2.1- Prokaryotic Cell Structure Part 1

Introduction

  • Presenter: Dr. Narelle Hunter

  • Focus of Lecture: Structure of Prokaryotic Cells

  • Recommended Reading: Chapter 6 of the textbook, with Chapters 2-5 as assumed knowledge.

Learning Outcomes

  • Understand the microscopic structure of cells.

  • Cells as fundamental units of life.

  • Common features among diverse cell types.

Importance of Cells

  • Cells are the foundation of all life.

  • Study of biology revolves around cell structures and functions.

Common Features of All Cells

  • Plasma Membrane: All cells are bounded by this structure.

  • Cytosol: Contains a semi-fluid substance within the cell.

  • Chromosomes: Carries genetic information in the form of DNA.

  • Ribosomes: Complexes that make proteins based on genetic instructions.

Classification of Cells

Types of Cells

  • Prokaryotic Cells: Include bacteria and archaea.

  • Eukaryotic Cells: All other living organisms, including animals, plants, and fungi.

Cell Naming and Features

  • Prokaryotic: "Pro" means before; "karyon" means nucleus (no true nucleus).

  • Eukaryotic: "Eu" means true; cells have a true nucleus.

Size Comparison

  • Prokaryotic Cells: Generally 1 to 10 micrometers, not visible to the naked eye.

  • Eukaryotic Cells: Typically 10 to 100 micrometers; examples include nerve cells which can be up to 1 meter long.

Prokaryotes

  • Historical Context: Dominant life forms on Earth for 3.5 to 2 billion years.

  • Structure: Lack a nucleus; DNA is in the nucleoid region.

  • Reproduction: Fast reproduction through binary fission (asexual reproduction).

  • Examples:

    • Vibrio natrigens: Fastest growth rate <10 min doubling time.

    • E. Coli: Commonly found in intestines, with a doubling time of ~20 minutes.

Shapes of Prokaryotes

  • Cocci: Spherical shape.

  • Bacilli: Rod-shaped.

  • Spiruli: Helical shape.

Metabolic Adaptations of Bacteria

  • Obligate aerobes: Require oxygen for metabolism.

  • Anaerobes: Do not require oxygen (includes obligate and facultative anaerobes).

Positive Roles of Bacteria

  • Importance in human health, particularly gut health and diseases like IBS.

  • Probiotics: Beneficial bacteria aiding in digestion.

Research Advances

  • Study example from Japan relates gut microbiome to dementia.

  • Complexity of bacterial relationships in health yet to be fully understood.

Discovery Challenges

  • Approximately 30,000 bacterial species formally identified; many undiscovered.

  • Typical methods are inadequate for discovering new bacterial species due to growth requirements.

  • Innovation in Research:

    • Professor Slava Epstein researching new antibiotics derived from undiscovered bacteria.

    • Example experiment used mouth retainers for bacteria cultivation.

Importance of Bacterial Cell Wall

  • Provides shape, protection, and prevents bursting in hypotonic environments.

  • Gram Staining: Laboratory technique to analyze cell wall composition through color differences.

Conclusion

  • Understanding bacteria is crucial due to their vast diversity and role in ecosystems.

  • Further research is necessary to uncover more about prokaryotic cells and their applications in medicine.