PowerPoint 3a - The Cell copy

Page 1: Introduction

• COLLEGE PHYSICS Chapter #

• Title: Microbiology

• This PowerPoint has been modified for BIO 275 (CVCC).

• Much of the work is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

• Textbook and student resources available at OpenStax.

Page 2: Microorganisms

• Microorganisms vary in:

  • Size and Shape: Observable microscopically.

  • Metabolic Capabilities: Not visible but crucial for classification.

Page 3: Spontaneous Generation

• Early misconceptions in science:

  • People believed living things arose from nonliving things, termed spontaneous generation or abiogenesis.

  • Example: Flies appearing on raw meat led to the belief that meat generates flies.

Page 4: Francesco Redi's Experiment

• In 1668, Francesco Redi conducted an experiment with:

  • Open container

  • Cork-sealed container

  • Gauze-covered container (permits air but blocks flies).

• Result: Maggots appeared only in open containers, disproving spontaneous generation doubtfully.

Page 5: Needham and Spallanzani

• John Needham (1745):

  • Argued microbes arose from a "life force" in broth but did not sufficiently boil it or sealed it.

• Lazzaro Spallanzani:

  • Repeated Needham's work with closed containers, which did not grow microbes, disproving Needham's idea.

Page 6: Louis Pasteur and Closure on Spontaneous Generation

• The Paris Academy of Sciences incentivized disproving spontaneous generation.

• Louis Pasteur:

  • Filtered air showing microorganisms.

  • Microorganisms did not grow in sealed boiled flasks.

  • Conclusion: No "life force" was necessary for microbial growth.

Page 7: Swan-Neck Flasks and Aseptic Techniques

• Pasteur’s swan-neck flasks allowed air in but prevented microbial contamination.

• Proved microorganisms arise from existing life (biogenesis), not spontaneity.

Page 8: Pasteur's Experimental Setup

• Details of Pasteur's swan-neck flask experiment:

  • Part 1: Flask boiled and cooled remained uncontaminated.

  • Part 2: Broken neck led to contamination, validating need for sealed conditions.

Page 9: Development of Cell Theory

• Recognition that cells are the smallest life units took time:

  • Matthias Schleiden (1838): All plant life made of cells but misunderstood their formation.

  • Theodor Schwann (1839): All animals made of cells, establishing cell theory.

Page 10: Further Evidence of Cell Theory

• Robert Remak and Rudolf Virchow:

  • Remak (1852): Cells come from other cells via division.

  • Virchow (1855): Popularized the idea that life arises from life.

Page 11: Historical Contributions to Cell Theory

• Rudolf Virchow's key contributions:

  • Cellular Pathology outlined the origin of cells from other cells.

Page 12: Advancements in Microscopy

• Improved microscopes led to studying organelles.

• Discovery of chloroplast reproduction in late 1800s.

• Notable findings in 1960s about mitochondria and chloroplasts having their own DNA.

Page 13: Endosymbiotic Theory

• Lynn Margulis proposed:

  • Mitochondria and chloroplasts derived from prokaryotic bacteria.

  • Initially met with skepticism but gained acceptance.

Page 14: Endosymbiotic Theory Explained

• Endosymbiotic theory: Mitochondria and chloroplasts from bacteria that formed a symbiotic relationship with host cells.

Page 15: Ignaz Semmelweis and Hygiene in Medicine

• Semmelweis (1847): Noticed maternal mortality due to lack of handwashing among physicians.

• Proposed handwashing led to lower infection rates.

Page 16: Significance of Semmelweis's Work

• Semmelweis emphasized handwashing to prevent disease transfer in medical settings.

Page 17: Contributions of John Snow

• John Snow (1848): Linked cholera to contaminated water, not miasmas.

• His mapping of cholera cases significantly contributed to public health.

Page 18: Pasteur's Discoveries on Fermentation

• Investigation by Pasteur into spoilage due to microorganisms involved in fermentation.

• Introduced pasteurization to kill spoilage-causing bacteria by heating.

Page 19: Joseph Lister's Surgical Innovations

• Lister (1860s) advocated for sterilization and cleanliness during surgery to prevent infections.

Page 20: Development of Germ Theory

• Robert Koch established postulates linking specific diseases to specific microbes, solidifying germ theory.

Page 21: Impact of Lister and Koch on Germ Theory

• Joseph Lister and Robert Koch significantly contributed to the acceptance and application of germ theory in medicine.

Page 22: Timeline of Microbiology Milestones

• Overview of significant contributions:

  • Ancient Greeks propose miasma theory.

  • 1665: Hooke observes cells.

  • 1854: Snow links cholera to water.

  • 1862: Pasteur disproves spontaneous generation.

