CHAPTER 3

• Process of Life

  • Growth • Reproduction • Responsiveness • Metabolism
• • Include bacteria and archaea

  • Have a simple structure

  • Lack nucleus

  • Lack various membrane-bound internal structures

  • Are typically 1.0 µm in diameter or smaller

  Prokaryotes
• • Have nucleus • Have internal membrane-bound organelles • Are typically 10–100 µm in diameter • Have more complex structure • Include algae, protozoa, fungi, animals, and plants


  Eukaryotes
• • Gelatinous, sticky substance surrounding the outside of the cell • Composed of polysaccharides, polypeptides, or both


  Glycocalyx
• • Composed of organized repeating units of organic chemicals • Firmly attached to cell surface • May prevent bacteria from being recognized by host


  Capsule
• • Loosely attached to cell surface • Water soluble • Sticky layer allows prokaryotes to attach to surfaces as biofilms


  Slime layer
• Two types of glycocalyx

  • Capsule

  • Slime layer
• • Are responsible for movement • Have long structures that extend beyond cell surface • Are not present on all bacteria


  Flagella
• Flagella Function

  • Rotation propels bacterium through environment • Rotation reversible; can be counterclockwise or clockwise • Bacteria move in response to stimuli (taxis) • Runs • Tumbles
• • Sticky, bristlelike projections • Used by bacteria to adhere to one another and to substances in environment • Shorter than flagella • Serve an important function in biofilms


  Fimbriae
• • Special type of fimbria • Also known as conjugation pili • Longer than fimbriae but shorter than flagella • Bacteria typically have only one or two per cell • Transfer DNA from one cell to another (conjugation)


  Pili
• Has relatively thick layer of peptidoglycan

  Gram-positive bacterial cell wall
• Gram-positive bacterial cell wall contain unique polyalcohols called teichoic acids
• Gram-positive bacterial cell wall appear purple following Gram staining procedure
• Have only a thin layer of peptidoglycan

  Gram-Negative Bacterial Cell Walls
• Gram-Negative Bacterial Cell Walls bilayer membrane outside the peptidoglycan contains
• Gram-Negative Bacterial Cell Walls appear pink following Gram staining procedure
• A few bacteria lack cell walls
• • Liquid portion of cytoplasm • Mostly water • Contains cell's DNA in region called the nucleoid


  Cytosol
• • Unique structures produced by some bacteria • Defensive strategy against unfavorable conditions • Vegetative cells transform into endospores when nutrients are limited • Resistant to extreme conditions such as heat, radiation, chemicals


  Endospores
• • Sites of protein synthesis • Composed of polypeptides and ribosomal RNA • 70S ribosome composed of smaller 30S and 50S subunits • Many antibacterial drugs act on bacterial ribosomes without affecting larger eukaryotic ribosomes


  Ribosomes
• • Composed of three or four types of protein fibers • Can play different roles in the cell • Cell division • Cell shape • Segregation of DNA molecules • Movement through the environment


  Cytoskeleton
• • Function in the formation of biofilms • Adhere cells to one another and inanimate objects


  Glycocalyces
• • Consist of basal body, hook, and filament • Numerous differences from bacterial flagella


  Flagella
• • Many archaea have fimbriae • Some make fimbria-like structures called hami • Function to attach archaea to surfaces


  Fimbriae and Hami
• Most archaea have cell walls
• Archaeal cytoplasm similar to bacterial cytoplasm
• Archaeal cytoplasm also differs from bacterial cytoplasm
• 1. • Not as organized as prokaryotic capsules • Help anchor animal cells to each other • Strengthen cell surface • Provide protection against dehydration • Function in cell-to-cell recognition and communication


  Glycocalyces
• Fungi, algae, plants, and some protozoa have cell walls
• All eukaryotic cells have cytoplasmic membrane
• Contain regions of lipids and proteins called membrane rafts
• Receives, processes, and packages large molecules for export from cell • Packages molecules in secretory vesicles that fuse with cytoplasmic membrane • Composed of flattened hollow sacs surrounded by phospholipid bilayer • Not in all eukaryotic cells


  Golgi body
• Eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes


  Endosymbiotic theory