Unit 1 Biology: Biodiversity, Classification, and Micro-organisms Study Guide

Microscope Calculations and Magnification Formulas

• To determine the total magnification of a microscope:

  • $\text{Total magnification} = \text{Eyepiece mag} \times \text{Objective lens mag}$

• To determine the actual size of a specimen:

  • $\text{Actual size} = \frac{\text{Field Diameter (F.d)}}{\text{Fit \#}}$

• To determine the magnification of a drawing compared to its actual size:

  • $\text{Magnification of drawing} = \frac{\text{Diagram size}}{\text{Actual size}}$

• To calculate field diameter across different magnifications:

  • $\text{High mag} \times \text{High f.d} = \text{Low Mag} \times \text{Low f.d}$

Types of Biodiversity

• Species Diversity

  • Defined as the variety and abundance of species within a specific given area.

• Genetic Diversity

  • Defined as the variety of inherited genetic traits found within a single species.

  • Case Study/Example: The lack of genetic diversity in Tasmanian devils has led to their classification as an endangered population. Their genetic homogeneity makes them highly susceptible to contagious cancer.

• Ecosystem Diversity

  • Refers to the variety of ecosystems found on Earth, each of which contains many different species.

  • Conservation Importance: It is vital to conserve ecosystem diversity because every ecosystem supports its own unique species. A high number of different ecosystems increases overall global biodiversity.

• Ecosystem Services

  • These are the specific benefits experienced by organisms, including humans, provided by sustainable ecosystems.

  • Forest Examples: Forests absorb carbon dioxide from the atmosphere and maintain the fertility of the soil.

  • Wetland Examples: Wetlands act as water storage to reduce the impact of floods, filter water to remove pollutants, and provide critical habitats for commercially important species like fish and shellfish.

Definitions of a Species (Species Concepts)

• Morphological Species Concept

  • Description: Focuses on morphology, including size, shape, and other structural features.

  • Advantages: Its simplicity is its primary advantage; it considers the physical traits of individual organisms.

  • Disadvantages: Can be limited when individuals of the same species appear different or different species look similar.

• Biological Species Concept

  • Description: Focuses on the interbreeding ability of organisms to produce fertile offspring. To be considered the same species under this concept, they must produce fertile offspring after breeding.

  • Advantages: Wide use and general acceptance of the concept.

  • Disadvantages: It cannot be applied to organisms that use asexual reproduction or to fossil species (extinct species).

• Phylogenetic Species Concept

  • Description: Focuses on the evolutionary relationships among species and looks at what the organism evolved from. It utilizes DNA analysis and biochemical analysis.

  • Advantages: Because it uses DNA, it can be applied to extinct/fossil species.

  • Disadvantages: Not every organism has had its DNA or evolutionary history recorded yet.

Taxonomy and Classification Systems

• Taxonomy: The specific branch of biology dedicated to identifying, naming, and classifying species.

• Binomial Nomenclature

  • A system for assigning two-word Latin names to species.

  • The first word is the Genus.

  • The second word is the species.

  • Formatting Rules: Only the first letter of the Genus name is capitalized; the entire name must be written in italics.

• Taxonomic Classification Ranks (8 Ranks)

  • Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Evidence of Evolutionary Relationships

• Anatomical Evidence

  • Similarities in anatomical structures indicate a closer evolutionary relationship.

  • Example: Dinosaurs and Birds: These groups share more anatomical features than birds share with reptiles. Both dinosaurs and birds possess bones with large hollow spaces, whereas reptiles have dense bones. They also share similar bone arrangements in the hip, leg, and wrist.

  • Specific Fossil: Archaeopteryx fossils display a mix of dinosaur features and feathers.

• Homologous Structures: Structures from different species that are similar because of common ancestry.

• Physiological Evidence

  • Involves studying the order of amino acids in proteins and the overall protein structure.

• DNA Evidence

  • Derived from DNA analysis (nucleotide sequencing).

  • Scientists examine how similar the sequences of A, T, C, and G are between organisms.

