Cell Biology and Characteristics of Living Organisms

Lecture Overview

  • Introduction to Lecture

    • Attendance checks and announcements regarding assignments

    • Encouragement for students to submit pre-lab assignments online or in class

Assignments and Study Tools

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    • Can assist in summarization, video watching, and exam question creation

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Overview of Course Model and Materials

  • Lecture Notes

    • Personalized notes related directly to lecture content

    • Additional resources available on modules with PowerPoints and Word documents

    • Lecture notes contain key information in paragraph format for clarity

Chapter Three Introduction: Cellular Biology

  • Focus on cellular biology

    • Definitions and importance of cells in living organisms

    • Introduce characteristics of living organisms

  • Distinction between prokaryotic and eukaryotic cells

Characteristics of Living Organisms

  1. Cellular Composition

    • All life forms must contain at least one cell

    • Prokaryotic cells (e.g., bacteria) vs. eukaryotic cells (e.g., multicellular organisms)

  2. Genetic Material

    • Living organisms possess double-stranded DNA as genetic material

    • Example: Humans have 46 chromosomes (23 pairs)

  3. Ribosomes

    • Essential structures for protein synthesis

    • Ribosomes convert DNA information into proteins

  4. Cytoplasm

    • Contains cellular components where biochemical reactions occur

    • Includes cytoskeleton for cell structure and stability

  5. Responsiveness

    • Living organisms can interact with and respond to their environment

    • Homeostasis: Maintain stable internal conditions (pH, temperature, salinity)

    • Importance of specific conditions for biochemical reactions

  6. Metabolism

    • Totality of biochemical reactions sustaining life within a cell

    • Collectively refers to growth and energy management

  7. Growth and Reproduction

    • All living cells are capable of growth and reproduction

    • Distinction between cellular growth and organismal growth

  8. Evolution

    • Organisms evolve from ancestral species over time

    • Mules as a conceptual example of species that are not viable for reproduction

Types of Cells: Prokaryotes vs. Eukaryotes

  • Prokaryotes: Simple cells (bacteria)

    • Characterized by lack of membrane-bound organelles and complexity

  • Eukaryotes: More complex cells (fungi, protozoa, plants, animals)

    • Includes organelles and structures that facilitate advanced cellular functions

Prokaryotic Cells: Bacteria

  • General Overview of Prokaryotic Cells

    • Defined as small cells with a simple structure

    • Key features: cell membrane, cytoplasm, ribosomes, possible cell wall

  • Components of Prokaryotic Cells

    • Cell Membrane: Fundamental boundary of the cell

    • Glycocalyx: Optional sticky outer layer, helps with adherence and water retention

    • Cell Wall: Typically made of peptidoglycan; provides structure and protection

    • Flagella: Structure for movement (motility)

    • Fimbriae: Hair-like appendages for attachment to surfaces

    • Conjugation Pilus: Hollow tube for genetic material exchange between bacteria

Glycocalyx Details

  • Types: Capsules (thick) and Slime Layers (thin)

    • Capsules provide stronger protection against immune response

    • Slime layers assist with moisture retention and adherence

    • Serve as biofilms where multiple bacteria can function cooperatively

Flagella in Prokaryotes

  • Used for movement via a propeller-like mechanism

  • Can vary in quantity among bacteria, influencing motility

Fimbriae in Prokaryotes

  • Sharp, stiff extensions for adhering to surfaces

  • Contribute to bacterial strength and attachment capabilities

Conjugation Pili in Prokaryotes

  • Structures allowing for genetic material exchange through direct contact with other cells

Cell Wall Structure

  • Peptidoglycan: Unique to bacteria, composed of N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG)

    • Serves as a critical target for antibiotics due to its distinct presence in bacterial cells but not in human cells.

Structural Differences: Gram Positive vs. Gram Negative

  1. Gram Positive

    • Thick peptidoglycan wall

    • Contains teichoic acids for structural support

    • Stains purple during Gram staining

  2. Gram Negative

    • Thin peptidoglycan layer between inner and outer membranes

    • Outer membrane contains lipopolysaccharides (LPS), contributing to pathogenicity

    • Stains pink during Gram staining

Importance of Gram Staining

  • Essential method for identifying bacterial types based on their cell wall structure

  • Gram-positive (purple) versus gram-negative (pink) yields critical information for treatment approaches

Exam Preparation Tips

  • Be interactive: Draw and label structures as they pertain to bacterial cells

  • Understand the functional significance of each structure

  • Practice explaining differences in cell wall types clearly

  • Concepts such as homeostasis, metabolism, and bacterial characteristics are critical H