Chapter 4 M I C R O B I O L O G Y. The Anatomy of the Cell. a n i n t r o d u c t i o n

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1 ninth edition TORTORA FUNKE CASE M I C R O B I O L O G Y a n i n t r o d u c t i o n Chapter 4 The Anatomy of the Cell PowerPoint Lecture Slide Presentation prepared by Christine L. Case! Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

2 Comparing Prokaryotic and Eukaryotic Cells Prokaryotes and eukaryotes chemically similar Composed of carbohydrates, proteins, nucleic acids, lipids Perform same kinds of chemical reactions Differences are primarily in internal, external structures Prokaryotic Cell Eukaryotic Cell

3 Comparing Prokaryotic and Eukaryotic Cells Prokaryotes One circular chromosome, not in a nuclear membrane No histones with DNA No organelles Peptidoglycan cell walls Simple cell division binary fission Eukaryotes Linear chromosomes, in a nuclear membrane Histones with DNA Organelles Polysaccharide cell walls Complex cell division - mitosis

4 The Size, Shape, and Arrangement of Bacterial Cells Bacteria come in many shapes and sizes Average size: µm diameter, 2-8 µm long Three basic shapes:! Coccus (plural cocci) spherical, round! Bacillus (pl bacilli) - rod-shaped, oval! Spiral spiral shaped, twisted! Other less common shapes exist!

5 The Size, Shape, and Arrangement of Bacterial Cells Coccus, cocci Usually round, can be oval, elongated, or flattened

6 The Size, Shape, and Arrangement of Bacterial Cells Bacillus, bacilli Rod-shaped, oval shaped

7 The Size, Shape, and Arrangement of Bacterial Cells Spiral Have one or more twists Three types: Vibrio curved rods Spirilla corkscrew shape, rigid Spirochetes helical, flexible

8 The Size, Shape, and Arrangement of Bacterial Cells Unusual shapes Star-shaped, eg Stella Square, eg Haloarcula

9 The Size, Shape, and Arrangement of Bacterial Cells Genetics determines bacterial shape Monomorphic always maintains single shape Helps in identifying bacteria Pleomorphic can have several shapes Often due to environment More difficult to identify

10 Structures External to the Cell Wall Glycocalyx - A sugar coat on surface of bacteria Gelatinous polymer of polysaccharides, polypeptides external to cell wall Made inside cell, secreted to outside Glycocalyx Cell wall

11 Structures External to the Cell Wall Two general types of glycocalyx Capsule organized, firmly attached Slime layer unorganized, loosely attached Capsules can be important in contributing to virulence Only encapsulated B. anthracis causes anthrax Protects bacteria from immune system, dehydration Capsules made of sugars called extracellular polysaccharide (EPS) Allows bacteria to attach to various surfaces S. mutans EPS attaches to teeth, causes tooth decay

12 Structures External to the Cell Wall Flagella long appendages that move bacteria Flagella (a flagellum) give bacteria motility Ability to move by itself Three basic parts to a flagellum Filament Hook Basal body Four arrangements of flagella

13 Structures External to the Cell Wall Structure of a Flagellum Filament long outermost region, hollow Hook bridges filament to cell wall Basal Body anchors flagellum to cell, acts as motor

14 Structures External to the Cell Wall Monotrichous one single flagellum No Flagella = Atrichous Amphitrichous one at each end Lophotrichous two or more at one or both ends Peritrichous all over entire cell

15 Structures External to the Cell Wall Taxis movement towards or away from environment Positive taxis towards environment Environment called attractant Negative taxis away from environment Environment called repellant Environment includes chemicals, light Movement towards light positive phototaxis Movement away from chemical negative chemotaxis

16 Structures External to the Cell Wall Axial filaments bundles of fibers that spiral around cell! Found uniquely in spirochetes! Rotation cause cell to move in spiral motion

17 Structures External to the Cell Wall Fimbriae and Pili! Short, hairlike appendages, not used for motility! Fimbriae! Used to stick to surfaces! N. gonorrhoeae sticks via fimbriae! No fimbriae, no disease!

