Biology: Domains and Taxonomy Overview

Domains and Kingdoms

• Three domains of life: Bacteria, Archaea, and Eukarya
• Bacteria (Eubacteria)
• Archaea (Archaebacteria)
• Eukarya includes Plants, Animals, Fungi, and Protists.
• Six kingdoms: Plants, Animals, Fungi, Protists, Archaebacteria, and Eubacteria

Taxonomy

• Taxonomy is the classification of living organisms.
• Classification order (least to most specific): Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
• Species are determined by if different organisms can interbreed and produce fertile offspring

Human Taxonomy

• Domain: Eukaryota
• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Genus: Homo
• Species: Homo sapiens

Prokaryotes and Eukaryotes

• Prokaryotes (Bacteria, Archaea): Simple cells without membrane-bound organelles, lack a true nucleus.
• Eukaryotes (Eukarya): Complex cells with membrane-bound organelles, possess a true nucleus.

Cell Discovery

• Robert Hooke (1665): Observed cells in cork, coined the term "cell."
• Anton van Leeuwenhoek (1673): Created powerful microscope, observed microorganisms.
• Robert Brown (1827-1833): Discovered the nucleus.
• Matthias Schleiden (1838): Concluded plants are made of cells.

Spontaneous Generation

• Spontaneous generation: The incorrect idea that living things arise from non-living matter.
• Louis Pasteur: Disproved spontaneous generation through experiments; introduced pasteurization.

Cell Theory

• All living things are composed of one or more cells.
• Cells are the basic units of structure and function in living organisms.
• Cells come only from pre-existing cells.

Cell Parts

• Plasma/Cell Membrane: Membranous structure found in all cells (Prokaryotes and Eukaryotes).
• Cell Wall: Non-membranous structure found in some eukaryotes (Protists, Fungi, Plants) not animals
• Nucleus (True Nucleus): Membranous organelle found in all eukaryotes.
• Nucleolus: Non-membranous structure within the nucleus that produces ribosomes.
• Cytoplasm: All the material and organelles within the membrane, except the nucleus.
• Ribosomes: Non-membranous structures; site of protein synthesis in both prokaryotes and eukaryotes.
• Golgi Apparatus: Membranous organelle; involved in processing and packaging proteins and lipids.
• Endoplasmic Reticulum (ER): Membranous network; transports materials within the cell.
• Mitochondria: Membranous organelle; site of cellular respiration.
• Chloroplasts: Membranous organelle; site of photosynthesis in plants.
• Lysosomes: Membranous organelle containing enzymes for digestion; in animals, protists, and fungi.
• Peroxisomes: Membranous organelle; involved in metabolism.
• Vacuoles: Membranous sacs; involved in storage and transport.
• Cytoskeleton: Non-membranous network of protein filaments; provides structural support and facilitates movement.
• Centrioles: Non-membranous structures in animal and protist cells; involved in cell division.
• Genetic Material (DNA): Contains the instructions for building proteins and other cell components; wrapped around histone proteins.
• Chromatin: DNA in its loose, uncoiled state.
• Chromosomes: DNA tightly coiled around histone proteins, visible during cell division.
• DNA Structure: DNA wraps around 8 histone proteins to form a chromosome for organizing during cell division.

Organelles in Prokaryotic Cells

• All prokaryotic organelles are not bound by membranes, except the plasma membrane.

Cellular Components and Functions

• Cytoplasm: Contains enzymes for various chemical reactions; high water content.
• Nuclear Envelope: Double phospholipid bilayer surrounding the nucleus; has pores.
• Chromatin: Uncoiled DNA, found when the cell is not dividing.
• Chromosomes: Coiled DNA, for cell division.
• Ribosomes: Produced in the nucleolus, composed of ribosomal RNA and protein; responsible for protein synthesis.
• Microfilaments: Composed of actin; support, shape, and movement
• Microtubules: Composed of tubulin; part of the cytoskeleton and spindle apparatus.
• Spindle Apparatus: Made of microtubules; aids in cell division by separating homologous chromosomes.
• Centrioles: Composed of 9 triplet microtubules; part of the spindle apparatus.
• Cilia: Numerous, short hair-like projections for movement and filtering.
• Flagella: Few, long whip-like projections for movement.
• Lysosomes: Contains hydrolytic enzymes; involved in breaking down cellular components (programmed cell death).
• Cellular Respiration: Process of breaking down glucose to produce ATP.
• ATP (Adenosine Triphosphate): Energy currency of the cell; made of adenosine and three phosphate groups; generated in the mitochondria.
• Mitochondria: Inner and outer membranes; cristae (folds); contain their own DNA; involved in cellular respiration.

Explore the classification of living organisms through the three domains of life: Bacteria, Archaea, and Eukarya. Understand the hierarchy of taxonomy and how species are determined based on reproductive capabilities. This quiz also addresses the differences between prokaryotes and eukaryotes, as well as human classification.