  • Principle of Relatedness: More differences in amino acids correlate to more differences in DNA, which signifies that the organisms are less closely related.

• Phylogenetic Trees

  • A diagram showing evolutionary relationships. The closer the point where two animals meet on the tree, the more closely they are related.

Comparison of Prokaryotes and Eukaryotes

• Kingdoms

  • Prokaryotes: Bacteria and Archaea.

  • Eukaryotes: Protists, Plants, Fungi, Animals.

• Size

  • Prokaryotes: $1-10\,\mu m$.

  • Eukaryotes: $100-1000\,\mu m$.

• Genetic Material

  • Prokaryotes: Circular DNA, not bound by a membrane; the genome is typically made of a single chromosome.

  • Eukaryotes: DNA is located in a nucleus bounded by a membrane; the genome consists of several chromosomes.

• Cell Division and Reproduction

  • Prokaryotes: Division does not occur by mitosis or meiosis; asexual reproduction is the common method.

  • Eukaryotes: Division occurs by mitosis and meiosis; sexual reproduction is common.

• Number of Cells

  • Prokaryotes: Unicellular.

  • Eukaryotes: Multicellular.

• Organelles

  • Prokaryotes: Mitochondria and other membrane-bound organelles are absent.

  • Eukaryotes: Mitochondria and other membrane-bound organelles are present.

• Metabolism

  • Prokaryotes: Many are anaerobic (do not require oxygen for cellular respiration).

  • Eukaryotes: Many are aerobic (require oxygen for cellular respiration).

• Similarities: Both cell types possess a cell membrane, cytoplasm, DNA, and ribosomes.

Bacteria and Archaea Characteristics

• Bacterial Morphology (Shapes)

  • Cocci: Spherical shapes.

  • Bacillus: Rod shapes.

  • Spirillum: Spiral shapes.

• Bacterial Arrangements

  • Diplo: Found in pairs.

  • Strepto: Found in chains.

  • Staphylo: Found in clusters.

• Gram Staining Characteristics

  • Gram Positive Bacteria: Possess a thick outer peptidoglycan layer that absorbs stain easily, appearing purple.

  • Gram Negative Bacteria: Possess an outer lipopolysaccharide layer (a lipid/fat layer) that prevents stain absorption, appearing lighter or pink.

• Metabolism Comparison

  • Archaea: Can obtain energy through methanogenesis (found in the digestive tracts of animals).

  • Bacteria: Some are capable of photosynthesis, such as Cyanobacteria.

  • Both: Can be aerobic or anaerobic.

• Habitats

  • Archaea: Often extremophiles (living in extreme conditions).

  • Thermophile: Prefer extreme heat.

  • Acidophile: Prefer high acidity.

  • Halophile: Prefer high salt concentrations.

  • Bacteria: Mesophiles (living in moderate habitats).

Bacterial Reproduction and DNA Transfer

• Binary Fission (Similar to mitosis)

  1. The chromosome attaches to a point on the cell membrane.

  2. The chromosomes replicate.

  3. The cell membrane begins to lengthen, and the attachment points move apart.

  4. The cell membrane pinches inward.

  5. The daughter cells separate into two distinct organisms.

• Bacterial Conjugation

  • A method for the exchange of DNA.

  • A structures called a pilus is used to exchange a strand of plasmid DNA between bacteria.

Antibiotics and Resistance

• Mechanisms of Antibiotic Action (3 Ways)

  1. Stopping bacteria from building cell walls, which causes the cell to burst due to higher internal pressure.

  2. Preventing ribosomes from producing the proteins necessitated by the cells.

  3. Preventing cell reproduction by breaking DNA strands and stopping them from being repaired.

• Antibiotic Resistance (3 Ways)

  • Intrinsic Resistance: Natural resistance due to built-in features. For example, bacteria that lack cell walls are naturally unaffected by penicillin, which targets wall formation.

  • Acquired Resistance via Genetic Change: A DNA mutation alters a protein so the antibiotic can no longer bind or function, blocking the antibiotic's entry or action.