18 Structures External to the Cell Wall Pili, pilus Used to transfer DNA between bacteria Process called conjugation Pilus

19 Which cell(s) has a coccus shape? 1. A 2. B 3. C 0% 0% 0% 1 2 3

20 How would you describe the flagellar arrangement? 1. Lophotrichous 2. Monotrichous 3. Amphitrichous 4. Peritrichous 0% 0% 0% 0%

21 Which cell(s) contain axial filaments? 1. A 2. B 3. C 4. D 5. E 0% 0% 0% 0% 0%

22 Which of the following cell structures has a role in the initiation of disease? 1. Cell membrane 2. Fimbriae 3. Flagella 4. Cell wall 0% 0% 0% 0%

23 The Cell Wall The cell wall surrounds the cell membrane and protects the cell, provides shape of cell! Bacterial cell wall made of peptidoglycan Cell wall Cell membrane

24 The Cell Wall Peptidoglycan is polymer of disaccharide NAG and NAM; forms carbohydrate backbone Linked by short chains of amino acids (polypeptides)

25 The Cell Wall Arrangement of Bacterial cell wall used to classify into 2 groups Gram-positive bacteria Gram-negative bacteria

26 The Cell Wall Gram-positive cell wall Thick, many layers of peptidoglycan Contains teichoic acid

27 The Cell Wall Teichoic acids; negatively charged Lipoteichoic acid links to plasma membrane Wall teichoic acid links to peptidoglycan

28 The Cell Wall Gram-negative cell wall Thin layer of peptidoglycan between two membranes In periplasm between outer and plasma membranes

29 The Cell Wall Outer membrane contains lipopolysaccharides (LPS), lipoproteins, phospholipids The outer membrane protects the cell from immune system, antibiotics Porins (proteins) form channels through outer membrane Allows nutrients into cell

30 The Cell Wall Gram-Positive Gram-Negative Cell Walls Cell Walls Thick peptidoglycan Teichoic acids Thin peptidoglycan in periplasm Outer membrane with LPS

31 The Cell Wall Atypical cell walls Acid-fast cell walls Contain layer of mycolic acid, a waxy lipid, outside of peptidoglycan layer Found in Mycobacterium, Nocardia

32 The Cell Wall Atypical cell walls Archaea Lack peptidoglycan No cell wall, or walls typically of pseudomurein! Mycoplasmas Smallest known bacteria Lack cell walls Sterols in plasma membrane, provide strength

33 If you isolate teichoic acid from the cell wall of an unknown microbe, you know that. 1. you have isolated a eukaryotic cell 2. you have isolated gramnegative bacterium 3. the cell wall is composed of cellulose 4. you have isolated a grampositive bacterium you have isola... 0% 0% 0% 0% you have isola... the cell wall... you have isola...

34 In a gram-negative cell, the peptidoglycan layer exists. 1. in the periplasm 2. underneath the plasma membrane 3. on top of the outer membrane 4. anchored by teichoic acid in the peripla... 0% 0% 0% 0% underneath the... on top of the... anchored by te...

35 Which type of cell contains endotoxins? 1. Gram-positive cells 2. Gram-negative cells 3. Acid-fast cells 0% 0% 0% 1 2 3

36 Plasma Membrane Thin layer, encloses interior of cell Plasma membrane

37 Plasma Membrane Consists primarily of phospholipids Arranged in two parallel rows called lipid bilayer Hydrophilic heads on two external surfaces of membrane Hydrophobic tails in interior of membrane Outside of cell Hydrophilic heads Hydrophobic tails The lipid bilayer Inside of cell Hydrophilic heads

38 Plasma Membrane Proteins within membrane perform various functions Channels, structure transport Phospholipids and proteins not static Constantly in motion Referred to as Fluid Mosaic Model Transport Structure

