Week 3 Prokaryotic and Eukaryotic Cells Student W2023 PDF

3/3/2023 UNIT 1 WEEK 2a PROKARYOTIC CELLS Some material taken from 1 KEY CONCEPTS REVIEW GENERAL PRINCIPLES OF MICROSCOPY TYPES OF MICROSCOPY © 2012 Pearson Education Inc. 2 1 3/3/2023 Organic Macromolecules - Background Functional Groups – Contain carbon and hydrogen atoms – Atoms often appear in a...

3/3/2023 UNIT 1 WEEK 2a PROKARYOTIC CELLS Some material taken from 1 KEY CONCEPTS REVIEW GENERAL PRINCIPLES OF MICROSCOPY TYPES OF MICROSCOPY © 2012 Pearson Education Inc. 2 1 3/3/2023 Organic Macromolecules - Background Functional Groups – Contain carbon and hydrogen atoms – Atoms often appear in arrangements called functional groups. – Macromolecules—large molecules used by all organisms: – Lipids – Carbohydrates – Proteins – Nucleic acids – Monomers—basic building blocks of macromolecules © 2012 Pearson Education Inc. 3 Organic Macromolecules © 2012 Pearson Education Inc. 4 2 3/3/2023 Cell Theory Cells are the smallest living units of all living organisms. Cells arise only by division of a previously existing cell. Cells: are self assembling, self- replicating, self regulating systems composed of biomolecules operating in concert with one another Unicellular: a single cell performs all functions required to maintain & reproduce itself 5 Processes of Life Growth Reproduction Responsiveness Metabolism © 2012 Pearson Education Inc. 6 3 3/3/2023 Prokaryotic Cells: An Overview Prokaryotes – Belong to two taxa: Domain Archaea and Domain Bacteria – Lack nucleus – Make proteins simultaneously to reading the genetic code – Lack various internal structures bound with phospholipid membranes – Are small (~1.0 µm in diameter) – Have a simple structure © 2012 Pearson Education Inc. 7 Prokaryotic Cell: 8 4 3/3/2023 Common Features Between Prokaryotes And Eukaryotes 9 Bacterial Cell Walls Bacterial Cell Walls – Provide structure and shape and protect cell from osmotic forces – Assist some cells in attaching to other cells or in resisting antimicrobial drugs – Can target cell wall of bacteria with antibiotics – Give bacterial cells characteristic shapes (cocci or bacilli) – Composed of peptidoglycan – Scientists describe two basic types of bacterial cell walls, Gram-positive and Gram-negative © 2012 Pearson Education Inc. 10 5 3/3/2023 Figure 3.13 Comparison of the structures of glucose, NAG, and NAM-overview Glucose N-acetylglucosamine NAG N-acetylmuramic acid NAM 11 Bacterial Cytoplasmic Membranes Membrane Structure – Referred to as phospholipid bilayer – Composed of lipids and associated proteins – Similar to eukaryotic cells – Contain integral and peripheral proteins © 2012 Pearson Education Inc. 12 6 3/3/2023 What is a phospholipid? See Figure 2.16 A phospholipid contains a pair of fatty acid chains and a phosphate group attached to a glycerol backbone. 13 Sterols In The Membrane a. Steroids are lipids characterized by four fused carbon rings. b. Cholesterol in the membrane. Note: How the polar (water-soluble, hydrophillic) head of the phospholipid faces out and the non-polar fatty acid hydrophobic tails hang inside. 14 7 3/3/2023 Membrane showing integral and peripheral proteins Head, which contains phosphate (hydrophilic) Phospholipid Tail (hydrophobic) Integral proteins Cytoplasm Integral protein Phospholipid bilayer Peripheral protein Integral protein Figure 3.16 The structure of a prokaryotic cytoplasmic membrane: a phospholipid bilayer 15 Bacterial Cytoplasmic Membranes Membrane Function – – – – – Produces molecules for energy storage Harvest light energy in photosynthetic bacteria Selectively permeable Naturally impermeable to most substances Proteins allow substances to cross membrane by functioning as pores, channels or carriers – Maintain concentration and electrical gradient © 2012 Pearson Education Inc. 16 8 3/3/2023 Figure 3.17 Electrical potential of a cytoplasmic membrane Cell exterior (extracellular fluid) Cytoplasmic membrane Integral