Functional Anatomy of Prokaryotic and Eukaryotic Cells Chapter 4 Functional Anatomy of Prokaryotic and Eukaryotic Cells Lectures prepared by Christine L. Case © 2013 Pearson Education, Inc. 1

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Prokaryotic and Eukaryotic Cells Prokaryote comes from the Greek words for prenucleus. Eukaryote comes from the Greek words for true nucleus.

One circular chromosome, not in a membrane Prokaryote Eukaryote One circular chromosome, not in a membrane No organelles Bacteria: peptidoglycan cell walls Archaea: pseudomurein cell walls Binary fission Paired chromosomes, in nuclear membrane Organelles Polysaccharide cell walls Mitotic spindle

Prokaryotic Cells: Shapes Average size: 0.2–1.0 µm  2–8 µm Most bacteria are monomorphic A few are pleomorphic

Figure 4.9b Flagella and bacterial motility. A Proteus cell in the swarming stage may have more than 1000 peritrichous flagella.

Basic Shapes Bacillus (rod-shaped) Coccus (spherical or circular) Spiral Spirillum Vibrio Spirochete

Plane of division Diplococci Streptococci Figure 4.1a Arrangements of cocci. Plane of division Diplococci Streptococci

Figure 4.2ad Bacilli. Single bacillus Coccobacillus

Figure 4.4 Spiral bacteria. Vibrio Spirillum Spirochete

Bacillus or Bacillus Scientific name: Bacillus Shape: bacillus

Figure 4.5a Star-shaped and rectangular prokaryotes. Star-shaped bacteria

Figure 4.5b Star-shaped and rectangular prokaryotes. Rectangular bacteria

Arrangements Pairs: diplococci, diplobacilli Clusters: staphylococci Chains: streptococci, streptobacilli

Plane of division Diplococci Streptococci Staphylococci Figure 4.1ad Arrangements of cocci. Plane of division Diplococci Streptococci Staphylococci

Figure 4.2b-c Bacilli. Streptobacilli Diplobacilli

Figure 4.6 The Structure of a Prokaryotic Cell. The drawing below and the micrograph at right show a bacterium sectioned lengthwise to reveal the internal composition. Not all bacteria have all the structures shown; only structures labeled in red are found in all bacteria. Cell wall Capsule Although the nucleoid appears split in the photomicrograph, the thinness of the “slice” does not convey theobject’s depth. Pilus Cytoplasm 70S Ribosomes Plasma membrane Nucleoid containing DNA Inclusions Plasmid Fimbriae Capsule Cell wall Plasma membrane Flagella © 2013 Pearson Education, Inc. .

Glycocalyx Outside cell wall Usually sticky Capsule: neatly organized Capsules prevent phagocytosis Hard to get rid of Slime layer: unorganized and loose Can be rinsed off with disinfectants Extracellular polysaccharide allows cell to attach Important component of biofilms

Figure 24.12 Streptococcus pneumoniae, the cause of pneumococcal pneumonia.

Flagella Outside cell wall Made of chains of flagellin Attached to a protein hook Anchored to the wall and membrane by the basal body Rotate flagella to run or tumble Move toward or away from stimuli (taxis)

Parts and attachment of a flagellum of a gram-positive bacterium Figure 4.8b The structure of a prokaryotic flagellum. Flagellum Gram- positive Filament Cell wall Hook Basal body Peptidoglycan Plasma membrane Cytoplasm Parts and attachment of a flagellum of a gram-positive bacterium

Parts and attachment of a flagellum of a gram-negative bacterium Figure 4.8a The structure of a prokaryotic flagellum. Flagellum Filament Gram- negative Cell wall Hook Basal body Peptidoglycan Outer membrane Plasma membrane Cytoplasm Parts and attachment of a flagellum of a gram-negative bacterium

Run Tumble Run Tumble Run Tumble Figure 4.9a Flagella and bacterial motility. Run Tumble Run Tumble Run Tumble A bacterium running and tumbling. Notice that the direction of flagellar rotation (blue arrows) determines which of these movements occurs. Gray arrows indicate direction of movement of the microbe.

Figure 4.7 Arrangements of bacterial flagella. Peritrichous Monotrichous and polar Lophotrichous and polar Amphitrichous and polar

Axial Filaments Also called endoflagella In spirochetes Anchored at one end of a cell Rotation causes cell to move

Figure 4.10b Axial filaments. Outer sheath Cell wall Axial filament A diagram of axial filaments wrapping around part of a spirochete (see Figure 11.26a for a cross section of axial filaments)

Fimbriae and Pili Found on many gram NEGATIVE bacteria Short, thin, hairlike appendages 2 Types: Fimbriae Allow attachment which usually leads to infection Different numbers Pili Facilitate transfer of DNA from one cell to another Motility 1-2 per cell

Figure 4.11 Fimbriae. Fimbriae

The Cell Wall Prevents osmotic lysis Made of peptidoglycan (in bacteria) CELL WALL

