+ is released to the cytoplasm and Na+ sites are ready to bind Na+ again; the cycle repeats. Cytoplasm Figure 3.11 Extracellular fluid Na+ Na+ P Na+ ATP 1 ADP 1 Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP, which causes the pump protein to change its shape. Cytoplasm © 2012 Pearson Education, Inc. Figure 3.11, step 1 Extracellular fluid Na+ Na+ K+ Na+ Na+ Na+ K+ P P Na+ ATP 1 2 ADP 1 Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP, which causes the pump protein to change its shape. 2 The shape change expels Na+ to the outside. Extracellular K+ binds, causing release of the phosphate group. Cytoplasm © 2012 Pearson Education, Inc. Figure 3.11, step 2 Extracellular fluid Na+ Na+ K+ Na+ Na+ Na+ K+ P K+ P Na+ ATP 1 2 3 K+ ADP 1 Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP, which causes the pump protein to change its shape. © 2012 Pearson Education, Inc. 2 The shape change expels Na+ to the outside. Extracellular K+ binds, causing release of the phosphate group. 3 Loss of phosphate restores the original conformation of the pump protein. K+ is released to the cytoplasm and Na+ sites are ready to bind Na+ again; the cycle repeats. Cytoplasm Figure 3.11, step 3 Active Processes (no notes) •Vesicular transport •Exocytosis •Moves materials out of the cell •Material is carried in a membranous vesicle •Vesicle migrates to plasma membrane •Vesicle combines with plasma membrane •Material is emptied to the outside © 2012 Pearson Education, Inc. Extracellular fluid Plasma membrane SNARE (t-SNARE) Vesicle SNARE (v-SNARE) Molecule to be secreted Secretory vesicle 1 The membranebound vesicle migrates to the plasma membrane. Cytoplasm Fusion pore formed Fused SNAREs 2 There, v-SNAREs bind with t-SNAREs, the vesicle and plasma membrane fuse, and a pore opens up. 3 Vesicle contents are released to the cell exterior. (a) The process of exocytosis © 2012 Pearson Education, Inc. Figure 3.12a © 2012 Pearson Education, Inc. Figure 3.12b Active Processes (no notes) •Vesicular transport (continued) •Endocytosis •Extracellular substances are engulfed by being enclosed in a membranous vescicle •Types of endocytosis •Phagocytosis—“cell eating” •Pinocytosis—“cell drinking” © 2012 Pearson Education, Inc. Extracellular fluid Plasma membrane Lysosome Cytosol Vesicle 1 Vesicle fusing with lysosome for digestion Ingested substance Release of contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle containing ingested material Pit © 2012 Pearson Education, Inc. 3 Membranes and receptors (if present) recycled to plasma membrane Figure 3.13a Extracellular fluid Plasma membrane 1 Vesicle fusing with lysosome for digestion Ingested substance © 2012 Pearson Education, Inc. Figure 3.13a, step 1 Extracellular fluid Plasma membrane Lysosome Cytosol Vesicle 1 Vesicle fusing with lysosome for digestion Ingested substance Release of contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle containing ingested material © 2012 Pearson Education, Inc. Figure 3.13a, step 2 Extracellular fluid Plasma membrane Lysosome Cytosol Vesicle 1 Vesicle fusing with lysosome for digestion Ingested substance Release of contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle containing ingested material Pit © 2012 Pearson Education, Inc. 3 Membranes and receptors (if present) recycled to plasma membrane Figure 3.13a, step 3 Extracellular fluid Cytoplasm Bacterium or other particle Pseudopod (b) © 2012 Pearson Education, Inc. Figure 3.13b Membrane receptor (c) © 2012 Pearson Education, Inc. Figure 3.13c Cell Life Cycle • Cells have two major periods •1. Interphase •Cell grows •Cell carries on metabolic processes •2. Cell division •Cell replicates itself •Function is to produce more cells for growth and repair processes © 2012 Pearson Education, Inc. DNA Replication •1. Genetic material is duplicated and readies a cell for division into two cells •2. Occurs toward the end of interphase •3. DNA uncoils and each side serves as a template © 2012 Pearson Education, Inc. C T G A G C T A Key: C G = Adenine C G T A = Thymine = Cytosine = Guanine T A C G T A C G G G T C A T T A T T C G G T A A C C G © 2012 Pearson Education, Inc. A