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Systematic Biology

• Systematic biology is the science of describing, identifying, naming, and classifying organisms.
• Taxonomical classification: grouping and ranking organisms with common features into groups.

Historical Evolution of Classification

• Ancient Greek scientists like Theophrastus established early systems.
• Scientists like Carl Linnaeus developed the 2-kingdom system (plants and animals).
• Later, the 3-kingdom system arose including plants, animals and protista, and more recently the 5-kingdom system (monera, protista, fungi, plantae, and animalia).
• Modern systems use genetic analyses for more accurate classifications.

Eukaryotic vs. Prokaryotic Cellular Organization

• Prokaryotes lack a nucleus and membrane-bound organelles.
• Examples are bacteria.
• Eukaryotes have a nucleus and membrane-bound organelles.
• Examples are animals and plants.

Three-Domain System

• Classifies organisms into three domains (bacteria, archaea, and eukarya) based on genetic analyses.
• This is a more recent and a higher level of classification than kingdoms.
• It is a significant advancement because it focuses on the evolutionary relationships between organisms.

Binomial Nomenclature

• A system for naming organisms using two Latin or Latinized names.
• The first name represents the genus and the second name designates the species.
• For example: Homo sapiens.

Virus Structure and Life Cycle

• Viruses are subcellular entities and are considered non-living entities until they infect a host cell.
• Fundamental components include a genome (DNA or RNA) enclosed in a protein capsid.
• Some viruses have an additional envelope.
• Viruses reproduce using the host cell's machinery.
• There are two main viral life cycles; lytic and lysogenic.

Bacterial Morphology and Structure

• Bacteria are classified by their shape (cocci, bacilli, or spiral).
• Bacteria all have a cell wall, and some have a capsule.
• Bacteria have a single, circular chromosome.
• Gram-positive bacteria have a thick cell wall, while gram-negative bacteria have two cell membranes.

Bacterial Reproduction and Genetics

• Bacteria commonly reproduce asexually by binary fission where one cell divides into two.
• Mechanisms of gene transfer include conjugation, transduction, and transformation.

Cyanobacteria (Blue-Green Algae)

• Cyanobacteria are prokaryotic organisms that carry out photosynthesis.
• They have chlorophyll a as well as phycobilins (phycocyanin and phycoerythrin).
• They can exist as unicellular organisms, colonies, or filaments.
• They play a significant role in nitrogen fixation and photosynthesis.