  • Acquired Resistance via DNA Transfer: Known as lateral gene transfer, bacteria share resistance genes with each other or obtain them from viruses called bacteriophages.

Protists and the Endosymbiotic Theory

• Endosymbiotic Theory: The theory that organelles such as mitochondria and chloroplasts were once individual prokaryotic organisms that were absorbed into a larger host cell, creating a mutually beneficial relationship.

• Evidence for Endosymbiosis

  • Membranes: Both mitochondria and chloroplasts have their own membranes; the inner membrane is similar to that of living protists.

  • Ribosomes: They have their own ribosomes, which are similar to those of protists but different from the ribosomes in the rest of the host cell.

  • DNA: Each organelle has its own circular DNA, similar to prokaryotic DNA.

  • Reproduction: They reproduce independently by binary fission like prokaryotes; the host eukaryote cannot create more of these organelles on its own.

• Types of Protists based on Nutrition

  1. Animal-like: Consumes other organisms for food. Examples include Cercozoans (Amoebas using pseudopods for feeding/movement) and Ciliates (Paramecium using cilia to move and guide food into the gullet).

  2. Fungus-like: Absorbs nutrients from other organisms; some may consume others.

  3. Plant-like: Perform photosynthesis (e.g., Euglenoids). They can also consume food if light is unavailable.

Fungi Characteristics and Nutrition

• Structure

  • Most are multicellular, though a few (like yeast) are unicellular.

  • Hyphae: Filament-like structures that serve as the basic structural unit.

  • Mycelium: A network of hyphae typically found underground.

  • Fruiting Body: The part found above ground, involved in spore formation.

• Modes of Nutrition

  • Parasitic: Absorbs nutrients from the living cells of a host.

  • Predatory: Soil fungi that capture prey using specialized mycelium.

  • Mutualistic: Form partnerships, such as mycorrhiza (mycelia increase a plant's root absorption while receiving sugars) or lichen.

  • Saprobic: Feed on dead organisms or organic waste.

Plant and Animal Kingdoms

• Plants

  • Characteristics: Eukaryotic, multicellular, with cell walls containing cellulose.

  • Autotrophs: Perform photosynthesis for food; can reproduce sexually.

• Animals

  • Characteristics: Eukaryotic, multicellular, no cell walls, heterotrophs (ingest then digest food), mobile at some stage in life, reproduce sexually.

  • Types of Symmetry: None, Radial, or Bilateral.

  • Classification Characteristics:

  • Levels of organization (tissues, organs, systems).

  • Body layers in embryos: Ectoderm (outer), Mesoderm (middle), Endoderm (inner).

  • Body cavities: Some have a coelom (fluid-filled cavity) to allow complex organ development.

  • Segmentation: Divided body parts.

  • Movement: Enabled by nerve and muscle tissue; some adults are sessile (stationary).

  • Backbone: Invertebrates (no backbone) vs. Vertebrates (backbone present).

Viruses

• Nature of Viruses: Non-cellular; they have no organelles, no metabolism, and cannot live independently. They are dependent on the internal workings of host cells.

• Specificity: Viruses infect specific species and specific cell types (e.g., HIV infects Helper T-cells; Rhinovirus infects respiratory cells).

• Structure: Composed of two main parts: a Capsid (protein coat) and Nucleic Acid (DNA or RNA).

• Viral Life Cycles

  • Lytic Cycle:

  1. Virus attaches to the cell wall and injects nucleic acid.

  2. Virus replicates inside the cell.

  3. The cell eventually bursts (lyses) due to the high volume of viruses.

  4. New viruses are released to infect more cells.

  • Lysogenic Cycle:

  1. Virus attaches and injects nucleic acid.

  2. Viral genetic material blends with the host cell's genetic material.

  3. The host cell replicates, copying the viral DNA along with its own.

  4. Viral DNA stays dormant until an external factor triggers it to start creating new viruses (entering the lytic cycle).