39 Plasma Membrane Selective barrier for materials into and out of cell Selective permeability only certain molecules can pass barrier Large molecules cannot pass too big to squeeze through Ions cannot pass charges on phospholipids repel Hydrophobic molecules (oxygen, carbon dioxide) can pass core of membrane is hydrophobic Transport proteins allow specific molecules to pass

40 The Movement of Materials Across Membranes Recall: the plasma membrane is selectively permeable Allows only some materials to cross In order to generate energy, food must cross membrane Most resources too large to cross membrane

41 The Movement of Materials Across Membranes Molecules move across membranes through two general processes Passive processes molecules move from an area of higher concentration to area of lower concentration (down the concentration gradient) Requires no energy Active processes molecules move from an area of lower concentration to area of higher concentration (up the concentration gradient) Requires energy

42 The Movement of Materials Across Membranes Passive processes (3 mechanisms) Simple diffusion Net overall movement of molecules from an area of higher concentration to area of lower concentration Equilibrium the point when molecules are evenly distributed Simple diffusion across plasma membrane important for small molecules like oxygen, carbon dioxide

43 Diffusion

44 The Movement of Materials Across Membranes Facilitated diffusion Similar to diffusion, ie down the concentration gradient Uses transporter proteins to cross membrane Molecules cannot cross membrane unaided Glucose is too large to diffuse across membrane via simple diffusion

45 Simple vs Facilitated Diffusion

46 The Movement of Materials Across Membranes Active Processes (1 Mechanism) Active Transport Sometimes cell needs to move molecules up the concentration gradient Cell uses energy Requires transporter proteins in membrane

47 Active Transport

48 The Movement of Materials Across Membranes Osmosis: The movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water concentration Osmotic pressure: The pressure needed to stop the movement of water across the membrane.

49 The Movement of Materials Across Membranes Tonicity measure of solute concentration in a solution relative to membrane Isotonic solution solute concentration of a solution is equal to solute concentration in cell (iso means equal) Solute inside = solute outside Water inside = water outside No net movement of water across membrane

50 The Movement of Materials Across Membranes Hypotonic solution solute concentration of a solution is lower than solute concentration in cell (hypo means less, under) Solute inside > solute outside Water inside < water outside Net movement of water is from outside to inside Cells swell, can burst osmotic lysis Cell wall protects against osmotic lysis

51 The Movement of Materials Across Membranes Hypertonic solution solute concentration of a solution is higher than solute concentration in cell (hyper means more, above) Solute inside < solute outside Water inside > water outside Net movement of water from inside to outside Cell shrink, collapse - plasmolysis

52 Osmosis

53 List the similarities and differences of: 1. Simple diffusion vs facilitated diffusion 2. Facilitated diffusion vs active transport 3. Simple diffusion vs osmosis

54 Which of these molecules can cross the membrane? 1. Fructose, a monosaccharide. 2. Hydrogen gas, a small hydrophobic gas. 3. A sodium ion, important for muscle contractions. 4. Penicillin, an antibiotic protein. 0% 0% 0% 0%

55 What is the similarity between facilitated diffusion and active transport? 1. Both require energy. 2. Both require transport proteins. 3. Both move molecules down the concentration gradient. 4. Both move molecules up the concentration gradient. 0% 0% 0% 0%

56 Nitrate, NO 3-, is an important nutrient for many bacteria. By which mechanism would a bacterium transport nitrate into the cell? 1. Simple diffusion 2. Facilitated diffusion 3. Osmosis 0% 0% 0% 1 2 3

57 What will happen if a bacterial cell is placed in 10% NaCl (hypertonic)? 1. The cell will undergo plasmolysis. 2. The cell will undergo osmotic lysis. 3. Active transport will be activated. 4. NaCl will rush into the cell. 0% 0% 0% 0%

58 Cytoplasm The Cytoplasm is the substance inside the plasma membrane Contains:! About 80% water, proteins, carbohydrates, lipids, inorganic ions! Protein filaments help maintain shape of some bacteria

