Prokaryotes Section D part 2 plus protists part 1 to post-1 (2)

Announcements

  • Reading assignments for the coming week available on Fridays.

  • If you haven’t resolved your 0 quiz grade, come to office hours at 3 today in 488 SH.

  • Updates to grading procedures in syllabus will be made next week.

Lecture Overview

  • This lecture completes coverage of Prokaryotes (Chapter 26) and starts on Protists (Chapter 27).

Bacteria & Archaea: The "Prokaryotes" Part 2

  • Prokaryotic Cell Structure includes:

    • Cytoplasm

    • Capsule

    • Cell Wall

    • Cytoplasmic Membrane

    • Ribosomes

    • Pili

    • Nucleoid

    • Flagella

Phylogeny and Classification

  • Paraphyletic group: includes the common ancestor and some descendant taxa but is not a good cladistic category.

  • Inquiry: Are prokaryotes a monophyletic group? If not, what type of group do they form?

Diversity and Ubiquity of Prokaryotes

  • Analysis of how the diversity and ubiquity of prokaryotes are causally related.

Basic Needs of Living Organisms

  • All living organisms require:

    1. Source of high-energy electrons for making ATP:

      • Light energy (phototrophs)

      • Organic molecules (chemoorganotrophs)

      • Inorganic molecules (chemoorganotrophs)

    2. Source of carbon for complex compounds:

      • Autotrophs: use inorganic sources (e.g., CH4, CO2)

      • Heterotrophs: absorb carbon compounds produced by other organisms

Metabolic Diversity of Prokaryotes

  • Prokaryotes exhibit highly diverse metabolic niches—six possible combinations are identified.

  • Metabolic Categories for Heliobacteria:

    • Heliobacteria produces ATP from anoxygenic photosynthesis and absorbs carbon-containing molecules from decaying organic matter in soil.

    • Options:

      • Chemoorganoautotroph

      • Chemoorganoheterotroph

      • Photoautotroph

      • Photoheterotroph

      • Chemolithoautotroph

Eukaryotes Overview

Six General Methods for Obtaining Energy and Carbon

  • Source of Energy and corresponding carbon bond synthesis:

    • Phototrophs: from sunlight

      • Autotrophs: self-synthesize from CO2, CH4, or other simple molecules

      • Example: Cyanobacteria

    • Chemoorganotrophs: from organic molecules

      • Example: Methylomonas bacteria

    • Chemolithotrophs: from inorganic molecules

      • Example: Nitrosopumilus maritimus

    • Heterotrophs: from molecules produced by other organisms

      • Example: Escherichia coli

Global Impact of Prokaryotes

  • Nitrogen Fixation:

    • Some species can break N2 bonds to produce amino groups, enabling organisms to build proteins.

    • Other key cycles: carbon, phosphorus, sulfur

    • Example: Rhizobium in root nodules of legumes (nitrogenase)

Bacteria and Their Impact on Human Health

  • Examples of various bacteria causing diseases:

    • Firmicutes: Clostridium tetani, Staphylococcus aureus

    • Spirochaetes: Borrelia burgdorferi, Treponema pallidum

    • Actinobacteria, Chlamydiales, etc. include pathogens like Mycobacterium tuberculosis, Salmonella enterica.

  • Antibiotics are sourced from fungi and other bacteria.

Antibiotic Resistance

  • Lateral Gene Transfer (LGT) contributes to antibiotic resistance by sharing resistant alleles across strains and species.

  • It’s a serious concern especially in hospital settings where multi-drug resistant strains emerge.

  • Strategies to combat: sharply curtail use of antibiotics.

Role of the Gut Microbiome

  • The gut microbiome acts like a "rainforest" with over 1,000 species impacting health conditions, including diabetes type 2 and autoimmune disorders.

Koch's Postulates

  • Self-study: Understand Koch’s postulates for linking pathogens to diseases.

  • Postulates consist of four steps to confirm causative links between diseases and specific microbes. Challenges include unculturable microbes and asymptomatic carriers.

Bioremediation

  • Definition: use of living organisms to degrade pollutants.

  • Prokaryotes utilized for cleaning oil spills and chemical solvents.

Evolution and Metagenomics

  • Metagenomics: offers insights into microbial community composition through DNA sequencing, revealing interdependencies among species and the limits of culture-based methods.

Summary

  • Prokaryote metabolic diversity is crucial for ecosystems and useful for humans.

  • Traditional classification raises questions about species definitions, and LGT challenges the concept of evolution. Biofilms in the small intestine illustrate interactions with eukaryotes.