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Anatomy and Physiology of Prokaryotic Cells Microbiology Mrs. Hieneman.

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Presentation on theme: "Anatomy and Physiology of Prokaryotic Cells Microbiology Mrs. Hieneman."— Presentation transcript:

1 Anatomy and Physiology of Prokaryotic Cells Microbiology Mrs. Hieneman

2 Bacterial Shape and Arrangement

3 Streptococcus chain

4 Sarcinae cube

5 Staphylococcus aureus cluster

6 Spiral-shaped bacterial cell

7 Prokaryotic Cell Structure

8 Cytoplasmic Membrane Surrounds cytoplasm and defines boundaries of cell Acts as barrier, but also functions as an effective and highly discriminating conduit between cell and surroundings Made up of phospholipid bilayer

9 Figure 4.14c

10 Phospholipid

11 Figure 4.14b

12 Movement of Molecules through Cytoplasmic Membrane Several ways for molecules to move through membrane 1.Simple Diffusion 2.Osmosis 3.Facilitated Diffusion 4.Active Transport

13 Simple Diffusion Does not require expenditure of energy Process by which some molecules move freely into and out of the cell Small molecules such as carbon dioxide and oxygen

14 Microbiology: An Introduction, 9e by Tortora, Funke, Case Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.18: The principle of osmosis - Overview. (a) At beginning of osmotic pressure experiment (b) At equilibrium (c) Isotonic solution — no net movement of water (d) Hypotonic solution — water moves into the cell and may cause the cell to burst if the wall is weak or damaged (osmotic lysis) (e) Hypertonic solution — water moves out of the cell, causing its cytoplasm to shrink (plasmolysis) Glass tube Rubber stopper Rubber band Sucrose molecule Water molecule Cellophane sack Cytoplasm SolutePlasma membrane Cell wall Water

15 Transport Proteins Transport proteins (or transporters) responsible for: Facilitated Diffusion Active Transport

16 Microbiology: An Introduction, 9e by Tortora, Funke, Case Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.17: Facilitated diffusion. Transported substance Transporter protein Outside Inside Glucose Plasma membrane

17 Cell Wall Composed of peptidoglycan Comprised of alternating NAG and NAM molecules Attached to each NAM is four amino acid peptide: tetrapeptide


19 Categories of Bacteria Two Major Categories: Difference due to difference in chemical structures of their cell walls –Gram positive: stains purple –Gram negative: stains red

20 Gram + Cell Wall Thick Layer of Peptidoglycan Contains techoic acid: chains of ribitol- phosphate or glycerol-phosphate to which sugars or alanine attached Techoic Acid sticks out above the peptidoglycan layer



23 Gram – Cell Wall More complex than Gram + cell wall Thin layer of peptidoglycan –Sandwiched between the cytoplasmic membrane and outer membrane Outside of peptidoglycan is outer membrane

24 Figure 4.13c

25 Outer Membrane Unlike any other membrane in nature A lipid bilayer with the outside layer made of lipopolysaccharides instead of phospholipids Also called LPS Contains Porins


27 Periplasm - Region between cytoplasmic membrane and the outer membrane - Gel-like fluid Filled with secreted proteins and enzymes

28 External Structures Glycocallyx Flagella Axial Filaments Fimbrae and Pili

29 Glycocallyx Gel-like structure –Functions in protection and attachment –Two types- capsule and slime layer –Involved in attachment, enabling bacteria to stick to teeth, rocks –Enables bacteria to brow as biofilm

30 Capsule in Acinetobacter species by gram negative staining

31 Filamentous Protein Appendages Anchored in membrane and protrude from surface Flagella: long structure responsible for motility Fimbrae and Pili: shorter, responsible for attachment

32 Four types of bacteria with flagella Montrichious- one flagella Amphitrichous- flagella at both ends Lophitrichous- many flagella at the end of the cell Peritrichous- flagella all over entire cell

33 Figure 4.7 - Overview

34 Axial Filament Present in Spirochetes Attach at end of cell, spiral around, underneath an outer sheath Move like a corkscrew

35 Figure 4.10 - Overview

36 Fimbrae and Pili Shorter and surround the cell Similar structural theme to filament of flagella Fimbrae- enable cell to adhere to surfaces, including other cells Pili- join bacterial cells in preparation for the transfer of DNA from one cell to another


38 Internal Structures of Prokaryotic Cells

39 Cytoplasm Substance of cell inside the cytoplasmic membrane About 80% water Thick, aqueous, semitransparent, elastic

40 Chromosome Found within a central location known as nucleoid Single, circular, double stranded Consists of all DNA required by cell


42 Plasmids Some bacteria contain plasmids- small circular double-stranded DNA Typically cell does not require genetic information carried on plasmid However, it may be advantageous

43 Ribosomes Site of protein synthesis Relative size and density of ribosomes and their subunits expressed as distinct unit (S) Two units of prokaryotic ribosomes: 50S + 30S= 70S Eukaryotic ribosomes: 80S

44 Microbiology: An Introduction, 9e by Tortora, Funke, Case Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.19: The prokaryotic ribosome. (a) Small subunit(b) Large subunit(c) 50S 30S (c) Complete 70S ribosome

45 Inclusions Store excess nutrients Examples: Polysaccharide granules- glycogen and starch Lipid inclusions Metachromatic granules- inorganic phosphate that can be used to synthesize ATP


47 Endospores Occurs in members of genera Bacillus and Clostridium Dormant cell produced by a process called Sporulation Germination- when they exit the dormant state and then become a vegetative cell Several species of endospore formers can cause disease



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