Biology 1003 - Unit 1 Study Notes

Unit 1 - Introduction to Biology

1.1 Overview of Biology

  • Definition: Biology is the study of living organisms, encompassing their structure, function, growth, and interactions with their environments.

  • Key Focus for Course:

    • Human Biology

    • Microorganisms affecting human health

1.1 Branches of Biology

  • Anatomy: Study of physical structures within an organism.

  • Physiology: Study of the functions of living organisms and their parts.

  • Other Disciplines:

    • Cell Biology

    • Ecology

    • Immunology

    • Genetics

    • Microbiology

    • Histology

    • And more

1.2 Organization of Living Things

  • Taxonomy: Organisms can be categorized into three domains and six kingdoms:

    1. Domains:

    • Archaebacteria

    • Eubacteria

    • Eukarya

    1. Kingdoms (within Eukarya):

    • Protista

    • Fungi

    • Plants

    • Animals

  • Classification Criteria: Based on:

    • Cell structure (single-celled or multicellular)

    • Presence of nucleus (prokaryotic vs eukaryotic)

    • Environmental adaptation

    • Ability to move

    • Energy acquisition methods

    • Presence or absence of cell wall

Classification and Debate

  • Classification Changes:

    • Classification schemes are evolving with new discoveries.

    • Some biologists propose a seventh kingdom (Chromista) for all protists with chlorophyll.

1.2 Prokaryotic vs. Eukaryotic Organisms

  • Prokaryotic Organisms:

    • Basic characteristics:

    • Simple cell structure

    • No membrane-bound organelles

    • DNA located in the cytoplasm (no nucleus)

    • Include ribosomes and a cell wall

  • Eukaryotic Organisms:

    • Advanced characteristics:

    • Complex cell structure

    • Membrane-bound organelles (e.g., nuclei, mitochondria)

    • Larger cells with more DNA and complex genetic organization

    • Examples: Bacteria

Domains Overview

  • Domain Archaea:

    • Known for extreme living conditions (e.g., heat-loving, salt-loving, methane-producing)

  • Domain Eubacteria:

    • General characteristics:

    • Predominantly single-celled

    • Found in diverse environments

    • Mostly harmless or beneficial, but some pathogenic (e.g., tetanus, syphilis)

  • Notable Stones: Viruses are excluded from living organism classification.

1.2 Six Kingdoms

  1. Archaea

  2. Eubacteria

  3. Protists

  4. Fungi

  5. Plantae

  6. Animalia

1.2 Characteristics of Archaebacteria

  • Features:

    • Single-celled

    • Prokaryotic

    • Primitive, adapted to extreme environments

    • Examples: Thermophiles, halophiles, methanogens

1.2 Characteristics of Eubacteria

  • Features:

    • Mostly single-celled

    • Prokaryotic

    • Ubiquitous presence on Earth

    • Generally harmless or beneficial, some pathogenic: e.g., tuberculosis, pneumonia

  • Bacterial Diversity: ~500 species in the human gastrointestinal tract

1.2 Characteristics of Protists

  • Features:

    • Mostly single-celled

    • Eukaryotic

    • Some show characteristics akin to fungi (spores), plants (photosynthesis), or animals (motility)

    • Examples of disease-causing protists: Plasmodium (malaria), Giardia (diarrhea)

1.2 Characteristics of Fungi

  • Features:

    • Mostly multicellular (yeasts are exceptions)

    • Eukaryotic and non-photosynthetic

    • Include beneficial and poisonous varieties (e.g., mushrooms, mold)

1.2 Characteristics of Plants

  • Features:

    • Multicellular

    • Eukaryotic and photosynthetic

    • Can be terrestrial or aquatic

    • Examples: Ferns, trees, flowers, grasses

1.2 Characteristics of Animals

  • Features:

    • Multicellular

    • Eukaryotic and non-photosynthetic

    • Capable of locomotion

    • Examples: Worms, ants, goldfish, geckos, dogs

Review Questions

  • Identify characteristics by kingdom:

    • Photosynthetic eukaryotes → Plants

    • Eukaryotic, multicellular, non-photosynthetic → Fungi

    • Surviving extremophiles → Archaea

    • Multicellular non-photosynthetic with locomotion → Animals

1.6 Properties of Living Things

  • Common Characteristics:

  1. Composed of macromolecules

  2. Made of one or more cells

  3. Growth and metabolism

  4. Reproduction

  5. Genetic inheritance

  6. Evolution

  7. Homeostasis

1.6 Macromolecules

  • Basic elements: Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N)

  • Small Molecules: Sugars, amino acids, fatty acids, nucleotides

  • Macromolecule Types:

    • Polysaccharides (complex carbohydrates)

    • Proteins

    • Fats

    • Nucleic acids

1.6 Cellular Structure

  • Components:

    • All living organisms made of one or more cells

    • New cells arise from existing cells

    • Cells have membranes that separate internal and external environments

    • Single-celled organisms: e.g., bacteria, yeast.

    • Multicellular organisms: e.g., trees, Canada geese

1.6 Growth and Metabolism

  • Energy Usage: Organisms utilize energy for metabolism, movement, and growth

  • Source of Energy: Most energy originates from the sun and is processed by photosynthetic organisms, subsequently consumed by various faunal trophic levels

  • Metabolism: Represents energy transfer from one form to another, e.g., the conversion of glucose into ATP for movement

1.6 Reproduction

  • Definition: All organisms reproduce.

  • Types:

    • Cellular reproduction

    • Asexual reproduction (e.g., binary fission)

    • Sexual reproduction (mixing of DNA from two parents)

  • Reproductive Rates: Varies significantly across species

1.6 Heredity

  • Genetic Material: All organisms possess genetic material (DNA), which subdivides during the organism's division process.

    • Some entities like certain viruses utilize RNA

  • Gene Function: Genes dictate observable traits, while environmental factors may also influence these traits

1.6 Evolution

  • Definition: Populations genetically change over generations due to mutations

  • Human Example: Humans possess 46 chromosomes with variable gene expressions regarding traits such as pigmentation

1.6 Homeostasis

  • Definition: Organisms must maintain stability in their internal environments (e.g., blood pH, glucose levels, body temperature)

  • Feedback Mechanisms: Utilizes positive and negative feedback to maintain homeostasis

1.6 Homeostasis: Receptors

  • Types of Receptors:

    • Chemoreceptors: detect chemical concentrations

    • Osmoreceptors: detect osmolarity (water and ion concentrations)

    • Baroreceptors: detect blood pressure

    • Photoreceptors: detect light

    • Mechanoreceptors: detect stretching

    • Proprioceptors: detect body position

    • Nociceptors: detect pain

    • Thermoreceptors: detect temperature

1.6 Homeostasis: Negative Feedback

  • Mechanism: Restores systems back to their set point; diminishes stimuli leading to termination of response

  • Example:

    • Stimulus: Heat

    • Receptor: Thermoreceptors in skin

    • Integrating Center: Brain interprets heat as a stimulus

    • Effector: Sweat glands activate

    • Response: Sweating cools blood, reducing stimulation of thermoreceptors

1.6 Homeostasis: Positive Feedback

  • Mechanism: Amplifies the stimulus, creating an escalatory response, typically functional only in short bursts (unsustainable)

  • Example:

    • During inflammation, cells generate proteins that trigger further inflammatory responses.