Classification of Living Things

Classification of Living Things

• Life is the broadest category in the classification of living things
• The subsequent categories are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species

Kingdom Animalia Example: Blue Whale

• Phylum: Chordata
• Class: Mammalia
• Order: Cetacea
• Family: Balaenopteridae
• Genus: Balaenoptera
• Species: musculus

Kingdom Animalia Example: Tilapia

• Phylum: Chordata
• Class: Actinopterygii
• Order: Cichliformes
• Family: Cichlidae
• Genus: Tilapia
• Species: sparrmani

Kingdom Animalia Example: Duck

• Phylum: Chordata
• Class: Aves
• Order: Anseriformes
• Family: Anatidae
• Genus: Anas
• Species: platyrhynchos

Kingdom Animalia Example: Housefly

• Phylum: Arthropoda
• Class: Insecta
• Order: Diptera
• Family: Muscidae
• Genus: Musca
• Species: domestica

Kingdom Animalia Example: Gorilla

• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Genus: Gorilla
• Species: gorilla

Kingdom Animalia Example: Human

• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Genus: Homo
• Species: sapiens

Phylum Chordata

• Includes animals with a flexible rod supporting their dorsal or back sides

Class Mammalia

• Characterized by milk-producing mammary glands for feeding their young
• Characterized by a neocortex region of the brain
• Characterized by fur or hair
• Characterized by sweat and oil glands on the skin

Phylum Arthropoda

• Includes a wide diversity of animals with hard exoskeletons and jointed appendages

Class Insecta

• Includes animals that have segmented bodies, jointed legs, and external skeletons (exoskeletons)

Domains

• The three domains are: Eukarya, Animalia and Chordata
• These are broken down into Class Mammalia, Order Primates, Family Hominidae, Genus Homo
• The final breakdown is into Species Homo sapien

Biological Classification

• Provides meaningful groupings of organisms based on evolutionary relationships, similarities, and differences

Methods to Determine Organism Relatedness

• Fossil records are helpful
• Comparative homologies provide Similarity of anatomy/physiology due to shared ancestry
• Comparative sequencing of genetic material (DNA & RNA)

Classification Factors

• Presence of a nucleus is a factor
• Single-celled or multicellular bodies can define the category
• How the organism creates food
• The organization of the body, including photosynthesis, body plans, and specialized organs

Three Domains of Life

• Eubacteria: This is a domain of true bacteria that are prokaryotes and possess peptidoglycan in their cell walls; the examples are Streptococcus pneumoniae and Escherichia coli.
• Archaea: These were once thought of as bacteria however their cell walls lack peptidoglycan.
• Eukaryota: These are all eukaryotic organisms and fall into 4 Kingdoms.
• Protista, examples include algae
• Fungi, examples include mushroom
• Plantae, examples include maple tree
• Animalia, examples include humans

Eukaryotes

• Eukaryotes contain an organism that has a nucleus within cells
• Eukaryotes includes plants, animals, and fungi

Classification by Kingdom

• The levels are: Monera, Protista, Fungi, Plantae, and Animalia

Kingdom Monera

• Includes archaebacteria and eubacteria
• These are unicellular prokaryotes
• They lack a true nucleus
• They can be heterotrophic or autotrophic
• They are microscopic and exist everywhere
• They have a cell wall of amino acids and polysaccharides (peptidoglycan for bacteria)
• Heterotrophic bacteria are parasitic or saprophytic
• Autotrophic bacteria can be chemosynthetic or photosynthetic
• Includes bacteria and cyanobacteria

Types of Bacteria Shapes

• Coccus bacteria are spherical
• Bacillus bacteria are rod-shaped
• Vibrium are comma-shaped
• Spirillum bacteria are spiral-shaped

Kingdom Protista

• Includes unicellular, eukaryotic organisms
• Exhibits autotrophic or heterotrophic nutrition
• Moves via pseudopodia, cilia, or flagella
• e.g., Amoeba, paramaecium

Subgroups within Protista

• Chrysophytes: Golden algae (desmids) and diatoms that are found in marine and freshwater habitats.
• Dinoflagellates: Photosynthetic and marine organisms. Their color relies on key pigments (red, blue, brown, green, or yellow).
• Euglenoids: Live in freshwater and have a protein-rich layer called a pellicle instead of a cell wall. Slime Moulds: Saprophytes that move along putrefying leaves and twigs and nourish themselves on organic material. In favorable surroundings they form Plasmodial slime molds.
• Protozoans: Heterotrophs that survive as parasites or predators.

Kingdom Fungi

• Includes multicellular, eukaryotic organisms
• Exhibits a saprophytic mode of nutrition
• Includes slender, long, thread-like constructions called hyphae, which form a web called mycelium
• Forms hyphae with cross-walls or septae
• The cell wall is composed of chitin
• Most fungi are saprophytes and are heterotrophic eg., Yeast, Aspergillus, and Mushrooms

Kingdom Plantae

• Includes multicellular, eukaryotic organisms
• The cell wall is made of cellulose
• Creates its own food through photosynthesis
• Subdivided into Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms.
• Examples include Pines, ferns, and Mango trees

Kingdom Animalia traits

• Multicellular, eukaryotic organisms without cell walls
• All are heterotrophs
• Includes organisms from simple to complex
• Genetically diverse
• Exhibits an organ-system level of organization.
• Examples are Earthworms and Hydra

Binomial Nomenclature System

• Naming system first proposed in the 1700s by Carolus Linnaeus.

Three Rules for Binomial Nomenclature

• Each organism has two Latinized names: a generic name (genus) and a specific name (species). Genus names are always capitalized
• Species names are lower case
• Genus and species names are always italicized or underlined when written.

Cell Structure: Nucleus

• Contains DNA, which controls cell activities
• Contains base sequences ("instructions") to make proteins
• DNA associates with histone proteins and becomes chromatin (wound into chromosomes)

Cell Structure: Plasma membrane

• Consists of a phospholipid bilayer with proteins
• Contains cholesterol to regulate membrane fluidity
• Contains cell contents, holds the cell together, and controls substance movement in/out of the cell

Cell Organelles: Mitochondria

• Site of ATP production during aerobic respiration Self-replicating, making them numerous in cells with high energy requirements
• Contains a double membrane with folds called cristae for a large surface area for respiration

Cell Organelles: Chloroplasts

• Site of photosynthesis enclosed by a double membrane
• Contains internal thylakoid membranes arranged to form grana (linked by lamellae)
• These structures are found in plants only and certain types of photosynthesizing bacteria or protoctists.

Cell Organelles: Cell wall

• Rigid structure for cell support
• Composed of cellulose (in plants), chitin (in fungi), and murein (in prokaryotes)

Cell Organelles: Rough endoplasmic reticulum (RER)

• Extension of the nuclear envelope coated with ribosomes
• Facilitates protein synthesis by providing a large surface area for ribosomes
• Transports newly synthesised proteins to the Golgi apparatus for modification

Cell Organelles: Golgi apparatus

• Fluid-filled membrane-bound flattened sacs surrounded by vesicles
• Receives proteins from the RER and lipids from the SER
• Modifies proteins and lipids and repackages them into vesicles
• Also the site of lysosome synthesis