BIOL 2460 Chapter 3 slides

Chapter Overview

  • Topic Overview:

    • 3.1 Spontaneous Generation

    • 3.2 Foundations of Modern Cell Theory

    • 3.3 Prokaryotic Cell Structure

    • 3.4 Eukaryotic Cell Structure

3.1 Spontaneous Generation

  • Definition: Ancient belief that life arises from nonliving matter

  • Disproof: Golden age of microbiology

  • Key Scientists:

    • Francesco Redi (1600s) - Disproved

    • John Needham (1700s) - Initially supported; misinterpreted results of boiled broth

    • Lazzaro Spallanzani (1700s) - Replicated entrees, disproved Needham

    • Louis Pasteur (1800s) - Swan Neck Experiment; disproved spontaneous generation conclusively

3.2 Foundations of Modern Cell Theory

  • Tenets:

    1. All living organisms are composed of one or more cells.

    2. Cells arise from existing cells.

  • Key Contributors:

    • Robert Hooke (1665) - Cork tissue; coined "cell"

    • Matthias Schleiden (1838) - Plant tissues

    • Theodor Schwann (1839) - Plant and animal cell comparison

    • Rudolf Virchow (1855) - emphasized cellular origin

Endosymbiotic Theory

  • Origin Theory: Proposes that mitochondria and chloroplasts originated from prokaryotic cells

  • Key Figures:

    • Konstantin Mereschkowski (1905)

    • Ivan Wallin (1926)

    • Lynn Margulis (1967) - Defined symbiotic relationship

  • Supporting Evidence: DNA, ribosomes, binary fission

Germ Theory of Disease

  • Definition: Microbial infections can cause diseases

  • Pioneers:

    • Girolamo Fracastoro (1546)

    • Ignaz Semmelweis (1847) - Promoted handwashing

    • John Snow (1848) - Linked cholera outbreaks to sewage

    • Louis Pasteur (1856) - Spoilage related to microorganisms

    • Robert Koch (1884) - Koch’s postulates related microbes to diseases

3.3 Prokaryotic Cell Structure

  • Common Elements:

    1. Cytoplasm

    2. Plasma Membrane

    3. Chromosomes

    4. Ribosomes

  • Domains:

    • Bacteria

    • Archaea

  • Unique Elements:

    1. Nucleoid

    2. Plasmids

    3. Fimbriae

    4. Endospores

  • Cell Wall Functions: Protect against osmotic pressure

  • Cell Shapes: Coccus, bacillus, vibrio, spirillum

3.4 Eukaryotic Cell Structure

  • Unique Elements:

    1. Nucleus

    2. Mitochondria

    3. Endoplasmic Reticulum

    4. Golgi Apparatus

    5. Lysosomes

    6. Peroxisomes

    7. Cytoskeleton

    8. Chloroplasts (in plants)

  • Key Components of Cytoskeleton:

    1. Microfilaments

    2. Intermediate filaments

    3. Microtubules

  • Membrane Transport: Similar to prokaryotes, including diffusion, facilitated diffusion, active transport, endocytosis, and exocytosis

  • Composition of Cell Walls: Defined by organism type - peptidoglycan (bacteria), cellulose (plants), chitin (fungi) and others

Summary of Cell Structures

  • Comparison of Prokaryotes vs. Eukaryotes:

    • Size, genetic material, cell division, organelles present, and cell wall structure vary greatly between the two.

  • Essential differences between Gram-negative and Gram-positive bacteria with respect to cell wall composition and structure.