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.