Michael T. Madigan, John M. Martinko, David A. …

1 10/5/2013 1 LECTURE PRESENTATIONS For brock biology OF MICROORGANISMS, THIRTEENTH EDITION Michael T. madigan , john M. martinko , David A. Stahl, David P. Clark Lectures by john Zamora Middle Tennessee State University 2012 Pearson Education, Inc. Cell Structure and Function in Bacteria and Archaea Chapter 3 I. Cell Shape and Size Cell Morphology Cell Size and the Significance of Smallness 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI 10/5/2013 2 Cell Morphology Morphology = cell shape Major cell morphologies (Figure ) Coccus (pl. cocci): spherical or ovoid Rod: cylindrical shape Spirillum: spiral shape Cells with unusual shapes Spirochetes, appendaged bacteria, and filamentous bacteria Many variations on basic morphological types 2012 Pearson Education, Inc.

2 Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI Figure Representative cell morphologies of prokaryotes Coccus Rod Spirillum Spirochete Stalk Hypha Budding and appendaged bacteria Filamentous bacteria 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI Coccus cells may also exist as short chains or grapelike clusters 10/5/2013 3 Cell Morphology Morphology typically does not predict physiology1, ecology, phylogeny2, etc. of a prokaryotic cell Selective forces may be involved in setting the morphology Optimization for nutrient uptake (small cells and those with high surface-to-volume ratio) Swimming motility in viscous environments or near surfaces (helical or spiral-shaped cells) Gliding motility (filamentous bacteria) 2012 Pearson Education, Inc.

3 Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI 1 functions and activities of living organisms and their parts 2 the evolutionary history of a group of organisms Cell Size and the Significance of Smallness Size range for prokaryotes: m to >700 m in diameter Most cultured rod-shaped bacteria are between and m wide and <15 m long Examples of very large prokaryotes Epulopiscium fishelsoni (Figure ) Thiomargarita namibiensis (Figure ) Size range for eukaryotic cells: 10 to >200 m in diameter 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof.

4 BARI ALLI 10/5/2013 4 Figure Some very large prokaryotes 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI Epulopiscium fishelsoniThiomargarita Cell Size and the Significance of Smallness Surface-to-Volume Ratios, Growth Rates, and Evolution Advantages to being small (Figure ) Small cells have more surface area relative to cell volume than large cells ( , higher S/V) support greater nutrient exchange per unit cell volume tend to grow faster than larger cells 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof.

5 BARI ALLI 10/5/2013 5 Figure Surface area and volume relationships in cells r = 1 m r = 2 m r = 1 m r = 2 m Surface area (4 r2) = m2 Volume ( r3) = m3 Surface area = m2 Volume = m3 3 4 Surface Volume = 3 Surface Volume = 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI Cell Size and the Significance of Smallness Lower Limits of Cell Size Cellular organisms < m in diameter are unlikely Open oceans tend to contain small cells ( m in diameter) 2012 Pearson Education, Inc. Marmara University Enve303 Env.

6 Eng. Microbiology Prof. BARI ALLI 10/5/2013 6 II. The Cytoplasmic Membrane and Transport The Cytoplasmic Membrane Functions of the Cytoplasmic Membrane Transport and Transport Systems 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI The Cytoplasmic Membrane in Bacteria and Archaea Cytoplasmic membrane: Thin structure that surrounds the cell 6-8 nm thick Vital barrier that separates cytoplasm from environment Highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products 2012 Pearson Education, Inc.

7 Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI 10/5/2013 7 Composition of Membranes General structure is phospholipid bilayer (Figure ) Contain both hydrophobic and hydrophilic components Can exist in many different chemical forms as a result of variation in the groups attached to the glycerol backbone Fatty acids point inward to form hydrophobic environment; hydrophilic portions remain exposed to external environment or the cytoplasm The Cytoplasmic Membrane Animation: Membrane Structure 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof.

8 BARI ALLI Fatty acids Glycerol Phosphate Ethanolamine Fatty acids Glycerophosphates Hydrophilic region region region Hydrophobic Hydrophilic Fatty acids 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI General architecture of a bilayer membrane; the blue balls depict glycerol with phosphate and (or) other hydrophilic groups. Figure Phospholipid bilayer membrane 10/5/2013 8 The Cytoplasmic Membrane Cytoplasmic Membrane (Figure ) 6-8 nm wide Embedded proteins Stabilized by hydrogen bonds and hydrophobic interactions Mg2+ and Ca2+ help stabilize membrane by forming ionic bonds with negative charges on the phospholipids Somewhat fluid 2012 Pearson Education, Inc.

9 Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI Figure Structure of the cytoplasmic membrane Phospholipids Integral membrane proteins 6 8 nm Hydrophilic groups groups Hydrophobic Out In Phospholipid molecule 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI 10/5/2013 9 The Cytoplasmic Membrane Membrane Proteins Outer surface of cytoplasmic membrane can interact with a variety of proteins that bind substrates or process large molecules for transport Inner surface of cytoplasmic membrane interacts with proteins involved in energy-yielding reactions and other important cellular functions 2012 Pearson Education, Inc.

10 Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI The Cytoplasmic Membrane Membrane Proteins (cont d) Integral membrane proteins Firmly embedded in the membrane Peripheral membrane proteins One portion anchored in the membrane 2012 Pearson Education, Inc. Marmara University Enve303 Env. Eng. Microbiology Prof. BARI ALLI 10/5/2013 10 The Cytoplasmic Membrane Membrane-Strengthening Agents Sterols Rigid, planar lipids found in eukaryotic membranes Strengthen and stabilize membranes Hopanoids Structurally similar to sterols Present in membranes of many Bacteria 2012 Pearson Education, Inc.