C G T Old (template) strand T A A T A G C A Newly synthesized strand C G A New Old (template) strand strand forming DNA of one chromatid Figure 3.14 Events of Cell Division •Mitosis— •A. Division of the nucleus •B. Results in the formation of two daughter nuclei •Cytokinesis— •A. division of the cytoplasm •B. Begins when mitosis is near completion •C. Results in the formation of two daughter cells PLAY A&P Flix™: Mitosis © 2012 Pearson Education, Inc. Stages of Mitosis •Prophase •First part of cell division •Centrioles migrate to the poles to direct assembly of mitotic spindle fibers •DNA appears as double-stranded chromosomes •Nuclear envelope breaks down and disappears © 2012 Pearson Education, Inc. Stages of Mitosis •Metaphase •Chromosomes are aligned in the center of the cell on the metaphase plate © 2012 Pearson Education, Inc. Stages of Mitosis •Anaphase •Chromosomes are pulled apart and toward the opposite ends of the cell •Cell begins to elongate © 2012 Pearson Education, Inc. Stages of Mitosis •Telophase •Chromosomes uncoil to become chromatin •Nuclear envelope reforms around chromatin •Spindles break down and disappear © 2012 Pearson Education, Inc. Stages of Mitosis •Cytokinesis •Begins during late anaphase and completes during telophase •A cleavage furrow forms to pinch the cells into two parts © 2012 Pearson Education, Inc. Centrioles Chromatin Centrioles Forming mitotic spindle Plasma membrane Nuclear envelope Nucleolus Interphase Chromosome, consisting of two sister chromatids Early prophase Metaphase plate Spindle microtubules Centromere Centromere Fragments of nuclear envelope Spindle pole Late prophase Nucleolus forming Cleavage furrow Spindle Metaphase © 2012 Pearson Education, Inc. Sister chromatids Daughter chromosomes Anaphase Nuclear envelope forming Telophase and cytokinesis Figure 3.15 Centrioles Plasma membrane Interphase © 2012 Pearson Education, Inc. Chromatin Nuclear envelope Nucleolus Figure 3.15, step 1 Centrioles Forming mitotic spindle Centromere Chromosome, consisting of two sister chromatids Early prophase © 2012 Pearson Education, Inc. Figure 3.15, step 2 Spindle microtubules Centromere Fragments of nuclear envelope Spindle pole Late prophase © 2012 Pearson Education, Inc. Figure 3.15, step 3 Metaphase plate Spindle Sister chromatids Metaphase © 2012 Pearson Education, Inc. Figure 3.15, step 4 Daughter chromosomes Anaphase © 2012 Pearson Education, Inc. Figure 3.15, step 5 Nucleolus forming Cleavage furrow Nuclear envelope forming Telophase and cytokinesis © 2012 Pearson Education, Inc. Figure 3.15, step 6 Protein Synthesis- ?? •1. Gene—DNA segment that carries a blueprint for building one protein •2. Proteins have many functions •Building materials for cells •Act as enzymes (biological catalysts) •3. RNA is essential for protein synthesis © 2012 Pearson Education, Inc. Role 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 © 2012 Pearson Education, Inc. Transcription and Translation •Transcription •Transfer of information from DNA’s base sequence to the complimentary base sequence of mRNA •Three-base sequences on mRNA are called codons © 2012 Pearson Education, Inc. Transcription and Translation •Translation •Base sequence of nucleic acid is translated to an amino acid sequence •Amino acids are the building blocks of proteins © 2012 Pearson Education, Inc. Nucleus (site of transcription) Cytoplasm (site of translation) DNA 1 mRNA specifying one polypeptide is made on DNA template. 2 mRNA leaves nucleus and attaches to ribosome, and translation begins. Amino acids mRNA Nuclear pore Correct amino acid attached to each species of tRNA by an enzyme Nuclear membrane 4 As the ribosome Growing moves along the polypeptide Met mRNA, a new amino chain Gly acid is added to the growing protein chain. Ser Phe Ala 5 Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid. Synthetase enzyme lle 3 Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon. tRNA “head” bearing anticodon Peptide bond Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16 Nucleus (site of transcription) Cytoplasm (site of translation) DNA 1 mRNA specifying one polypeptide is made on DNA template. Amino acids mRNA Nuclear pore Nuclear membrane Correct amino acid attached to each species of tRNA by an enzyme Met Gly Growing polypeptide chain Synthetase enzyme lle Ser Phe Ala Peptide bond tRNA “head” bearing anticodon Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16, step 1 Nucleus (site of transcription) Cytoplasm (site of translation) DNA 1 mRNA specifying one polypeptide is made on DNA template. 