Diversity of Living Things

3.1 Introduction to Taxonomy

  • Taxonomy:
    • The science of classifying species.
  • Species:
    • A group of related organisms that can produce fertile offspring.
  • Humans classify things:
    • Aristotle (200 BC) attempted a classification system for over 500 animal species, categorizing them as air, land, and water dwellers.
  • Carl Linnaeus (1707 – 1778):
    • Swedish scientist, introduced a consistent way of grouping species based on morphological characteristics.
    • Established binomial nomenclature.
    • Considered the father of modern taxonomy.
  • Binomial Nomenclature:
    • Each organism has a genus and a species name.
      • Genus: taxonomic group of closely related species.
    • First name: Genus (Capitalized).
    • Second name: Species (lowercase).
    • Italics when typing, underline when writing by hand.
    • Example:
      • Homo sapiens or Homo sapiens
  • Living vs. Non-Living:
    • Living (Biotic):
      • Made of one or more cells.
      • Respond to stimuli.
      • Use chemicals to grow and reproduce.
      • Maintain stable internal conditions.
    • Non-Living (Abiotic):
      • Not made of cells.
      • Unable to respond to stimuli, grow, or reproduce.
  • Levels of Classification:
    • 8 taxa (taxon singular) used in classifying life.
    • Taxon: level of classification.
    • Most general taxon: domain.
    • Most specific taxon: species.
  • Taxonomic Hierarchy (General to Specific):
    • Domain
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family
    • Genus
    • Species
  • Taxonomists use various information to classify organisms:
    • Structural Information:
      • Skeletal structure, leaf anatomy, Gram positive/negative.
    • Behavioral Information:
      • Sounds, movements, social interactions.
    • Cytological Information:
      • Prokaryotic/eukaryotic, chromosome number.
    • Embryological Information:
      • Appearance in early development stages.
    • Physiological Information:
      • Biochemicals including DNA, RNA, and proteins.

3.2 Domains and Kingdoms

  • Determining How Species Are Related:
    • Scientists use 3 forms of evidence to determine species relationships:
      • Anatomical Evidence
      • Physiological Evidence
      • DNA Evidence
  • Anatomical Evidence:
    • Physical characteristics (size, shape, physical features).
    • Fossils.
    • Embryological development indicates shared ancestry.
  • Physiological Evidence:
    • Functioning of organisms, including proteins.
    • Genes determine the proteins a species makes.
    • Comparing proteins among species determines genetic similarity/difference.
  • DNA Evidence:
    • Similarities in nucleotide sequences.
    • Closely related species have similar DNA sequences.
    • Advances in technology have resulted in the reclassification of many species.
  • Phylogeny:
    • The science that deals with evolutionary relationships between species.
  • Phylogenetic Tree:
    • A way of showing evolutionary relationships.
  • Clades:
    • Taxonomic group with a single ancestor species and all descendants.
    • Node: Represents an ancestor species on the tree.
  • Structural Diversity:
    • Biological diversity seen in structural forms.
    • From internal cell structure to body morphology.
  • Taxonomic Ranks:
    • Kingdoms and domains highlight similarities and differences.
  • Timeline of Kingdoms:
    • 6 Kingdoms: Animals, Plants, Protists, Bacteria, Fungi, Archaea.
  • Domains:
    • Highest taxonomic rank, created after further analysis of Bacteria and Archaea.
    • 3 Domains:
      • Bacteria
      • Archaea
      • Eukarya
    • All 6 kingdoms belong to a Domain.
  • Main Characteristics of Kingdoms:
    • Classified by 5 main characteristics:
      1. Cell Type
        • Prokaryotic Cell: small, simple, no membrane-bound nucleus.
        • Eukaryotic Cell: larger, complex, with a membrane-bound nucleus.
      2. Number of Cells
        • Unicellular: one cell.
        • Multicellular: more than one cell.
      3. Cell Wall Material
        • Example: Peptidoglycan, Cellulose, Chitin, etc.
      4. Nutrition
        • Autotroph: makes its own food (usually sunlight).
        • Heterotroph: consumes other organisms for food.
      5. Primary Means of Reproduction
        • Asexual: offspring genetically identical.
        • Sexual: offspring are a hybrid of parents.