protein Protein DNA Protein Cell interior (cytoplasm) 17 Bacterial Cytoplasmic Membranes Movement Across A Membrane 1. Passive Transport – Passive processes – no ATP required  Diffusion  Facilitated diffusion  Osmosis 2. Active Transport © 2012 Pearson Education Inc. 18 9 3/3/2023 Figure 3.18 Passive processes of movement across a cytoplasmic membrane-overview Extracellular fluid Cytoplasm Diffusion through the phospholipid bilayer Facilitated diffusion through a nonspecific channel protein Facilitated diffusion through a permease specific for one chemical; binding of substrate causes shape change in the channel protein Osmosis, the diffusion of water through a specific channel protein or through the phospholipid bilayer 19 Bacterial Cytoplasmic Membranes Active Transport – ATP required – Molecules move against concentration gradient, substance chemically modified during transport © 2012 Pearson Education Inc. 20 10 3/3/2023 Figure 3.21 Mechanisms of active transport-overview Extracellular fluid Uniport Cytoplasmic membrane Symport Cytoplasm Uniport Antiport Coupled transport: uniport and symport 21 Bacterial Cytoplasmic Membranes Tell Me Why – When the bacterium Escherichia coli is grown in a hypertonic solution, it turns on a gene to synthesize a protein that transports potassium into the cell. Why? 22 11 3/3/2023 Figure 3.21 Effects of isotonic, hypertonic, and hypotonic solutions on cells. 23 Cytoplasm of Bacteria Cytosol (cytoplasm) -viscous fluid -most metabolic reactions occur here -80% water + 20% soluble substances (nutrients, waste) © 2012 Pearson Education Inc. 24 12 3/3/2023 Nucleoid of Bacteria Nucleoid  DNA double stranded molecule, lacks histones  contains genetic material for cell  suspended in cytosol  function: control center of cell  controls reproduction and metabolism © 2012 Pearson Education Inc. 25 26 13 3/3/2023 Plasmids of Bacteria Plasmids Small circles of DNA Not connected to the nucleoid Functions: contains genetic information that is not essential to the cell’s survival may contain genes for R factors (drug resistance), toxins may be involved in conjugation used in genetic engineering research © 2012 Pearson Education Inc. 27 Components of Bacteria Cells 1. Ribosomes - Differ from eukaryotic ribosomes in size (70S) and number of proteins - Difference between ribosomes is important when considering antibacterial drugs( UNIT 3) - Sites of protein synthesis - Consist of 2 subunits – large (50S) and small (30S) 2. Nutrient Storage Granules (Inclusions) and Vacuoles - Scattered throughout cytoplasm - Store nutrients © 2012 Pearson Education Inc. 28 14 3/3/2023 Ribosomes 29 Vacuole 30 15 3/3/2023 Figure 3.23 Granules of PHB in Azotobacter chroococcum Polyhydroxybutyrate 31 Endospores – ensures survival of cell Defensive strategy against hostile or unfavorable conditions Vegetative cell transforms into an endospore when there is a limited supply of nutrients Sporulation requires 8-10 hours Remains viable but dormant after vegetative cell dies Will germinant when introduced into a favorable environment Endospore can form centrally, subterminally or terminally 32 16 3/3/2023 Figure 3.25 Formation of an endospore. 33 External Structures of Bacterial Cells Glycocalycx – “Sugar Cup” Gelatinous, sticky substance secreted by the cell, adheres to the cell wall Composed of polysaccharides, polypeptides, or both Feature of pathogenic bacteria Will absorb dyes, need special staining (will discuss later) Two Types of Glycocalycx Capsule Slime layer © 2012 Pearson Education Inc. 34 17 3/3/2023 External Structures of Bacterial Cells Capsule Composed of organized repeating units of organic chemicals Firmly attached to cell surface May prevent bacteria from being recognized by host, protects the bacteria from phagocytes Enhances the bacteria’s ability to produce disease Slime layer Loosely attached to cell surface Water soluble Sticky layer allows prokaryotes to attach to surfaces © 2012 Pearson