Unit 4

LIFE REVIEW AND PROKARYOTIC CELLS

  • Basic Structures of Prokaryotic Cells

    • Plasma membrane
    • Cell wall
    • Capsule
    • Cytoplasm
    • Ribosome
    • Nucleoid
    • Pilus
    • Flagellum
    • Inclusion
    • Plasmid

  • Visual References: Pictures of

    • Helicobacter pylori
    • Cartoon bacterial cell
    • Streptococcus mutans
    • Borrelia burgdorferi

HOW DO YOU KNOW THAT A LIVING THING IS LIVING?

  • Prompts for Reflection:
    • Sit with this one for a bit
    • Ask a friend or someone that you live with
    • Make a list

HOW DO YOU KNOW THAT A LIVING THING IS LIVING?

  • Key Characteristics of Life:

    • Cellular nature:

    • All living things are composed of cells, serving as the basic unit of life.

    • Metabolism:

    • The set of life-sustaining chemical reactions that include catabolism and anabolism.

    • Example: Energy production from food and chemical processes.

    • Generative Processes:

    • Processes that result in growth and reproduction.

    • Include processes such as division and replication.

    • Responsive Processes:

    • Interaction with the environment.

    • Includes reactions to stimuli, such as movement towards light.

    • Control Processes:

    • Regulatory mechanisms that maintain homeostasis, adapting to changes both externally and internally.

  • Further Study Resource:

THE BACTERIUM

  • Basic Bacterial Structures:

    • Plasma membrane
    • Cell wall
    • Capsule
    • Pilus
    • Flagellum
    • Fimbriae
    • Cytoplasm
    • Ribosome
    • Nucleoid
    • Inclusion
    • Plasmid

  • Visual Reference: Figure of bacterial cell model displaying all possible parts present.

BACTERIAL CELL MORPHOLOGY

  • Shapes of Prokaryotic Cells:
    • Illustrated in Table 3.13:
    • Includes various names of prokaryotic cell shape types and corresponding images (cartoons and electron microscope photographs).

BACTERIAL CELL ARRANGEMENT

  • Description of Cell Arrangements:
    • Illustrated in Table Figure 3.14:
    • Names of distinct cell arrangements along with descriptions and cartoons.

GRAM POSITIVE vs GRAM NEGATIVE CELL WALL

  • Peptidoglycan Structure:

    • Illustrated in Figure 3.25:
    • Differences between the peptidoglycan layers of Gram-positive and Gram-negative cell walls, highlighting the crosslinking of peptide components with sugar chains.

  • Complete Cell Wall Structures:

    • Illustrated in Figure 3.26:
    • Detailed structural comparison of Gram-positive and Gram-negative cell walls.

GRAM POSITIVE AND GRAM NEGATIVE EXTRA BITS

  • Components:
    • Teichoic acids
    • Porins
    • Visual reference in Figure 3.28, showing three-dimensional representations and details of the lipopolysaccharide (LPS) molecule.

THE GRAM STAIN

  • Process of Gram Staining:

    • Illustrated in Table and Figure from Foundations in Microbiology:
    • Steps:
      1. Crystal Violet (primary dye)
      2. Gram's iodine (mordant)
      3. Alcohol (decolorizer)
      4. Safranin (red dye counterstain)
    • Results:
    • Gram-positive: cells retain the crystal violet and appear purple.
    • Gram-negative: cells lose the violet stain and take up the red safranin, appearing pink.

  • Cellular Dynamics:

    • Description of how dye crystals are trapped or not retained based on cell wall differences.

WHACKY WALLS - Mycobacteria

  • Unique Features:

    • Presence of mycolic acids
    • Visual reference:
    • Cartoon of Gram-positive wall with mycolic acids.
    • Microscopy images of Mycobacteria post-acid-fast stain.

  • Cultural Growth:

    • Images of Mycobacterial colonies grown on agar.

WHACKY WALLS - Mycoplasma

  • Lack of Cell Wall:
    • Description of Mycoplasma cells, which display multi-shaped forms due to the absence of a cell wall.
    • Visual reference showing various shapes of Mycoplasma.