3.3 Identifying Organisms

  • Tools for Identification:
    • Smartphone Apps
    • Dichotomous Keys
    • Field Guides
  • Smartphone Apps:
    • Good choice when:
      • You have your phone and internet access.
      • You know of an app for the general type of organism (e.g., Shroomify for fungi, Merlin for bird songs).
  • Dichotomous Key:
    • A tool that uses a series of yes/no questions to guide you toward the identification of a particular organism.
  • Dichotomous Key:
    • Good choice when:
      • Your list of possible organisms is short.
      • You want to learn about small differences between organisms.
  • Field Guides:
    • Good choice when:
      • You have one for your local area (print or online).
      • You are looking to learn more about the organism.
  • Rules for Dichotomous Keys:
    • Always read both choices.
    • Understand the meaning of the terms.
    • When measurements are given, measure.
    • Consider that living things are always variable; use constant characteristics and make multiple observations.

3.4 Archaea & Bacteria

  • Domain Archaea:

    • Cell Type: Prokaryotic
    • Number of Cells: Unicellular
    • Nutrition: Heterotrophs (Uniquely Methanogenic) & Autotrophs
    • Cell Wall: Not made of peptidoglycan, sometimes no cell wall
    • Reproduction: Asexual → Binary Fission
    • Habitat: Extremophile (extreme environments)

  • Domain Bacteria:

    • Cell Type: Prokaryotic
    • Number of Cells: Unicellular
    • Nutrition: Heterotrophs & Autotrophs (Uniquely photosynthetic)
    • Cell Wall: Made of peptidoglycan
    • Reproduction: Asexual → Binary Fission
    • Habitat: Versatile mesophile (non-extreme) environment

  • Structure of Prokaryotes:

    • Cell wall: Provides structural support and protection.
    • DNA: A ring, not a strand (single chromosome).
    • Flagella: Used for movement.
    • Plasmid: Small loop of DNA (contains different genes than the chromosome).
      1. Cocci → spherical-shaped
      2. Bacilli → rod-shaped
      3. Spirilla → spiral-shaped

  • Prefixes to describe how they live

    • Mono- Live as single cells
    • Diplo- Live in pairs
    • Strepto- Live in linear chains
    • Staphylo- Live in clusters

  • Gram Staining:

    • Classifies and identifies prokaryotes.
      • Gram Positive: absorb purple stain, have a thick peptidoglycan layer.
      • Gram Negative: stain pink, have a thin peptidoglycan layer.

  • Nutrition:

    • Both Archaea and Bacteria can be autotrophic and/or heterotrophic.
    • Bacteria Only
      • Photosynthesis:
        • Some bacteria use this.
        • Sun converts CO2CO_2 into water and sugar, producing oxygen.
        • Cyanobacteria are best known.
    • Archaea Only
      • Methanogenesis (heterotrophic):
        • Unique to archaea.
        • Produces methane.

  • Reproduction:

    • Asexual by binary fission.

  • Bacteria: Endospores:

    • Survival Strategy unique to bacteria.
    • Create tough outer structure when conditions are unfavorable.

  • Habitats:

    • Bacteria and archaea live in environments with and without oxygen.
      • Most bacteria are mesophiles (moderate conditions).
      • Most archaea are extremophiles:
        • Thermophiles: heat-lovers.
        • Acidophiles: acid lovers.
        • Halophiles: salt-lovers.

  • Bacteria and Human Health:

    • Clostridium botulinum: can cause food poisoning.
    • Streptococcus pyogenes: causes strep throat.
    • Streptococcus mutans: causes tooth decay.

3.5 Fungi and Animals

  • Characteristics of Fungi

    • Domain: Eukarya
    • Cell Type: Eukaryotic
    • Number of Cells: Mostly Multicellular (Yeast = unicellular)
    • Nutrition: Heterotrophic → by Absorption
    • Cell Wall: Made of chitin (carbohydrate)
    • Reproduction: Asexual and/or Sexual (yeasts)

  • Structure of Fungi:

    • Hyphae: thread-like filament and makes complex structure inside
    • Mycelium: network of branching hyphae (increase surface area for absorbing nutrients)
    • Fruiting Body: the spore-producing reproductive structure.
    • Note: yeast is unicellular

  • Fungi Nutrition:

    • Absorb organic material from their environment.
    • Release digestive enzymes to breakdown molecules into smaller components, then absorb through cell walls.
    • Four Types of Nutrition:
    • Mutualistic fungi:
    • Parasitic
    • Predatory
    • Saprobial

  • Fungi Reproduction:

    • Produce spores that are carried by wind or water.
    • Spores in warm, moist environment with food produce new fungi.
    • Asexual: genetically identical spores (e.g., budding in yeast).
    • Sexual: hyphae of plus fungi fuse with hyphae of minus fungi; spores are genetic hybrids.