Education Inc. 35 Capsule and slime layer also protect the cell from dehydration. Glycocalyx (capsule) Glycocalyx (slime layer) Figure 3.5 Glycocalyces-overview 36 18 3/3/2023 37 External Structures of Bacterial Cells Flagella – Are responsible for movement – Have long structures that extend beyond cell surface – Are not present on all bacteria – Protein composition - flagellin – Bacteria flagella are composed of 3 parts: a long filament, a hook and a basal body – Basal body anchors filament and hook to cell wall by a rod and a series of either two or four rings of integral proteins © 2012 Pearson Education Inc. 38 19 3/3/2023 Figure 3.6 Proximal structure of bacterial flagella-overview Filament Rings allow filament to rotate 360 degrees. Direction of rotation during run Rod Peptidoglycan layer (cell wall) Protein rings Cytoplasmic membrane Cytoplasm Bacteria can be classified by the flagella. Filament Gram  Outer protein rings Rod Gram  Basal body Outer membrane Peptidoglycan layer Integral protein Inner protein rings Cytoplasm Cell wall Cytoplasmic membrane Integral protein 39 Flagella Arrangement A. Monotrichous Bacterium that have a single flagellum B. Lophotrichous A bacterium having two or more flagella at one end 40 20 3/3/2023 Flagella Arrangement C. Amphitrichous A bacterium that has flagella at opposite ends of the cell, also called polar flagella D. Peritrichous A bacterium that has multiple flagella, located at many areas on the cell 41 Figure 3.7 Micrographs of basic arrangements of bacterial flagella-overview 42 21 3/3/2023 External Structures of Bacterial Cells Flagella – Function – Rotation propels bacterium through environment – Flagella rotate at more than 100,000 rpm – Rotation reversible; can be counterclockwise or clockwise – Bacteria move in response to stimuli (taxis) – Runs  movement of cell in one direction – Tumbles  abrupt, random changes in direction © 2012 Pearson Education Inc. 43 Figure 3.9 Motion of a peritrichous bacterium Attractant Counter clockwise rotation produces runs. Clockwise rotation produces tumbles Tumble Run Run Tumble https://www.youtube.com/watch?v=4hexn-DtSt4 44 22 3/3/2023 External Structures of Bacterial Cells Movement of cell in response to stimuli is called taxis  Phototaxis – light stimuli  Chemotaxis – chemical stimuli What is positive taxis? What is negative taxis? © 2012 Pearson Education Inc. 45 External Structures of Bacterial Cells Fimbriae and Pili – Rodlike proteinaceous extensions – Shorter than flagella – Fimbriae  sticky bristle like projection, used to adhere to one another and substances in the environment. Ex. Neisseria gonorrhoeae – Special type of fimbriae – pilus © 2012 Pearson Education Inc. 46 23 3/3/2023 Figure 3.10 Fimbriae Flagellum Fimbria 47 External Structures of Bacterial Cells Pili – Special type of fimbria – Also known as conjugation pili – Longer than other fimbriae but shorter than flagella – Bacteria typically have only one or two per cell – Mediate the transfer of DNA from one cell to another (conjugation) © 2012 Pearson Education Inc. 48 24 3/3/2023 Conjugation Pili: 49 Figure 3.11 Pili Conjugation pilus 50 25 3/3/2023 Other Classifications You learned about taxonomy and how organisms are classified K P C O F G S 51 Binomial Nomenclature Double name given to all organisms Name can be based on scientist name, habitat, etc…. Two parts to name: Genus – only first letter of genus name capitalized, group closely related to organisms Species – lower case letters only, group of identical organisms Ex. Homo sapiens Compare Homo erectus To Homo sapiens -Genus “Homo” means they are closely related! 