59 The Nuclear Area Sometimes called nucleoid Contains DNA molecule called chromosome! Bacteria can also contain plasmids - which are small circular DNA molecules! Often carry useful genes, ie antibiotic resistance! Can be shared between bacteria Nucleoid with bacterial chromosome

60 The Nuclear Area Ribosomes Responsible for protein synthesis Composed of proteins and ribosomal RNA (rrna) Bacterial ribosomes (70S) consist of two subunits Small subunit, 30S subunit Large subunit, 50S subunit S refers to size Bacterial ribosome

61 Inclusions Inclusions are reserve deposits found within cytoplasm! Can store nutrients, provide various functions

62 The Nuclear Area Type of inclusion Metachromatic granules (volutin) Polysaccharide granules Lipid inclusions Sulfur granules Carboxysomes Gas vacuoles Magnetosomes Function Phosphate reserves Energy reserves Energy reserves Energy reserves Ribulose 1,5-diphosphate carboxylase for CO 2 fixation Protein covered cylinders Iron oxide (destroys H 2 O 2 )

63 Endospores They are resting structures formed by some bacteria such as Bacillus, Clostridium Resistant to desiccation, heat, chemicals Sporulation: Endospore formation Germination: Return to vegetative state

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66 Extra Credit Available Nov 5 (Saturday) from 8-4 Develop hands-on activities for children I have them, just need them beta-tested Build some sort of display or something to make the booth exciting-ish Science principles behind activities must be displayed and/or explained On top of extra credit (small-ish), service hours Good for potential scholarship, resume

67 BUILD A BACTERIUM

68 Build a Bacterium Given the following scenarios which describe what traits or activities are needed, build your bacterium List the structure(s) that will help your bacterium accomplish its goals

69 Although you intend to make your living in a human for many years to come, some say you re a bit stiff, like a statue in a wax museum.

70 You finally feel ready to settle down in one spot for good this time. But first you ve got to find your way to the right spot.

71 You re a bit of a swinger you re looking to swap genes with someone, preferably someone who can resist the effects of that newest antibiotic on the market.

72 You re kind of an outdoorsy type of microbe but it can be quite hostile out there. Why don t you just hang out outdoors? You re in no hurry to annoy those big humans anyway.

73 You re sneaky and would like to avoid the deadly grip of white blood cell phagocytes. Plus, you ve got a sweet tooth.

74 It made you happy to live in your human host, once you found your way to a good spot. Of course, they re not happy having you in them, but if they kill you, they re in for a nasty surprise! Revenge of the killer microbes!

75 The Eukaryotic Cell Typically larger, more structurally complex than prokaryotic cells Eukaryotic cells about 10 to 100 µm in diameter Prokaryotic Cell Eukaryotic Cell

76 The Plasma (Cytoplasmic) Membrane Similar to prokaryotic membrane Composed of a phospholipid bilayer Includes proteins embedded in the bilayer Eukaryotic plasma membrane contains carbohydrates and sterols! Not found in prokaryotic cells (exception: Sterols are found in which prokaryote?)

77 The cell wall and glycocalyx Cell wall is generally simpler than prokaryotic cell wall Polysaccharides, not peptidoglycan Plants, algae have cellulose cell wall Fungi have chitin cell wall Many eukaryotes have no cell walls Some eukaryotes have glycocalyx Help strengthen cell surface, attach cells together

78 Cytoplasm Cytoplasm: Everything inside the plasma membrane and outside nucleus Cytosol: Fluid portion of cytoplasm Major differences compared to prokaryotic cells Presence of cytoskeleton Provides support, shape, movement Specialized enzymes (ie for metabolism) are found in organelles

79 Organelles Structures with specialized functions Not found in prokaryotic cells Nucleus: Storage of DNA Endoplasmic Reticulum (ER): Synthesis of molecules Golgi complex: Transport of molecules Lysosome: Degradation & recycling of molecules Vacuole: Storage of molecules Mitochondrion: ATP generation Chloroplast: Photosynthesis Peroxisome: Degradation of toxins