CELL MEMBRANE STRUCTURE

  • Components:
    • Overview showing:
    • Phospholipids
    • Integral proteins
    • Peripheral proteins
    • Glycolipids
    • Glycoproteins
    • Spatial relationships among these components depicted in Figure 3.21.

CELL MEMBRANE FUNCTIONS

  • Primary Functions:
    • Acts as a barrier
    • Functions as a gatekeeper for the following:
    • Nutrients
    • Wastes (products of metabolism)
    • Gases (Oxygen, Carbon dioxide)
    • Exoenzymes
    • Involvement in energy production and cell wall synthesis.
    • Important for creating chemical and electrical gradients.

CELL MEMBRANE FUNCTIONS: DIFFUSION

  • Diffusion Process:
    • Figure illustrating diffusion across a cell membrane over time, leading to equilibrium.
    • Stages of diffusion depicted:
    • Initial concentration on one side
    • Intermediate state with partial diffusion
    • Final state of equilibrium.

CELL MEMBRANE FUNCTIONS: FACILITATED DIFFUSION

  • Mechanism:
    • Uses protein channels to assist substances in following their concentration gradient across the membrane.
    • Reference Figure 3.23.

CELL MEMBRANE FUNCTIONS: ACTIVE TRANSPORT

  • Process:
    • Illustrated in Figure 3.24:
      • Sodium and potassium pumps utilizing ATP to transport ions either against or in accordance to concentration gradients.

CELL MEMBRANE FUNCTIONS: WITH NO WALL

  • Environmental Impact:
    • Panel illustrations showing consequences for cells without cell walls in isotonic, hypertonic, and hypotonic environments.

CELL MEMBRANE FUNCTIONS: WITH WALL

  • Environmental Impact:
    • Panel illustrations depicting the consequences for cells with cell walls held in varying environmental conditions (isotonic, hypertonic, hypotonic).

FLAGELLA

  • Structural Representation:

    • Comparison between Gram-positive and Gram-negative flagella structures shown in Figure 3.31.
    • No visible differences in flagellar structure; however, basal body placement varies.

  • Flagella Movement:

    • Describes clockwise and counterclockwise rotations associated with bacterial movement.
    • Positive chemotaxis is illustrated as bacteria move towards attractants.

FIMBRIAE AND PILI

  • Examples:
    • Image of Escherichia coli with numerous fimbriae.
    • Connection shown between bacterial cells via pili.
    • Lower images depict attachment to intestine.

GLYCOCALYX**

  • Types of Glycocalyx:

    • Tight Glycocalyx (capsule)
    • Loose Glycocalyx (slime layer)
    • Reference visuals illustrating differences.

  • Capsule Definition:

    • Composed of an organized layer of polysaccharides.
    • Example: Capsule stain of Pseudomonas aeruginosa shown with microscope images.

GLYCOCALYX FUNCTION

  • Overview of functions and implications of glycocalyx in prokaryotic cells.

CYTOPLASM

  • General description and functions within the prokaryotic cell.

DNA

  • Nucleoid Region:
    • Description of naked DNA present in prokaryotic cells.
    • Importance of lack of membrane around DNA highlighted.
    • Visualization: Figure 3.17 showing DNA structure and location within the cell.

RNA

  • Prokaryotic Ribosomes:
    • Composed of two subunits:
    • 30S (small subunit)
    • 50S (large subunit)
    • Contains rRNA and protein components.
    • Reference Figure 3.18 provides an illustration.

STORAGE

  • Types of Inclusions in Prokaryotic Cells:
    • Various storage inclusions illustrated through micrographs:
    • Polyhydroxybutyrate lipid droplets
    • Volutin granules
    • Sulfur granules
    • Magnetosomes
    • Gas vacuoles.
    • Examples from exploratory micrographs provided in Figure 3.19.

CYTOSKELETON

  • Definition and Function:
    • Composed of actin-like proteins contributing to the structural integrity and functions of prokaryotic cells.

ENDOSPORES

  • Overview and Formation:
    • Description of endospore formation and significance illustrated in Figure 3.20.
    • Visuals showing endospores alongside living cells demonstrating key aspects of their lifecycle.