Differences in Cell Walls GRAM POSITIVE GRAM NEGATIVE Thick peptidoglycan Teichoic acids May regulate movement of cations Penicillin sensitive Thin peptidoglycan Outer membrane Lipopolysaccharides Protection from phagocytes, complement, and antibiotics Tetracycline Sensitive

Figure 4.13b-c Bacterial cell walls. Peptidoglycan Wall teichoic acid Lipoteichoic acid Cell wall Plasma membrane Protein O polysaccharide Gram-positive cell wall Core polysaccharide Core polysaccharide Lipid A Lipopolysaccharide O polysaccharide Parts of the LPS Lipid A Porin protein Lipoprotein Outer membrane Phospholipid Cell wall Peptidoglycan Plasma membrane Periplasm Protein Gram-negative cell wall

The Gram Stain Mechanism Crystal violet-iodine crystals form in cell Gram-positive Alcohol dehydrates peptidoglycan CV-I crystals do not leave Gram-negative Alcohol dissolves outer membrane and leaves holes in peptidoglycan CV-I washes out

Table 4.1 Some Comparative Characteristics of Gram-Positive and Gram-Negative Bacteria

Atypical Cell Walls Acid-fast cell walls Like gram-positive cell walls Waxy lipid (mycolic acid) bound to peptidoglycan 2 Genera: Mycobacterium Nocardia

Figure 24.8 Mycobacterium tuberculosis.

Atypical Cell Walls Mycoplasmas Archaea Lack cell walls Sterols in plasma membrane Archaea Wall-less Walls without peptidoglycan

Damage to the Cell Wall Lysozyme- enzyme that digests peptidoglycan Penicillin- inhibits peptide bridges in peptidoglycan Protoplast- wall-less cell gram-positive cell Spheroplast- wall-less gram-negative cell Protoplasts and spheroplasts are susceptible to osmotic lysis L forms-wall-less cells that swell into irregular shapes

Plasma membrane of cell Figure 4.14a Plasma membrane. Lipid bilayer of plasma membrane Peptidoglycan Outer membrane Plasma membrane of cell

The Plasma Membrane Selectively permeable Produce ATP Damage to the membrane by alcohols, ammonium (detergents), and polymyxin antibiotics causes leakage of cell contents Phospholipid bilayer Proteins: Peripheral proteins- inner or outer surface Act as enzymes Support Changes in shape during movement Integral proteins (transmembrane)-penetrate membrane completely Channels or pores through which substance leave and enter the cell

Lipid bilayer of plasma membrane Figure 4.14b Plasma membrane. Outside Lipid bilayer Pore Peripheral protein Inside Polar head Integral proteins Nonpolar fatty acid tails Peripheral protein Polar head Lipid bilayer of plasma membrane

Movement of Materials across Membranes Simple diffusion: movement of a solute from an area of high concentration to an area of low concentration

Movement of Materials across Membranes Facilitated diffusion: solute combines with a transporter protein in the membrane

Movement of Materials across Membranes Osmosis: the movement of water across a selectively permeable membrane from an area of high water to an area of lower water concentration

Movement of Materials across Membranes Through lipid layer Aquaporins (water channels)

Figure 4.18c-e The principle of osmosis. Plasma membrane Cytoplasm Solute Water Isotonic solution. No net movement of water occurs. Hypotonic solution. Water moves into the cell. If the cell wall is strong, it contains the swelling. If the cell wall is weak or damaged, the cell bursts (osmotic lysis). Hypertonic solution. Water moves out of the cell, causing its cytoplasm to shrink (plasmolysis).

Movement of Materials across Membranes Active transport: requires a transporter protein and ATP Group translocation: requires a transporter protein and the substance going across the protein is CHEMICALLY changed

Cytoplasm The substance inside the plasma membrane Contains 80% water Contains major structures of the cell

Genetic Information Bacterial chromosome- genetic information for the cell’s structure and function;usually circular Plasmid- extrachromosomal genetic information; may carry genes for antibiotic resistance, tolerance to metals, toxin production

The Prokaryotic Ribosome Protein synthesis 70S 50S + 30S subunits

Inclusions Reserve deposits Store nutrients to have in times of need.

Endospores Resting cells Resistant to desiccation, heat, chemicals Bacillus, Clostridium Sporulation: endospore formation Germination: return to vegetative state

An endospore of Bacillus subtilis Figure 4.21b Formation of endospores by sporulation. Endospore An endospore of Bacillus subtilis

Figure 4.21a Formation of endospores by sporulation. Cell wall Cytoplasm Spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm. Plasma membrane starts to surround DNA, cytoplasm, and membrane isolated in step 1. Plasma membrane Bacterial chromosome (DNA) Sporulation, the process of endospore formation Spore septum surrounds isolated portion, forming forespore. Two membranes Peptidoglycan layer forms between membranes. Spore coat forms. Endospore is freed from cell.

