Cell

• Cellular Microorganism


  Organism that contain cells, either unicellular or multicellular
• Types of Cellular Microorganisms

  • Unicellular - Prokaryotes (Archaea, Bacteria, Cyanobacteria)
  • Unicellular/Multicellular - Eukaryotes (Algae, Fungi, Protozoa)
• Acellular Microorganism


  Organism that doesn't contain cells

  
• Acellular Microorganisms


  • Virus
  • Viroids
  • Prions
• Prokaryotic cell


  • "no true nucleus"
  • 0.2 - 2.0 μm diameter
  • 2 - 8 μm length
  • Lack membrane-enclosed organelles
  • No cytoskeleton
  • Transverse binary fission
  • Monomorphic or pleomorphic
• Archaea


  • Means ancient
  • Look identical microscopically to members of the bacteria domain
  • Do not have peptidoglycan
  • Have the ability to grow in extreme environments (hot/cold, acidic/alkaline, extreme salt concentration)
• Bacteria


  • Single-celled prokaryote (a simple cell with a nucleoid region, surrounded by cytoplasm and a cell wall)
  • Shapes: Bacili - rod-shaped, Cocci - spherical-shaped, Spirilla - spiral-shaped
  • Multiply by binary fission (one cell divides into two cells, identical to the original)
• Prokaryotic Cell Structure - Appendages

  • Glycocalyx
  • Flagella
  • Fimbriae
  • Pili
  • Axial filaments

  
• Glycocalyx


  • The outer layer usually made up of bound polysaccharides on the cell surface and superficial layer of unbound proteoglycans and glycoproteins
  • Capsule - Anti-phagocytic function, Vaccine target, attachment
  • Slime layer - Glide or slide on surfaces, Formation of biofilm

  
• Flagella


  • Long, slender, threadlike, whip-like extension of certain cells or unicellular organisms used mainly for movements (others for signal transduction)
  • Arrangements: Atrichous, Monotrichous, Lophotrichous, Amphitrichous, Peritrichous
• Fimbriae


  • Hair-like structures made of "pilin"
  • Enable bacterial cell to adhere to surfaces

  
• Pili


  • Short, filamentous projection on a bacterial cell, used not for motility but for adhering to other bacterial cell (especially for mating) or to animal cells
  • Joins bacterial cell for DNA transfer during conjugation
  • "sex pili"
• Axial filaments


  Flagella-like fibrils arising at the ends
• Prokaryote: Cell Wall


  • Composed of peptidoglycan (murein)
  • N-acetylglucosamine (NAG)
  • N-acetylmuramic acid (NAM)
  • Used to characterized bacterial cells: Gram Positive - teichoic acid and lipotechoic, Gram Negative - lipoproteins, LPS and phospholipid
• Differences Between Gram Positive and Gram Negative Organisms

  • Staining
  • Cell Wall
  • Outer Membrane
  • Peptidoglycan
  • Lipid Content
  • Periplasmic Space
  • Flagella
  • Spores
  • Pili
• Plasmid


  Contains extra-chromosomal DNA which carry genes that confer protective trait that may be duplicated and passed on to an offspring

  
• Ribosome


  A minute particle composed of protein and ribonucleic acid (RNA) that serves as the site of protein synthesis
• Inclusions


  An abnormal structure in a cell nucleus or cytoplasm having characteristic staining properties
• Endospore


  Bacteria undergo sporulation during exposure to harsh conditions
• Comparison of Three Cellular Domains

  • Cell Type
  • Chromosomes
  • Types of ribosome
  • Contains unique ribosomal RNA signature sequence
  • Number of sequences shared with Eukarya
  • Protein Synthesis similar to Eukarya
  • Presence of peptidoglycan in cell wall
  • Cell Membrane lipids
  • Sterols in membrane
• Eukaryotic Cell (Eukaryotes)


  • All members of the living world except the prokaryotes are considered Eucarya
  • Single celled and multi-celled
  • Contain basic organelles: cell membrane, cytoplasm, nucleus
  • Membrane bound "true" nucleus
  • Ave size: 10 – 30 μm
  • Mitosis/meiosis
• Examples of Eukaryotes