2 mRNA leaves nucleus and attaches to ribosome, and translation begins. Amino acids mRNA Nuclear pore Nuclear membrane Correct amino acid attached to each species of tRNA by an enzyme Met Gly Growing polypeptide chain Synthetase enzyme lle Ser Phe Ala Peptide bond tRNA “head” bearing anticodon Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16, step 2 Nucleus (site of transcription) Cytoplasm (site of translation) DNA 1 mRNA specifying one polypeptide is made on DNA template. 2 mRNA leaves nucleus and attaches to ribosome, and translation begins. Amino acids mRNA Nuclear pore Nuclear membrane Correct amino acid attached to each species of tRNA by an enzyme Met Gly Growing polypeptide chain Synthetase enzyme lle 3 Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon. tRNA “head” bearing anticodon Ser Phe Ala Peptide bond Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16, step 3 Nucleus (site of transcription) Cytoplasm (site of translation) DNA 1 mRNA specifying one polypeptide is made on DNA template. 2 mRNA leaves nucleus and attaches to ribosome, and translation begins. Amino acids mRNA Nuclear pore Nuclear membrane Correct amino acid attached to each species of tRNA by an enzyme 4 As the ribosome Growing moves along the polypeptide Met mRNA, a new amino chain Gly acid is added to the growing protein chain. Ser Phe Ala Synthetase enzyme lle 3 Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon. tRNA “head” bearing anticodon Peptide bond Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16, step 4 Nucleus (site of transcription) DNA Cytoplasm (site of translation) 1 mRNA specifying one polypeptide is made on DNA template. 2 mRNA leaves nucleus and attaches to ribosome, and translation begins. Amino acids mRNA Nuclear pore Correct amino acid attached to each species of tRNA by an enzyme Nuclear membrane 4 As the ribosome Growing moves along the polypeptide Met mRNA, a new amino chain Gly acid is added to the growing protein chain. Ser Phe Ala 5 Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid. Synthetase enzyme lle 3 Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon. tRNA “head” bearing anticodon Peptide bond Large ribosomal subunit C G G G C C A U A G U C Codon Direction of ribosome advance; ribosome Portion of Small ribosomal subunit moves the mRNA strand along sequentially mRNA already as each codon is read. translated © 2012 Pearson Education, Inc. Figure 3.16, step 5 Body Tissues •Tissues •Groups of cells with similar structure and function •Four primary types •Epithelial tissue (epithelium) •Connective tissue •Muscle tissue •Nervous tissue © 2012 Pearson Education, Inc. Epithelial Tissues •Locations •Body coverings •Body linings •Glandular tissue •Functions •Protection •Absorption •Filtration •Secretion © 2012 Pearson Education, Inc. Epithelium Characteristics •Cells fit closely together and often form sheets •The apical surface is the free surface of the tissue •The lower surface of the epithelium rests on a basement membrane •Avascular (no blood supply) •Regenerate easily if well nourished © 2012 Pearson Education, Inc. Apical surface Basal surface Simple Apical surface Basal surface Stratified (a) Classification based on number of cell layers © 2012 Pearson Education, Inc. Figure 3.17a Classification of Epithelia •Number of cell layers •Simple—one layer •Stratified—more than one layer © 2012 Pearson Education, Inc. Apical surface Basal surface Simple Apical surface Basal surface Stratified (a) Classification based on number of cell layers © 2012 Pearson Education, Inc. Figure 3.17a Classification of Epithelia •Shape of cells •Squamous •flattened •Cuboidal •cube-shaped •Columnar •column-like © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 