BCOR 1450 Module 3: Prokaryotes

Put the following key events of life on earth in order: great oxygenation event,
evolution of multicellular life, formation of earth, plants colonize land, evolution of
prokaryotes, evolution of eukaryotic cells

1. Formation of Earth

2. Evolution of Prokaryotes

3. Great Oxygenation Event

4. Evolution of Eukaryotic Cells

5. Evolution of Multicellular Life

6. Plants Colonize Land

List the three domains of life and their key characteristics

Eukaryotes ·     Membrane bound organelles ·     Membrane enclosed nucleus

Archaea ·       Lipids in cell membrane ·       More similar to eukarya

Bacteria ·       Peptidoglycan in cell wall ·       Can be pathogenic (~1/2 of all human disease)

List key characteristics of prokaryotes

·       Unicellular organisms

·       Emerged 3.5 BYA

·       Asexual reproduction

·       Circular chromosomes and plasmid (non-chromosomal DNA)

·       Lack nuclear envelope

·    Spherical, rod, and spiral shapes

Discuss genetic diversity in prokaryotes, including the role of rapid generation time,
mutation, and genetic recombination

Take a long time to diversify, two factors lead to high genetic variability:

1. Low mutation rate but fast reproduction rate= overall significant # of mutations

2. Genetic recombination

• Vertical: transmission of plasmid directly to daughter cells @ replication

• Horizontal: plasmid transferred to other bacteria of same generation

  • Transduction: bacteriophage infects bacterial cell (donor), donor replicates phage DNA, phage injects donor DNA into recipient

  • Transformation: dead cell releases DNA  into the environment, recombines with living cell

  • Conjugation: Plasmid containing cell makes physical contact/forms physical connection (conjugation tube) with cell for DNA transfer

    • Plasmid transfer: Copy of plasmid transferred via conjugation tube

    • Recombination: Portion of main chromosome copied, transferred, and recombined

List the different energy and carbon sources

Energy sources

• Phototroph: energy from sun

• Chemotroph: energy from chemical compounds

Carbon sources

• Autotroph: carbon from atmospheric CO₂

• Heterotroph: carbon from organic compounds

Define extremophiles

Microbes living in extreme habitats (pH<1, 0°C, extreme salinity)

Define the microbiome and its functions

Microbiome: community of microbes naturally inhabiting/playing key roles in body

• Nutrition: Fermentation of fiber + multivitamin production body can’t do alone

• Metabolism: Energy harvesting, obesity linked to issues with microbiome

• Immune system: Development, pathogen protection, inflammation regulation

Describe Gram Staining and the characteristics and implications of gram positive and gram negative bacteria

Combination of stains used to distinguish bacteria based on their cell wall composition

• Gram positive

  • Have a thick peptidoglycan layer in their cell wall.

  • Retain crystal violet stain, appearing purple under a microscope.

  • Lack an outer membrane, making them more susceptible to antibiotics

  • Generally easier to treat

• Gram negative

  • Have a thin peptidoglycan layer and an outer membrane

  • Do not retain the crystal violet stain, appearing pink under a microscope

  • The outer membrane blocks antibiotics, making them more resistant

  • Gram-negative infections are often harder to treat

  • May require broader-spectrum or specialized

  • Can trigger strong immune responses, leading to complications

Ecological Importance of Prokaryotes

• Crucial for nutrient cycling (e.g., nitrogen fixation and decomposition)
• Help break down organic material, returning nutrients to soil
• Contribute to atmospheric balance and ecosystem functioning

Economic Importance of Prokaryotes

• Utilized in biotechnology for producing pharmaceuticals and enzymes
• Key in bioremediation to clean up contaminated environments
• Used in fermentation processes for food products (e.g., yogurt, cheese)