How many decibels correspond to the lowest-intensity sound we can hear?
Mart 1 Lecture 13: Cellular Respiration: Harvesting Chemical Energy ● Catabolic pathways are the set of metabolic pathways that break down molecules into smaller units that are either oxidized to release energy, or used in other anabolic reactions. ○ Fermentation is the partial degradation of sugars in absence of oxygen. ■ Glycolysis generates two ATP whether oxygen is present ( aerobic) or not (anaerobic. ■ Alcohol fermentation consists of pyruvate being converted to ethanol. ■ Lactic acid fermentation consists of pyruvate reduced directly by NADH to form lactate. ○ Cellular respiration uses oxygen as a reactant to complete breakdown of organic molecules, this occurs in the mitochondria. ○ Carbohydrates, fats, and proteins are the three macromolecules used as fuel (in that order). ● ATP , adenosine triphosphate, is composed of adenosine and three phosphate groups that supplies energy for many biochemical cellular processes by undergoing enzymatic hydrolysis especially to ADP. ○ Phosphorylation is the transfer of the terminal phosphate group from ATP to another molecule. ● Redox reactions include the transfer of one or more electrons from one reactant to another. ○ Oxidation is the loss of electrons areduction is the addition of electrons (Oil Rig). ○ The electron transport chainis a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons across a membrane. ■ Electrons are passed by increasingly electronegative molecules in the chain until they are caught by oxygen, the most electronegative. ● Respiration occurs in three metabolic stages: glycolysis, Krebs cycle, and oxidative phosphorylation. ○ Oxidative phosphorylation is the metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP. ■ Substratelevel phosphorylation generates some ATP that can be found in glycolysis and Krebs cycle. ○ In Krebs cycle each cycle produces one ATP by substratelevel phosphorylation, three NADH, and one FADH₂ per acetyl CoA. ○ The inner mitochondrial membrane couples electron transport to ATP synthesis. Mart 2 ■ ATP synthase is an important enzyme that creates the energy storage molecule ATP.