Characteristics of Animals:
* Domain: Eukarya
* Cell Type: Eukaryotic
* Number of Cells: Multicellular
* Nutrition: Heterotrophs
* Cell Wall: No Cell Wall
* Reproduction: Sexual

Animals characteristics:

  • Have the ability to move in at least one stages of their life

  • produce an embryo that undergoes stages of development

  • Body Plan of Animals:

    • Overall organization of an animal's body.
    • Characteristics used for classification:
      • Invertebrate vs. Vertebrate
      • Symmetry
      • Segmentation
      • Movement

  • Body Plan of Animals: Invertebrates vs. Vertebrates:

    • Invertebrate: no backbone.
    • Vertebrate: internal skeleton and backbone.

  • Body Plan of Animals: Symmetry:

    • Arrangement of organs or appendages.
    • Radial symmetry: divided into equal parts through a central point.
    • Bilateral symmetry: divided into 2 equal parts through a central point.

  • Body Plan of Animals:

  • Segmentation:

    • Division of the body into repetitive sections or segments.

  • Advantages of segmentation:

    • Effective movement.
    • If a single segment is damaged, the other segments can still function properly

Body Plan of Animals: Movement:

  • Two types of tissue exclusive to animals:
    • Nerve tissue
    • Muscle tissues

Animals:
Nervous system ranges from simple (nerve net) to complex (network of nerves, brain, spinal cord)

  • Invertebrate Animals: Sponges:

    • Sponges do not move as adults

  • Invertebrate Animals: Cnidarians:

    • Muscle tissue and simple nervous system (nerve net)
    • Radial symmetry
    • Two body forms:
    • Polyps: attach to surface and extend tentacles (stationary)
    • Medusas: swim and capture prey with stinging tentacles (e.g. Jellyfish)

  • Invertebrate Animals: Worms:

    • Bilateral Symmetry.
    • Has muscle tissue and simple nervous system

  • Invertebrate Animals: Arthropods:

    • Exoskeleton to protects the animal that move legs.

  • Vertebrate Animals:
    *All have Bilateral Symmetry:

  • Notochord:

    • Rod shaped structure the Spine is attached too

  • Nerve Cord:

    • Tube shaped cord present in embryo. Brain and spinal cord

  • Most distinctive features of mammals is:

    • 1. All have bodys covered in hair
    • 2. Mammary glands: glands that produce milk to feed the young

5.6 Kingdoms Plants and Protist

  • Plants
    • Domain: Eukarya
    • Cell Type: Eukaryotic
    • Multicellular
    • All are autotrophs
    • Sexual and Asexual
  • Four Types of Plants:
    • Non-Vascular
    • Seedless Vascular
    • Gymnosperms
    • Angiosperms
  • Protists
    • Domain Eukarya
    • Cell Type Eukaryotic
    • Number of Cells Most are unicellular Some are multicellular
    • Nutrition Autotrophs & Heterotrophs.
    • Cell Wall Cellulose in some - occasionally no cell wall.
    • Three Groups of Unicellular Protists

3.7 Viruses

  • Why We Care About Viruses

    • Prevention of disease
    • Vaccination
    • Genetic engineering

  • Familiar Viruses For Humans

    • Common cold
    • Smallpox
    • Cold sores / Herpes
    • Influenza (flu)
    • Hepatitis
    • Polio
    • Epstein Barr
    • Measles
    • Rabies
    • West Nile

  • NOT ALIVE!

    • Viruses don’t metabolize
    • Viruses can’t replicate on their own
    • Present as parasites in all organisms

  • Virus Morphology

    • Very very very small – 17 nm - 400 nm in diameter
    • 100 nm = smallest particle size that can fit through a surgical mask.

  • Virus Morphology

    • Viruses consist of:
      • DNA (or RNA) embedded in a protein coat (capsid)
      • Some viruses have an envelope surrounding the capsid
        • Envelope: a lipid membrane that is studded with proteins (spikes)

  • All life forms have associated viruses

  • Host Range: the range of organisms a virus is capable of infecting

  • Today viruses are much more likely classified in terms of the characteristics of morphology (how it looks) or infection physiology (how it infects), as well as host range