Figure 4.22a Eukaryotic cells showing typical structures. PLANT CELL ANIMAL CELL Peroxisome Flagellum Nucleus Mitochondrion Microfilament Nucleolus Golgi complex Golgi complex Microtubule Basal body Vacuole Cytoplasm Chloroplast Microfilament Ribosome Lysosome Cytoplasm Centrosome: Centriole Pericentriolar material Smooth endoplasmic reticulum Cell wall Ribosome Microtubule Peroxisome Rough endoplasmic reticulum Nucleus Nucleolus Mitochondrion Smooth endoplasmic reticulum Plasma membrane Highly schematic diagram of a composite eukaryotic cell, half plant and half animal Plasma membrane

Figure 4.23a-b Eukaryotic flagella and cilia. Flagellum Cilia A micrograph of Euglena, a chlorophyll- containing alga, with its flagellum. A micrograph of Tetrahymena, a common freshwater protozoan, with cilia.

Flagella and Cilia Microtubules- long hollow tubes 9 pairs + 2 arrangement Flagella- move in a wavelike manner.

The Cell Wall and Glycocalyx Plants, algae, fungi Cellulose (Plants) Chitin (Fungi) Glucan and Mannan (Yeasts) Glycocalyx Carbohydrates extending from plasma membrane Strengthens cell surface, attachment of cells together, cell-cell recognition

The Plasma Membrane Phospholipid bilayer Peripheral proteins Integral proteins Transmembrane proteins Sterols- important in cells without cell wall because it offers stability to the cell Glycocalyx carbohydrates

The Plasma Membrane Selective permeability allows passage of some molecules Simple diffusion Facilitative diffusion Osmosis Active transport Endocytosis Phagocytosis: pseudopods extend and engulf particles Pinocytosis: membrane folds inward, bringing in fluid and dissolved substances

Table 4.2 Principal Differences between Prokaryotic and Eukaryotic Cells

Cytoplasm Cytosol: fluid portion of cytoplasm Cytoskeleton: microfilaments, intermediate filaments, microtubules Provides support and shape and assists in transportation of substances. Cytoplasmic streaming: movement of cytoplasm throughout cells

Ribosomes Protein synthesis 80S 70S Membrane-bound: attached to ER Free: in cytoplasm 70S In chloroplasts and mitochondria

Organelles Nucleus: contains chromosomes Lysosome: digestive enzymes The control center Most prominent internal organelle. Composed of: Nuclear envelope- 2 parallel membranes that are separated by a space; also has small pores on the surface Nucleoplasm- inside space of the nucleus Nucleolus- granular mass; RNA synthesis and ribosomal subunit collection area Lysosome: digestive enzymes Vacuole: brings food into cells and provides support

Nuclear pore(s) Nuclear envelope Nucleolus Chromatin Figure 4.24c The eukaryotic nucleus. Nuclear pore(s) Nuclear envelope Nucleolus Chromatin

Endoplasmic Reticulum Microscopic tunnel system made of cisternae Functions: Storage Transportation 2 types: Rough endoplasmic reticulum (RER)- continuous with the nuclear envelope; has ribosomes on surface; transports materials from nucleus to the cytoplasm and is responsible for protein synthesis. Smooth endoplasmic reticulum (SER)- continuous with RER; no ribosomes; is responsible for nutrient processing and synthesis and storage of lipids, electrolytes, and other substances.

Nuclear envelope Ribosomes Cisternae Smooth ER Ribosomes Rough ER Figure 4.25 Rough endoplasmic reticulum and ribosomes. Nuclear envelope Ribosomes Cisternae Smooth ER Ribosomes Rough ER

Golgi Complex Modify and secrete proteins 3 types of vesicles: Transitional- membrane bound packets of proteins that come to the Golgi from the ER for modification. Condensing- membrane bound packets of proteins that pinch off from the Golgi and are used by organelles on the inside of the cell Secretory-membrane bound packets of proteins that pinch off from the Golgi and are transported outside of the cell

Figure 4.26 Golgi complex. Secretory vesicles Transfer vesicles Cisternae Transport vesicle from rough ER

Lysosomes Contain digestive enzymes capable of breaking down substances Vacuoles Temporary storage units Help to bring food into cell Take in water

Transmission electron micrographs of plant and animal cells. Figure 4.22b Eukaryotic cells showing typical structures. Animal cell, an antibody-secreting plasma cell Peroxisome Nucleus Vacuole Chloroplast Plasma membrane Golgi complex Nucleus Mitochondrion Cytoplasm Nucleolus Cell wall Algal cell (Tribonema vulgare) Mitochondrion Rough endoplasmic reticulum Lysosome Transmission electron micrographs of plant and animal cells.

Mitochondria “Powerhouse” of the cell Supplies most of the energy for the cell Number varies Carries out cellular respiration and produces ATP.

Chloroplasts Algae Helps with photosynthesis

Peroxisomes Similar to lysosomes. Store enzymes Catalase- breaks down hydrogen peroxide (H2O2)

Centrosome Composed of protein fibers and centrioles Plays critical role in cellular division Makes microtubles

Figure 10.2 A model of the origin of eukaryotes.

Endosymbiotic Theory What are the fine extensions on the protozoan shown on the following slide? Larger bacteria engulfed smaller bacteria. Their relationship became symbiotic.