3.17b Simple Epithelia •Simple squamous •Single layer of flat cells •Location - usually forms membranes •Lines body cavities •Lines lungs and capillaries •Functions in diffusion, filtration, or secretion in membranes © 2012 Pearson Education, Inc. Air sacs of lungs Nucleus of squamous epithelial cell Basement membrane (a) Diagram: Simple squamous © 2012 Pearson Education, Inc. Nuclei of squamous epithelial cells Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (185×). Figure 3.18a Simple Epithelia •Simple cuboidal •Single layer of cube-like cells •Locations •Common in glands and their ducts •Forms walls of kidney tubules •Covers the ovaries •Functions in secretion and absorption; ciliated types propel mucus or reproductive cells © 2012 Pearson Education, Inc. Simple cuboidal epithelial cells Nucleus of simple cuboidal epithelial cell Basement membrane Basement membrane Connective tissue (b) Diagram: Simple cuboidal © 2012 Pearson Education, Inc. Photomicrograph: Simple cuboidal epithelium in kidney tubules (250×). Figure 3.18b Simple Epithelia •Simple columnar •Single layer of tall cells •Often includes mucus-producing goblet cells •Location - lines digestive tract •Functions in secretion and absorption; ciliated types propel mucus or reproductive cells © 2012 Pearson Education, Inc. Simple columnar epithelial cell Nucleus of simple columnar epithelial cell Goblet cell Basement membrane Connective tissue Basement membrane (c) Diagram: Simple columnar © 2012 Pearson Education, Inc. Photomicrograph: Simple columnar epithelium of the small intestine (430×). Figure 3.18c Simple Epithelia •Pseudostratified columnar •Single layer, but some cells are shorter than others •Often looks like a double layer of cells but all cells rest on the basement membrane •Location - respiratory tract, where it is ciliated •Functions in absorption or secretion © 2012 Pearson Education, Inc. Cilia Pseudostratified epithelial layer Pseudostratified epithelial layer Basement membrane (d) Diagram: Pseudostratified (ciliated) columnar © 2012 Pearson Education, Inc. Basement membrane Connective tissue Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (430×). Figure 3.18d Stratified Epithelia •Stratified squamous •Cells at the apical surface are flattened •Functions as a protective covering where friction is common •Locations - lining of the: •Skin •Mouth •Esophagus © 2012 Pearson Education, Inc. Nuclei Stratified squamous epithelium Stratified squamous epithelium Basement membrane (e) Diagram: Stratified squamous © 2012 Pearson Education, Inc. Photomicrograph: Stratified squamous epithelium lining of the esophagus (140×). Basement membrane Connective tissue Figure 3.18e Stratified Epithelia •Stratified cuboidal—two layers of cuboidal cells; functions in protection •Stratified columnar—surface cells are columnar, cells underneath vary in size and shape; functions in protection •Stratified cuboidal and columnar •Rare in human body •Found mainly in ducts of large glands © 2012 Pearson Education, Inc. Stratified Epithelia •Transitional epithelium •Composed of modified stratified squamous epithelium •Shape of cells depends upon the amount of stretching •Functions in stretching and the ability to return to normal shape •Location - lines organs of the urinary system © 2012 Pearson Education, Inc. Basement membrane Transitional epithelium Basement membrane Transitional epithelium Connective tissue (f) Diagram: Transitional © 2012 Pearson Education, Inc. Photomicrograph: Transitional epithelium lining of the bladder, relaxed state (215×); surface rounded cells flatten and elongate when the bladder fills with urine. Figure 3.18f Glandular Epithelium •Gland •One or more cells responsible for secreting a particular product •Secretions contain protein molecules in an aqueous (water-based) fluid © 2012 Pearson Education, Inc. Glandular Epithelium •Two major gland types •Endocrine gland •Ductless since secretions diffuse into blood vessels •All secretions are hormones •Exocrine gland •Secretions empty through ducts to the epithelial surface •Include sweat and oil glands © 2012 Pearson Education, Inc. Connective