52 26 3/3/2023 Binomial Nomenclature Examples: 1. Staphylococcus epidermis Meaning: grape-like clusters / skin 2. Escherichia coli Meaning: German biologist / colon 53 Binomial Nomenclature Name is printed in italics or underlined!! Ex.. Escherichia coli Strains can also be used to identify organisms E.coli H 157 E.Coli – genus species H strain 157 substrain 54 27 3/3/2023 Other Classifications Organisms can also be classified by:  Size  Shape  Arrangement  Colour of colony  Habitat  Nutritional requirements  Disease  Researcher 55 FOCUS IN YOUR LAB WORK CELL MORPHOLOGY COLONY MORPHOLOGY WHAT YOU SEE IN THE MICROSCOPE WHAT YOU SEE WITH YOUR NAKED EYE 56 28 3/3/2023 FOCUS IN YOUR LAB WORK CELL MORPHOLOGY COLONY MORPHOLOGY Shape Arrangement Size (actual estimate) Shape (different descriptors than cell morphology) Margin Elevation Size Texture Appearance Pigmentation Optical Property 57 Cell Morphology: Cell Shape/Arrangement/Size 1. Cocci (us) spherical, oval, egg shaped, bean shaped size can vary Found as singles, pairs, irregular clusters, tetrads, cubical packets of 8, etc. 58 29 3/3/2023 Cell Morphology: Cell Shape/Arrangement 2. Bacilli (us) - Elongated cylindrical, rod-like - Vary in diameter, length, shape of ends, arrangement - Arrangement: singles, pairs, chains, parallel packets 59 Cell Morphology: Cell Shape/Arrangement 3. Spirals - Curved rods - Vary in diameter, length, number of curves, tightness of curves, flexibility Three types of spirals a. Vibrios – single curve (comma shaped) b. Spirillum – rigid, two or more curves (cork screw shaped) c. Spirochetes – flexible, two or more curves (wavy, move by flexing bodies) 60 30 3/3/2023 Figure 11.1 Typical prokaryotic morphologies Coccus Spirillum Coccobacillus Spirochete Bacillus Pleomorphic Vibrio 61 FOCUS IN YOUR LAB WORK COLONY MORPHOLOGY – WHAT YOU SEE WITH YOUR NAKED EYE Shape Margin Elevation Size Texture Appearance Pigmentation Optical Property 62 31 3/3/2023 Colony Morphology: Figure 6.8 Characteristics of bacterial colonies. 63 64 32 3/3/2023 BACTERIAL COLONY 65 KEY CONCEPTS PROKARYOTES INTERNAL AND EXTERNAL STRUCTURES in BACTERIAL CELLS – CELL MEMBRANE –MOVEMENT and TRANSPORT CELL MORPHOLOGY vs COLONY MORPHOLOGY 66 33 3/3/2023 UNIT 1 WEEK 2b EUKARYOTIC CELLS Some material taken from 67 Similarities Between Eukaryotic & Prokaryotic Cells 1. Same chemical constituents to build their structural components (lipids, proteins, sugars) 2. Similar biochemical pathways 3. DNA  RNA  protein synthesis (transcription and translation) 4. All have mechanisms for energy production and storage 5. Membrane composition is similar 68 34 3/3/2023 Eukaryotic Cells: An Overview Eukaryotes – – – – – Have nucleus Have internal membrane-bound organelles Are larger (10–100 µm in diameter) Have more complex structure Include algae, protozoa, fungi, animals, and plants © 2012 Pearson Education Inc. 69 Figure 3.3 Typical eukaryotic cell Nuclear envelope Nuclear pore Nucleolus Lysosome Mitochondrion Centriole Secretory vesicle Golgi body Cilium Transport vesicles Ribosomes Rough endoplasmic reticulum Smooth endoplasmic reticulum Cytoplasmic membrane Cytoskeleton 70 35 3/3/2023 71 Types Of Eukaryotic Cells: Protozoa, Fungi & Algae 72 72 36 3/3/2023 Types Of Eukaryotic Cells: Plant & Animal 73 73 Eukaryotic Cell Walls – Fungi, algae, plants, and some protozoa have cell walls – Cell walls are rigid and provide structural support (shape) – Composed of various polysaccharides – Plant cell walls composed of cellulose – Fungal cell walls composed of cellulose, chitin, and/or glucomannan – Algal cell walls composed of a variety of polysaccharides © 2012 Pearson Education Inc. 74 37 3/3/2023 Figure 3.28 A eukaryotic cell wall Cell wall Cytoplasmic membrane 75 External Structure of Eukaryotic Cells Glycocalyces – Animal and MOST protozoan cells lack cell walls but they contain sticky carbohydrate glycocalyces – this is attached to their cytoplasmic membranes – Help anchor animal cells to each other – Strengthen cell surface – Provide protection against dehydration – Function in cell-to-cell recognition and communication – Absent in eukaryotes that possess cell wall! © 2012 Pearson Education Inc. 76 38 3/3/2023 Eukaryotic Cytoplasmic Membranes – Cytoplasm – fluid inside of cell – All eukaryotic cells have