BIO153 Lecture 2 notes

Overview of Survival Mechanisms of Life

  • Unique survival mechanisms in organisms developed through evolution.

    • Variations in shapes and forms are linked to these mechanisms.

Forms of Life and Survival

  • Survival Mechanisms

    • Organisms depend on interactions with their environment.

    • Example: Flight in birds (e.g., Rock Dove, Vagrant darter).

Interaction with Environment

  • Organisms don’t exist in isolation; interactions are vital for survival.

    • Flowering plants rely on pollen for reproduction

    • Pollen dispersal methods include wind and biotic agents like bees.

Mammalian Reproduction Strategies

  • Types of Mammals:

    • Monotremes: Lay eggs.

    • Marsupials: Give early birth, young develop in pouches (e.g., kangaroo, opossum).

    • Placental Mammals: Long gestation before birth.

  • Early divergence of marsupials from placental mammals occurred approximately 140 million years ago.

  • Mammals emerged around 225 million years during the triassic period.

Basic Requirements for Survival

  1. Energy Source: Life requires energy for survival.

    • Energy often derived from sunlight or chemical sources.

  2. Carbon as Building Block: Organisms utilize carbon to build organic molecules.

    • Carbon source primarily from
      CO2CO_2
      in the atmosphere.

    • Important organic examples include:

      • ATP (Adenosine triphosphate)

      • Glucose and amino acids (e.g., Threonine).

Photosynthesis and Food Chains

  • Primary producers convert CO2 to sugars, feeding other organisms.

  • At each energy transfer, energy is lost; no conversion is 100% efficient.

  • Carbon cycles need continuous energy input (e.g., from sunlight).

Organism Categorization by Energy Use

  • Photoautotrophs:

    • Use light (sunlight) for energy.

    • Use CO2CO_2 for carbon.

    • Examples include cyanobacteria, algae, and plants.

  • Chemoheterotrophs:

    • Acquire energy and carbon from organic molecules.

    • Includes most animals and fungi (e.g., E. coli).

      Photoheterotrophs: Acquire energy from light and carbon from organic compounds, often found in certain bacteria.

    • Chemoautotrophs: Obtain energy by oxidizing inorganic molecules and capture carbon through carbon fixation, primarily seen in some bacteria and archaea.

    • Photoautotrophs: Capture energy from sunlight and convert it into chemical energy through photosynthesis, using carbon dioxide as their carbon source, typically observed in plants and some bacteria.

    • Mixotrophs: Utilize a combination of organic and inorganic sources for energy and carbon, allowing them to adapt to fluctuating environmental conditions. An example of this versatility can be seen in certain species of protists that switch between autotrophic and heterotrophic modes depending on nutrient availability.

    • Heterotrophs: Rely exclusively on organic compounds for both energy and carbon, obtaining these essential nutrients through the consumption of other organisms, including animals, fungi, and most bacteria.

Cellular Organization

  • Organisms categorized by cell type:

    • Prokaryotes: Lack a nucleus and membrane-bound organelles.

    • Eukaryotes: Contain a nucleus and organelles (e.g., plants and animals).

Unicellular vs. Multicellular Organisms

  • Unicellular Organisms: Single-celled (e.g., most bacteria).

  • Multicellular Organisms: Composed of many cells with tissue specialization (e.g., plants, animals).

Viruses and Life Forms

  • Viruses consist of DNA or RNA within protein coats and must infect a host to reproduce.

  • They are considered acellular forms of life due to their dependency on host cells for propagation.