Cellular Respiration PDF

OBJECTIVES MELC’s Identify the stages of cellular respiration Describe the sequence of chemical processes Understand energy transfer in cellular respiration What is Cellular Respiration? is the process by which cells convert nutrients, primarily glucose, into energy (in the form of ATP)...

OBJECTIVES MELC’s Identify the stages of cellular respiration Describe the sequence of chemical processes Understand energy transfer in cellular respiration What is Cellular Respiration? is the process by which cells convert nutrients, primarily glucose, into energy (in the form of ATP) to power cellular functions. It takes place in the mitochondria of eukaryotic cells and involves a series of metabolic pathways, including glycolysis, the citric acid cycle (Krebs cycle), and the electron transport chain. C₆H₁₂O₆ + O₂ → CO₂ + H₂O + Energy C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy Glucose + oxygen → carbon dioxide + water + energy Mitochondria The Sites of Cellular Respiration Key Components Takes place in cytoplasm and mitochondria Produces ATP (Adenosine Triphosphate) Requires: ü Glucose (from carbohydrates) ü Oxygen (in aerobic respiration) Products: ü ATP (energy) ü Carbon dioxide ü Water Glucose Projections Fischer Projection Haworth Projection Ball and Stick Model Types of Cellular Respiration 1. Aerobic Respiration ØRequires oxygen ØOccurs in eukaryotic cells ØTakes place in mitochondria 2. Anaerobic Respiration ØNo oxygen required ØProduces less energy ØResults in fermentation Aerobic Respiration Requires oxygen Ø Generates large number of ATP Ø Two main phases: üKrebs cycle üElectron transport chain Key fact: This process makes mitochondria the "powerhouse of the cell" Aerobic Respiration ATP Production in Aerobic Respiration Total ATP Production: 10 NADH × 3 ATP = 30 ATP 2 FADH₂ × 2 ATP = 4 ATP 4 ATP from earlier stages Total theoretical yield: 38 ATP Actual yield: 36 ATP (2 ATP used for NADH transport) Anaerobic Respiration Occurs when oxygen is not present Combines with glycolysis Purpose: Converts NADH back to NAD+ Allows glycolysis to continue Produces steady ATP supply Types of Fermentation 1. Alcoholic Fermentation pyruvic acid + NADH → alcohol + CO₂ + NAD+ Used by yeast and some microorganisms Applications: Bread making (CO₂ causes dough to rise) Alcohol production Types of Fermentation 2. Lactic Acid Fermentation pyruvic acid + NADH → lactic acid + NAD+ Occurs in muscle cells during intense exercise Types of Fermentation 2. Lactic Acid Fermentation Effects: Causes muscle soreness Creates burning sensation Lactic Acid Fermentation Lack of oxygen: During intense exercise, muscles can use up oxygen faster than it’s supplied, limiting ATP production from aerobic respiration. Pyruvate from glycolysis: Without enough oxygen, cells rely on glycolysis to make ATP, producing pyruvate and NADH from glucose. Regeneration of NAD⁺: To keep glycolysis going, NAD⁺ needs to be regenerated. The enzyme lactate dehydrogenase converts pyruvate into lactic acid, which helps recycle NADH back to NAD⁺. Lactic acid buildup: Lactic acid builds up in muscles, causing a burning sensation. Later, it's taken to the liver to be converted back into glucose. Energy yield: Lactic acid fermentation produces only 2 ATP per glucose, much less than the 36-38 ATP from aerobic respiration, but it allows muscles to keep working without oxygen. Post-exercise: Once oxygen is restored, the body returns to aerobic respiration, and lactic acid is cleared from the muscles. Lactic Acid Fermentation Types of Fermentation 2. Lactic Acid Fermentation Applications in food production: Cheese and yogurt Pickles and kimchi Buttermilk and sour cream Fermentation in Food Production Key Microorganisms: Lactobacillus bacteria Ø Primary organism in lactic acid fermentation Ø Used in dairy products Ø Essential for kimchi production Fun fact: Kimchi fermentation involves both lactic acid and alcoholic fermentation due to different microorganisms naturally present on cabbage! STAGES OF CELLULAR RESPIRATION Stage 1: Glycolysis Occurs in cytoplasm Splits glucose into pyruvates Produces 2 ATP and 2 NADH Stage 2: Krebs Cycle Takes place in mitochondria Produces CO₂, ATP, NADH, and FADH₂ Stage 3: Electron Transport Chain Occurs in mitochondrial membrane Produces most ATP (up to 36 molecules) Glycolysis Glycolysis Glycolysis Kreb’s Cycle (Citric Acid Cycle) Kreb’s Cycle (Citric Acid Cycle) Kreb’s Cycle (Citric Acid Cycle) Kreb’s Cycle (Citric Acid Cycle) Kreb’s Cycle (Citric Acid Cycle) Oxidative Phosphorylation Stage 1: Electron Transport Chain Stage 2: Chemiosmosis Glycolysis and the Krebs Cycle are metabolic processes yielding 2 ATP net per glucose molecule. NADH and FADH2 molecules hold most of the extracted energy from organic compounds. Acquiring this energy requires the final stage of Cellular Respiration: Oxidative Phosphorylation. Oxidative Phosphorylation includes the Electron Transport Chain/System and Chemiosmosis. These processes occur in the inter-membrane space, inner membrane, and mitochondrial matrix of the mitochondria. Oxidative Phosphorylation Complex I - NADH Reductase or NADH Dehydrogenase- which converts NADH to NAD+. Complex II- Succinate Dehydrogenase- which converts Succinate to Fumarate, and also FADH2 to FAD. While Ubiquinone (Q) carries the electron gain in Complex I and activates complex II. Complex III -Cytochrome Reductase- the passage of electrons by Ubiquinone (Q) to Complex III drives the transport of four or more H+ ions across the inner membrane and activate Cytochrome C for complex IV. Complex IV- Cytochrome Oxidase- Cytochrome C clearances negative charge particles (electron) to the closing protein composite in the chain or system, Complex IV. Two hydrogen ions (H+) are propelled diagonally to interior membrane. The charge particles like hydrogen (H+) that handed from Complex IV move toward an oxygen (O2) molecule or atom, resulting for oxygen (O2) molecule to be divide. Simultaneously, oxygen (O2) atoms quickly grab hydrogen ions (H+) to produce two molecules of water (H2O). Oxidative Phosphorylation ATP Synthase Adenosine Triphosphate Generation complex (ATP synthase) transfers Hydrogen ions that were thrust out of the medium by the electron transport chain/system back into the medium. The energy starting the entry of protons into the medium is used to produce ATP by the phosphorylation (accumulation of a phosphate molecules) of Adenosine diphosphate (ADP). The drive of charge particles through the discerningly permeable mitochondrial membrane and down to their electrochemical gradient is called chemical osmosis (chemiosmosis). Electron Transport Chain Chemiosmosis