Biodiversity and Genetic Diversity Overview

Biodiversity

• Species Diversity: Refers to the variety and abundance of species within a given area.
• Genetic Diversity: Measures the variety of heritable characteristics among interbreeding individuals within a species. This is known as the gene pool, the sum of all gene versions in a population.
• Ecosystem Diversity: The variety of ecosystems in the biosphere, encompassing both biotic (living) and abiotic (non-living) components, creating diverse physical and chemical landscapes. Ecosystems provide numerous services.
  • Ecosystem Services: Benefits organisms (including humans) receive from sustainable ecosystems, such as habitat for wildlife, ecotourism opportunities, and pest control.

Genetic Diversity

• Gene Function: Genes control trait expression and inheritance. Genetic differences cause individual variations.
• Resistance to Disease: Genetic diversity within a population increases its ability to survive environmental changes, including disease outbreaks. If all individuals lack resistance, the entire population could be wiped out.
• Conservation Biology: Understanding genetic diversity helps conservation efforts by aiding struggling populations.

Prokaryotes (Bacteria and Archaea)

• General Characteristics: Single-celled, small (less than 2 micrometers), lack membrane-bound organelles. Organelles are not enclosed by membranes.
• Structure:
  • Cell Wall: Provides structural support and protection; made of peptidoglycan (bacteria) or other materials (archaea).
  • DNA: Forms a circular plasmid, much smaller than eukaryotic DNA.
  • Capsule: Allows prokaryotes to attach to surfaces and protects them from immune system attack; prevents dehydration.
  • Cell Membrane: Controls substance movement in and out of the cell.
  • Nucleoid Region: Contains DNA, RNA, and associated regions.
  • Pili: Hair-like structures on the cell surface with various functions (genetic exchange, movement, attachment).
  • Flagellum (some bacteria): Tail-like structure used for movement.
  • Cilia (some bacteria): Projections used for movement.

Differences Between Bacteria and Archaea

• Cell Wall and Membrane: Bacteria cell membranes have a phospholipid bilayer, and cell walls have peptidoglycan. Archaea cell wall and membrane structures differ significantly and resemble more closely those of eukaryotes.
• Extreme Environments: Archaea are often found in extreme environments (e.g., high temperatures, high salinity).
• Methanogens: A type of archaea that produce methane as a byproduct in oxygen-free environments.
• Mutualistic Relationships: Some archaea have mutualistic relationships with other organisms (ex: some help with digestion).
• Metabolic Diversity: Bacteria exhibit various types of metabolism, respiration and other cell function variations based on their characteristics of cell wall, movement, and metabolism.
  • Gram Stain: Classification of bacteria based on their reaction to a dye (crystal violet and iodine). Gram-positive bacteria absorb the stain; gram-negative bacteria don't. Gram-negative bacteria are often more pathogenic (disease-causing).

Bacterial Reproduction

• Binary Fission: Asexual reproduction where a cell replicates its DNA and divides into two identical daughter cells; rapid reproduction rate (e.g., every 20 minutes).
• Conjugation: Transfer of genetic material between bacterial cells via a pilus, increasing genetic diversity. This often involves exchanging plasmids.
• Endospore Formation: Some bacteria form endospores to protect their DNA from environmental stressors (e.g., high temperature, lack of nutrients). Endospores can remain dormant for long periods and then germinate into active bacteria.

Antibiotic Resistance

• Mechanism: Antibiotics disrupt bacterial cell wall formation, metabolic processes, or reproduction.
• Development: Mutations in bacteria can lead to antibiotic resistance, which is often transferred via conjugation, increasing quickly in a population because of the reproduction rate.

Viruses

• Definition: Non-living, non-cellular infectious agents. They depend entirely on a host cell to carry out their life cycle functions (replication, metabolism).
• Size: Extremely small (less than 0.1 micrometers in diameter).
• Structure: Contain genetic material (DNA or RNA) surrounded by a protein coat.

This quiz explores the concepts of biodiversity, species diversity, genetic diversity, and ecosystem diversity. It also delves into the importance of genetic variation in populations and its impact on resilience against disease and environmental changes. Test your understanding of these critical ecological concepts!