cytoplasmic membranes, referred to as a lipid bilayer – A membrane is a fluid mosaic of phospholipids and proteins – Contain steroid (sterols, such as cholesterol) lipids to help maintain fluidity and ensure stability – Contain regions of lipids and proteins called membrane rafts – Control movement into and out of cell  selectively permeable – Eukaryotic cells also contain membrane bound organelles that account for 60-80% of their volume © 2012 Pearson Education Inc. 77 Figure 3.29 Eukaryotic cytoplasmic membrane Cytoplasmic membrane Intercellular matrix Cytoplasmic membrane 78 39 3/3/2023 MOTILITY a. flagella b. cilia c. pseudopods Some material taken from 79 Figure 3.31c Eukaryotic flagella and cilia Cytoplasmic membrane Cytosol Central pair microtubules Microtubules (doublet) “9  2” arrangement Cytoplasmic membrane Portion cut away to show transition area from doublets to triplets and the end of central microtubules Basal body... Microtubules (triplet) “9  0” arrangement 80 40 3/3/2023 Figure 3.31b Eukaryotic flagella and cilia Cilia 81 Figure 3.32 Movement of eukaryotic flagella and cilia-overview Direction of motion Flagella Undulate waves that begin at one end and transverse the length of the flagellum. Direction of motion Cilia Cilia move with a power stroke followed by a return stroke. 82 41 3/3/2023 Eukaryotes Pseudopods – Called false foot – Movement occurs by sending out an extension (pseudopodium) followed by the cytoplasm following toward the extension Function: - Motility and endocytosis © 2012 Pearson Education Inc. 83 Organelles Prokaryotic cells have no organelles Animal and plant cells have many organelles Eukaryotic organelles compartmentalize functions within the cell 84 42 3/3/2023 The Endomembrane System The Endomembrane Membrane – system of internal membranes within eukaryotic cells divide the cell into compartments (organelles) The membranes contain transport systems, for moving molecules through the interior of the cell 85 The Endomembrane System Membranous organelles of the endomembrane system are made of a lipid bilayer: This system consists of: a. Nucleus b. Endoplasmic reticulum c. Golgi apparatus d. Vesicles e. Lysosomes f. Plasma membrane g. Mitochondria h. Vacuoles i. Chloroplasts (plant cells) 86 43 3/3/2023 87 Figure 3.36 Endoplasmic reticulum Membrane-bound ribosomes Mitochondrion Free ribosome Rough endoplasmic Smooth endoplasmic reticulum (SER) reticulum (RER) 88 44 3/3/2023 Figure 3.37 Golgi body Secretory vesicles Vesicles arriving from ER 89 Cisternae cis face Proteins trans face Golgi apparatus Transport vesicle Protein Vesicle Migrating budding transport from rough vesicle endoplasmic reticulum Fusion of vesicle with Golgi apparatus Ribosome 90 45 3/3/2023 Figure 3.38 Vacuole Cell wall Nucleus Central vacuole Cytoplasm 91 Eukaryote Cell: Ribosomes – Ribosomes – Composed of a 60S and 40S subunits – Site of protein synthesis – Found on rough ER or cytoplasm © 2012 Pearson Education Inc. 92 46 3/3/2023 Eukaryote Cell: Mitochondria – Mitochondria – Have two membranes composed of phospholipid bilayer, contain cristae – Produce cell’s ATP – Contains a circular molecule of DNA – rod shaped © 2012 Pearson Education Inc. 93 94 47 3/3/2023 Exocytosis and Endocytosis Exocytosis – cell exports substances Endocytosis – cell imports substances - Substance outside cell binds to plasma membrane, the membrane invaginates, a vesicle forms and allows substance to enter cell 95 Figure 3.39 The roles of vesicles in the destruction of a phagocytized pathogen within a white blood cell Endocytosis (phagocytosis) Bacterium Phagosome (food vesicle) Vesicle fuses with a lysosome Smooth endoplasmic reticulum (SER) Transport vesicle Lysosome Phagolysosome Golgi body Secretory vesicle Exocytosis (elimination, secretion) 96 48 3/3/2023 Figure 3.30 Endocytosis-overview Pseudopodium 97 KEY CONCEPTS SIMILARITIES and DIFFERENCES BETWEEN PROKARYOTIC and EUKARYOTIC CELLS – Important for UNIT 3 98 49