Tissue •Found everywhere in the body •Includes the most abundant and widely distributed tissues •Functions •Binds body tissues together •Supports the body •Provides protection © 2012 Pearson Education, Inc. Connective Tissue Characteristics •Variations in blood supply •Some tissue types are well vascularized •Some have a poor blood supply or are avascular •Extracellular matrix •Non-living material that surrounds living cells © 2012 Pearson Education, Inc. Extracellular Matrix •Two main elements •Ground substance—mostly water along with adhesion proteins and polysaccharide molecules •Fibers •Produced by the cells •Three types • Collagen (white) fibers • Elastic (yellow) fibers • Reticular fibers © 2012 Pearson Education, Inc. Connective Tissue Types •Bone (osseous tissue) •Composed of •Bone cells in lacunae (cavities) •Hard matrix of calcium salts •Large numbers of collagen fibers •Functions to protect and support the body © 2012 Pearson Education, Inc. Bone cells in lacunae Central canal Lacunae Lamella (a) Diagram: Bone © 2012 Pearson Education, Inc. Photomicrograph: Cross-sectional view of ground bone (300×). Figure 3.19a Connective Tissue Types •Hyaline cartilage •Most common type of cartilage •Composed of •Abundant collagen fibers •Rubbery matrix •Locations •Larynx •Entire fetal skeleton prior to birth •Functions as a more flexible skeletal element than bone © 2012 Pearson Education, Inc. Chondrocyte (Cartilage cell) Chondrocyte in lacuna Lacunae Matrix (b) Diagram: Hyaline cartilage © 2012 Pearson Education, Inc. Photomicrograph: Hyaline cartilage from the trachea (500×). Figure 3.19b Connective Tissue Types •Elastic cartilage •Provides elasticity •Location •Supports the external ear •Fibrocartilage •Highly compressible •Location •Forms cushion-like discs between vertebrae © 2012 Pearson Education, Inc. Chondrocytes in lacunae Chondrocites in lacunae Collagen fiber Collagen fibers (c) Diagram: Fibrocartilage © 2012 Pearson Education, Inc. Photomicrograph: Fibrocartilage of an intervertebral disc (110×). Figure 3.19c Connective Tissue Types •Dense connective tissue (dense fibrous tissue) •Main matrix element is collagen fiber •Fibroblasts are cells that make fibers •Locations •Tendons—attach skeletal muscle to bone •Ligaments—attach bone to bone at joints •Dermis—lower layers of the skin © 2012 Pearson Education, Inc. Ligament Tendon Collagen fibers Collagen fibers Nuclei of fibroblasts Nuclei of fibroblasts (d) Diagram: Dense fibrous © 2012 Pearson Education, Inc. Photomicrograph: Dense fibrous connective tissue from a tendon (500×). Figure 3.19d Connective Tissue Types •Loose connective tissue types •Areolar tissue •Most widely distributed connective tissue •Soft, pliable tissue like “cobwebs” •Functions as a packing tissue •Contains all fiber types •Can soak up excess fluid (causes edema) © 2012 Pearson Education, Inc. Mucosa epithelium Lamina propria Elastic fibers Collagen fibers Fibroblast nuclei Fibers of matrix Nuclei of fibroblasts (e) Diagram: Areolar © 2012 Pearson Education, Inc. Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (300×). Figure 3.19e Connective Tissue Types •Loose connective tissue types •Adipose tissue •Matrix is an areolar tissue in which fat globules predominate •Many cells contain large lipid deposits •Functions • Insulates the body • Protects some organs • Serves as a site of fuel storage © 2012 Pearson Education, Inc. Nuclei of fat cells Vacuole containing fat droplet Nuclei of fat cells Vacuole containing fat droplet (f) Diagram: Adipose © 2012 Pearson Education, Inc. Photomicrograph: Adipose tissue from the subcutaneous layer beneath the skin (430×). Figure 3.19f Connective Tissue Types •Loose connective tissue types •Reticular connective tissue •Delicate network of interwoven fibers •Locations • Forms stroma (internal supporting network) of lymphoid organs • Lymph nodes • Spleen • Bone marrow © 2012 Pearson Education, Inc. Spleen White blood cell (lymphocyte) Reticular cell Blood cell Reticular fibers Reticular fibers (g) Diagram: Reticular © 2012 Pearson Education, Inc. Photomicrograph: Dark-staining network of reticular connective tissue (430×). Figure 