Biological and Morphological Species Concepts

Taxonomy

• Classifying living things involves 8 characteristics: made of cells, reproduce, need and use energy, grow and develop, respond to stimuli, move, exchange gases, and excrete waste.
• Classifying is important for identifying species, farming practices, medical disease identification, treatment, invasive species control, conservation biology, and global communication about species.
• Morphological Species Concept focuses on the physical characteristics (morphology) of organisms like body size and shape to determine species similarity.
• Advantages of morphological species concept: simple.
• Disadvantages: Populations can have non-identical individuals.
• Biological Species Concept defines a species based on organisms capable of interbreeding naturally and producing viable offspring.
• Organisms might appear similar but be different species.
• Advantages: Easy to determine if similar organisms are the same species.
• Disadvantages: Not applicable to all species. Doesn't apply to extinct species or asexually reproducing species.

Phylogenetic Species Concept

• Focuses on evolutionary relationships among organisms.
• A species is a distinct cluster of organisms from other clusters showcasing relationships among organisms.
• Advantage: Can be applied to extinct species and uses modern DNA analysis.
• Disadvantage: Evolutionary history is not always known for all species.

Naming Species

• A standardized system (binomial nomenclature) is essential for naming species universally.
• This system uses a two-part Latin name.
• First part: Genus (capitalized). Second part: Species (lowercase).
• Both parts are written in italics when typed and underlined when handwritten.

Classifying Species

• Species concepts help determine what species are.
• Binomial nomenclature creates official species names.
• Classification groups organisms based on criteria, revealing evolutionary relationships.
• Hierarchical classification - from most general categories to most specific.

Taxonomic Categories

• Organisms are grouped in nested categories (e.g., species, genus, family).
• Specific, numbered ranks (levels) and specific taxa (names) are included in taxonomy.

Bacteria

• Cell Wall Structure
• Gram positive: two layers (lipid, peptidoglycan). Gram negative: three layers (lipid, peptidoglycan, lipopolysaccharide).
• Obtaining Nutrients: Autotrophs (make their own organic compounds from CO2) and heterotrophs (obtain energy by breaking down organic molecules from their environment).
• Respiration (energy creation): Aerobic respiration (requires oxygen), anaerobic respiration (does not require oxygen), and facultative anaerobes (can survive with or without oxygen).

Characteristics of Bacteria

• Mostly single-celled.
• No nucleus or membrane-bound organelles.
• Cell walls.
• Circular chromosomes.
• Reproduce asexually or sexually.
• Prokaryotic.
• Anaerobic or aerobic.
• Heterotrophic or Autotrophic.
• Structure: Very small.

Bacteria Contain

• Cell Wall (support and protect cell).
• Cell membrane (controls what enters/exits cell).
• Ribosomes (formation of proteins).
• DNA (single strand in a ring shape).
• Some contain flagella (movement).

Bacteria cell shapes

• Spherical (Coccus).
• Rod-shaped (Bacillus).
• Spiral (Spirillum).

Bacteria Diseases

• Coccus (e.g., Streptococci, Staphylococcus).
• Bacilli (e.g., E. Coli).
• Spirochetes (e.g., Borrelia burgdorferi).

Gram Stain

• Classifies bacteria based on their reaction to a crystal violet/iodine dye.
• Gram-positive bacteria retain the violet stain; Gram-negative bacteria appear pink.

Viruses

• Obligate intracellular parasites (must reproduce inside a host cell).
• Possess genetic material (DNA or RNA), but lack cellular structure.
• Viral Structure: Genetic Material (DNA or RNA) - encased in a protein coat (capsid). Some have lipid envelope.
• Classifying: Size and shape of capsid. Some also classified based on diseases they cause.
• Reproduction: Lytic cycle (replication and destruction of host cell) Lysogenic (replication but does not destroy host cell - the viral DNA becomes part of the host - called the provirus/prophage)
• Virus Differences: Lytic destroys the host cell, Lysogenic does not.

Retroviruses

• These viruses use reverse transcriptase to convert RNA into DNA, which then incorporates into the host cell's DNA.
• Retroviruses use reverse transcriptase to convert RNA into DNA which then incorporates into the host's DNA - making a viral provirus.

Herpes Viruses

• Viral disease causing cold sores, which can appear and disappear throughout a lifetime.
• Recurring infections, because the virus is in a latent form. It stays dormant in the host's body, within the nerve cells, until activated.

Prions

• Infectious proteins that cause diseases by altering normal proteins into abnormal shapes.
• Non-genetic diseases.
• Lack DNA and RNA.
• Usually affect the central nervous system of animals.

Protists

• Eukaryotic organisms (possess a nucleus and other membrane-bound organelles)
• Primarily unicellular, although some are multicellular.
• Diverse groups, difficult to clearly classify into only one category

Animal-like protists (protozoans)

• Heterotrophic (consuming other microorganisms or organic matter for energy and nutrients).
• Classified into 4 main phyla: Cercozoa, Ciliophora, Zoomastigina, and Sporozoa.
• Some species are parasites; others are free-living, not dependent on another organism.

Fungus-like protists

• Obtain nutrition from dead organisms or non-living matter.
• Divided into 3 main groups: plasmodial slime molds, cellular slime molds, and water molds.
• Typically live in moist environments and produce spores.

Plant-like protists (algae)

• Autotrophs (carry out photosynthesis)
• Essential for primary production in aquatic ecosystems.
• Divided into different groups based on their pigment composition and other characteristics.

Diatoms

• Unicellular algae with silical walls.
• Important component of phytoplankton.

Dinoflagellates

• Unicellular algae with two flagella.
• Some species produce toxins that cause "red tides."

Euglenoids

• Unicellular and can be autotrophic (using photosynthesis) or heterotrophic (consuming other organisms).
• Presence of a flagellum.

Paramecium

• Are ciliates.
• Covered with cilia(hair-like projections).
• Important in aquatic ecosystems.

Water molds

• Filamentous, can be parasitic to plants and animals..
• Important decomposers of organic material in freshwater ecosystems.

Zoomastigina

• Possess flagella for movement.
• Many species live freely, and some are parasitic.

Sporozoans

• Non-motile.
• Characterized by their complex life cycles, often involving vectors.
• Malaria is a disease caused by some sporozoans.

Viruses (cont.)

• Viral Replication: Lytic cycle (destroys host cells or lysogenic cycle (does not destroy host cell - integrated into DNA, can be dormant).
• Virus Classifications: DNA, or RNA.

Application of Viruses

• Biological research
• Treating bacterial diseases.
• Biological insecticides.