BIO 101 Cellular Respiration PDF

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Lecture Notes From Professor Addams...

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Cellular Respiration convert food into ATP, a universal source of energy for living organisms ● Life Requires energy ● ATP fuels work in cells ● MEtabolic pathways harvest energy from high energy molecules such as glucose ● The energy released is used to add a phosphate group to ADP ● Cells generally contain enough ATP to sustain from 30 seconds to a few minutes of activity A cellular respiration equation is helpful to show the changes in hydrogen atom distribution ● Glucose loses its hydrogen atoms and is ultimately converted to CO2 ● Loss of electrons is called oxidation What happens when Glucose is oxidized? ● When glucose is oxidized to carbon dioxide by burning, some energy is released as heat and light ● Oxygen atoms are reduced to form water ● In cells, glucose is oxidized through a long series of carefully controlled redox reactions ● The released free energy is used to synthesize ATP These reactions comprise cellular respiration Enzymes are necessary to oxidize glucose and other foods ● The enzyme that removes hydrogen from an organic molecule is called dehydrogenase ● Dehydrogenase requires a coenzyme called NAD+ (nicotinamide adenine dinucleotide) to shuttle electrons ● NAD+ can become reduced when it accepts electrons and oxidized when it gives them up Cellular Respiration ● Requires fuel. Oxygen, mitochondria ● Potential energy stored in chemical bonds of sugar, protein, and fat molecules ● Breaks bonds to release the high-energy electrons captured in ATP ● Oxygen is final electron acceptor ● Input: Oxygen _+ sugar output: carbon dioxide+water+ATP Three Step Process 1) Glcolysis 2) Krebs Cycle 3) ETC Cellular Respiration is a set of processes: ● Glycolysis- a six carbon glucose is broken down into two three-carbon pyruvate ● Pyruvate processing- Each pyruvate is oxidized to form acetyl CoA

● Citric acid cycle-Each acetyl CoA is oxidized to CO2 ● Electron transport and oxidative phosphorylationCatabolic Pathways ● Breakdown of molecules ● Often harvest stored chemical energy to produce ATP

Occurs in 3 main stages ● Stage 1: Glycolysis - Glycolysis begins respiration by breaking glucose, a six carbon molecule, into two molecules of a three-carbon compound called pyruvate (pyruvic acid) - This stage occurs in the cytoplasm Substrate-level phosphorylation: - Transfer of a phosphate group P from a substrate to ADP, producing ATP - Comes from cellular respiration Glycolysis: ● Each glucose molecule broken down into two molecules of pyruvate ● 2 ATP models produced ● 2 NADH molecules produced ● Glycolysis is the universal energy-harvesting process of living organisms - So, all cells can use glycolysis for the energy necessary for viability - The fact that glycolysis has such a widespread ● Stage 2: The Krebs Cycle - The citric acid cycle breaks down pyruvate into carbon dioxide and supplies the third stage with electrons - This stage occurs in the mitochondria - Aerobic respiration An overview of the citric acid cycle: Two carbons enter the cycle through acetyl CoA, and 2 CO2, 3 NADH, 1 FADH2, and 1 ATP exit the cycle. Cycle spins twice ● Step 3: Oxidate phosphorylation - During this stage, electrons are shuttled through the electron transport chain - As a result ATP is generated through oxidative phosphorylation associated with chemiosmosis - This stage occurs in the inner mitochondrial membrane...