3.19g Connective Tissue Types •Blood (vascular tissue) •Blood cells surrounded by fluid matrix called blood plasma •Fibers are visible during clotting •Functions as the transport vehicle for materials © 2012 Pearson Education, Inc. Blood cells in capillary Neutrophil (white blood cell) White blood cell Red blood cells Red blood cells Monocyte (white blood cell) (h) Diagram: Blood © 2012 Pearson Education, Inc. Photomicrograph: Smear of human blood (1300×) Figure 3.19h Muscle Tissue •Function is to produce movement •Three types •Skeletal muscle •Cardiac muscle •Smooth muscle © 2012 Pearson Education, Inc. Muscle Tissue Types •Skeletal muscle •Under voluntary control •Contracts to pull on bones or skin •Produces gross body movements or facial expressions •Characteristics of skeletal muscle cells •Striated •Multinucleate (more than one nucleus) •Long, cylindrical cells © 2012 Pearson Education, Inc. Nuclei Part of muscle fiber (a) Diagram: Skeletal muscle © 2012 Pearson Education, Inc. Photomicrograph: Skeletal muscle (approx. 300×). Figure 3.20a Muscle Tissue Types •Cardiac muscle •Under involuntary control •Found only in the heart •Function is to pump blood •Characteristics of cardiac muscle cells •Striated •One nucleus per cell •Cells are attached to other cardiac muscle cells at intercalated disks © 2012 Pearson Education, Inc. Intercalated discs Nucleus (b) Diagram: Cardiac muscle © 2012 Pearson Education, Inc. Photomicrograph: Cardiac muscle (430×). Figure 3.20b Muscle Tissue Types •Smooth muscle •Under involuntary muscle •Found in walls of hollow organs such as stomach, uterus, and blood vessels •Characteristics of smooth muscle cells •No visible striations •One nucleus per cell •Spindle-shaped cells © 2012 Pearson Education, Inc. Smooth muscle cell Nuclei (c) Diagram: Smooth muscle © 2012 Pearson Education, Inc. Photomicrograph: Sheet of smooth muscle (approx. 300×). Figure 3.20c Nervous Tissue •Composed of neurons and nerve support cells •Function is to send impulses to other areas of the body •Irritability •Conductivity •Support cells called neuroglia insulate, protect, and support neurons © 2012 Pearson Education, Inc. Brain Nuclei of supporting cells Spinal cord Cell body of neuron Nuclei of supporting cells Cell body of neuron Neuron processes Neuron processes Diagram: Nervous tissue © 2012 Pearson Education, Inc. Photomicrograph: Neurons (150×) Figure 3.21 Nervous tissue: Internal communication • Brain, spinal cord, and nerves Muscle tissue: Contracts to cause movement • Muscles attached to bones (skeletal) • Muscles of heart (cardiac) • Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters • Lining of GI tract organs and other hollow organs • Skin surface (epidermis) Connective tissue: Supports, protects, binds other tissues together • Bones • Tendons • Fat and other soft padding tissue © 2012 Pearson Education, Inc. Figure 3.22 Tissue Repair (Wound Healing) •Regeneration •Replacement of destroyed tissue by the same kind of cells •Fibrosis •Repair by dense (fibrous) connective tissue (scar tissue) •Whether regeneration or fibrosis occurs depends on: •Type of tissue damaged •Severity of the injury © 2012 Pearson Education, Inc. Events in Tissue Repair •Inflammation •Capillaries become very permeable •Clotting proteins migrate into the area from the blood stream •A clot walls off the injured area •Granulation tissue forms •Growth of new capillaries •Rebuild collagen fibers •Regeneration of surface epithelium •Scab detaches © 2012 Pearson Education, Inc. Regeneration of Tissues •Tissues that regenerate easily •Epithelial tissue (skin and mucous membranes) •Fibrous connective tissues and bone •Tissues that regenerate poorly •Skeletal muscle •Tissues that are replaced largely with scar tissue •Cardiac muscle •Nervous tissue within the brain and spinal cord © 2012 Pearson Education, Inc. Developmental Aspects of Tissue •Epithelial tissue arises from all three primary germ layers •Muscle and connective tissue arise from the mesoderm •Nervous tissue arises from the ectoderm •With old age, there is a decrease in mass and viability in most tissues © 2012 Pearson Education, Inc.