Page 23: Cell Types

• Two main cell types:

  • Prokaryotic Cells: No membrane-bound nucleus (Bacteria, Archaea).

  • Eukaryotic Cells: Contains membrane-bound nucleus (Eukarya).

Page 24: Characteristics of Prokaryotic Cells

• Prokaryotic cells lack membrane-bound organelles, have a circular DNA structure and a protective cell wall.

Page 25: Characteristics of Eukaryotic Cells

• Eukaryotic cells possess membrane-bound organelles, multiple linear chromosomes, and may or may not have cell walls.

Page 26: Structure of Prokaryotic Cells

• Prokaryotic cell anatomy:

  • Cell membrane, nucleoid with DNA, ribosomes, and potentially flagella and capsules.

Page 27: Osmotic Pressure and Prokaryotic Cells

• Cell Walls: Protect cells from osmotic pressure changes.

• Cellular environment increased through water and solutes influences cell survival.

Page 28: Understanding Osmosis

• Osmosis: Movement of water through a semipermeable membrane from high water concentration to low.

Page 29: Water Movement Predictions

• Water movement influenced by solute concentrations:

  • Isotonic: Equal concentrations.

  • Hypertonic: Higher concentration externally.

  • Hypotonic: Lower concentration externally.

Page 30: Cell Wall Responses to Osmosis

• Response of prokaryotic cells to osmotic environments:

  • Isotonic: normal state.

  • Hypertonic: plasmolysis.

  • Hypotonic: can lead to cell lysis.

Page 31: Effects of Hypertonic Environments

• Cells without walls experience crenation in hypertonic environments, while those with walls undergo plasmolysis.

Page 32: Impact of Hypotonic Environments

• Cells in hypotonic environments can undergo lysis, predominately those lacking cell walls.

Page 33: Prokaryotic Cell Shapes

• Shape maintenance in prokaryotes provided by cell wall structure; variations include spirilla, spirochetes, and pleomorphism.

Page 34: Bacterial Arrangements

• Bacterial cells can arrange into specific structures:

  • Example: Sarcinae, cube-like arrangements of bacterial cells.

Page 35: Nucleoid Region of Prokaryotic Cells

• Prokaryotic nucleoid region characteristics:

  • Contains a single, circular DNA strand, haploid in nature.

Page 36: Appearance of the Nucleoid Region

• The nucleoid region appears lighter under an electron microscope due to its density.

Page 37: Organization of DNA in Prokaryotes

• Domain Bacteria and Archaea organize DNA differently with nucleoid-associated proteins and, in some cases, histones.

Page 38: Plasmids in Prokaryotic Cells

• Plasmids are small, circular strands of DNA providing genetic advantages such as antibiotic resistance and they replicate independently.

Page 39: Ribosomes in Protein Synthesis

• All life forms utilize ribosomes for protein synthesis; they vary in size and structure between prokaryotic and eukaryotic cells.

Page 40: Ribosome Size

• Prokaryotic ribosomes are classified as 70S due to sedimentation rates; consist of small (30S) and large (50S) subunits.

Page 41: Prokaryotic Ribosome Composition

• Composition and comparison of ribosomes in Bacteria and Archaea; implications for antibiotic action.

Page 42: Ribosomes and Antibiotic Effects

• Targeting bacterial ribosomes provides treatment opportunities without harming eukaryotic cells.

Page 43: Inclusions in Prokaryotic Cells

• Inclusions are nutrient reserves in prokaryotic cells, contributing to osmotic balance and potentially identifying species.

Page 44: Types of Inclusions

• Examples of inclusions include:

  • Glycogen granules.

  • Volutin granules (polyphosphate).

  • Lipid storage inclusions.

Page 45: Specialized Inclusions

• Specialized inclusions serve different functions:

  • Sulfur granules: Energy reserves in sulfur bacteria.

  • Magnetosomes: Iron oxide inclusions aiding in orientation.

Page 46: Microscopic Views of Inclusions

• Visual representations of various types of inclusions found in prokaryotic cells.

Page 47: Vegetative Cells vs Endospores

• Bacterial cells can be vegetative or form endospores under unfavorable conditions, with endospores providing genetic material protection.

Page 48: Formation Process of Endospores

• Sporulation process involves a complex transformation protecting genetic material from harsh environments.

Page 49: Endospore Resistance

• Endospores' resilience to extreme conditions such as heat and chemicals, leading to long-term survival.

Page 50: Clinical Relevance of Endospores

• Importance of endospores in pathogenic bacteria and implications for public health and bioterrorism.

Page 51: Endospore Formation Visuals

• Diagrams depicting the process and stages of endospore formation in bacterial cells.