Cellular respiration converts foodstuffs' chemical energy into ATP for cellular processes. Oxygen-dependent organisms use cellular respiration, anaerobic organisms use fermentation. Mitochondria contain enzymes for respiration in eukaryotic cells
Electron transport chain is third step of aerobic cellular respiration. Located in mitochondria's inner membrane, generating most cellular energy. Oxygen required for chain termination with electron donation to oxygen
Unicellular organisms consist of a single cell, unlike multicellular ones. Most prokaryotes are unicellular, including bacteria and archaea. Unicellular organisms are thought to be the oldest form of life. Early protocells emerged 3.5-4.1 billion years ago
Organelle is a specialized subunit within a cell with specific function. Organelles can be membrane-bound or non-membrane-bound structures. Some structures extending outside cells are also considered organelles
ETC transfers electrons between donors and acceptors via redox reactions. Process couples electron transfer with proton movement across membranes. Energy from redox reactions drives ATP synthesis through electrochemical gradient
Ribosomes are macromolecular machines found in all cells for protein synthesis. Consists of small (30S) and large (50S) subunits containing rRNA and proteins. First observed by George Palade in 1950s as dense particles