  • Algae
  • Fungi
  • Protozoa
• Algae


  • Photosynthetic eukaryotes with a wide variety of shapes that occur in most habitats, ranging from marine and freshwater to desert sands and from hot boiling springs to snow and ice belonging to Kingdom Protista
  • Small, single - celled forms (filamentous) to most complex multicellular forms
  • They are not plants, they are more plantlike than protozoa. Algae lack true roots, stems and leaves
  • They play an important role in balancing the environment
• Examples of Algae


  • Chlamydomonas
  • Spirogyra
  • Rhodymenia
• Fungi


  • Can be single-celled or very complex multicellular organisms
  • Found in any habitat but most live on the land, mainly in soil or on plant material rather than sea or fresh water
  • Decomposers grow in the soil or on dead plant matter where they play an important role in the cycling of carbon and other elements
• Examples of Fungi


  • Yeast
  • Molds
• Protozoa


  • Protozoa are single-celled organisms. They come in many different shapes and sizes ranging from an Amoeba which can change its shape to Paramecium with its fixed shape and complex structure
  • They live in a wide variety of moist habitats including fresh water, marine environments and the soil
  • Some are parasitic, which means they live in other plants and animals including humans, where they cause disease
  • Plasmodium, for example, causes malaria. They are motile and can move by means of flagella, cilia, and amoeboid movement

  
• Cells Organelles and its Functions

  • Ribosomes (protein synthesis)
  • Cytoskeleton (Shape, support, endocytosis in eukaryotes)
  • Centrosome (Role in mitosis, cytokinesis, flagella and cilia formation in animal cells)
  • Nucleus (Contains DNA and is the control center)
  • ER (Transport nutrients within cell, lipid synthesis (EUK: contains ribosome make proteins))
  • Golgi Bodies (Exocytosis, secretion, protein packaging)
  • Lysosomes (Breakdown nutrients, self-destruct aged or bad cell)
  • Peroxisomes (Neutralization of toxins)
  • Vacuoles (Storage and maintain hydrostatic equilibrium)
  • Vesicles (Storage,digestion, transport)
  • Mitochondria (Aerobic ATP production)
  • Cholorplasts (Photosynthesis)
• Virus


  • Considered acellular, non-living, obligate intracellular parasite
  • Made of core containing DNA or RNA surrounded by a protein coat
  • Can reproduce only by using the cellular mechanisms of another cell
  • Considered the parasites of the microbial world
• Viroids


  • Very small, circular RNA (may appear linear), and infectious in plants. They do not contain a capsid
  • The only human disease known to be caused by a viroid is hepatitis D; in this case the viroid is enclosed in a hepatitis B virus capsule
• Prions


  • Contain only protein
  • Causative agent for some neurodegenerative diseases in humans and animals
• Comparison Between Prokaryote and Eukaryote

  • Typically Smaller
  • Compartmentalized by membrane-bounded sacs or organelles
  • Contain nucleus with multiple chromosomes
  • Divide by complex process of mitosis

  
• Difference of Prokaryotes from Eukaryotes

  • Nuclear Properties
  • Cytoplasm Properties
  • Microtubules
  • Centrioles
• Cell organelles


  • mitochondria
  • chloroplasts
  • endoplasm
  • reticulum
  • Golgi apparatus
  • central vacuoles
• Respiratory enzymes and other components

  • Found in the cell membrane
• Mitochondria


  • Double membrane bound
  • Meant for aerobic respiration
• Photosynthetic components in photosynthetic prokaryotes

  • Found in membranous sacs or tubes, called thylakoids
• Chloroplasts in photosynthetic eukaryotes

  • With grana and stromal thylakoids
  • Perform photosynthesis
• Microtubules and microfilaments are absent
• Cytoplasm


  • Contains a network of microtubules and microfilaments made up of proteins
  • Functions as the cytoskeleton