Glycolosis Kreb’s Cycle Electron Transport Chain Cellular Respiration Glycolosis Kreb’s Cycle Electron Transport Chain

Terms to Know ATP (cellular energy molecule) is an unstable molecule that is used to activate most cell processes by losing a phosphate group. The phosphate group binds to most molecules to change their shape or “activate” the molecule. Reduced Carriers are molecules that store energy to be passed on later (2 types) NADH (high energy carrier) FADH2 (lower energy carrier)

ATP

Mitochondria Double membrane structure Interior space = Matrix (like cytoplasm) Site of Kreb’s Cycle Inner membrane space (between membranes) Site of electron transport chain Kreb’s Cycle = TCA Cycle = Citric Acid Cycle Oxidative phosphorization – movement of phosphate groups in the presence of Oxygen (Electron Transport Chain)

Overall Process Breakdown of glucose (or other sugar) into CO2 and H2O Requires Oxygen to complete the full process Net gain (per glucose + oxygen): 36 ATP, 6 CO2, 6 H2O Net gain (per glucose without oxygen) 2 ATP, 2 molecules of lactic acid (3C) Main process of creating energy is by concentration gradient across a membrane

Glycolosis Glucose (food) must enter the cell, this requires active transport (-2 ATP). The glucose moves across the membrane and into the cytoplasm This is where glycolosis occurs. Overall Process: Start: Glucose (6 carbons) Finish: Pyruvate x2 (3 carbons each) 2 NADH, 4 ATP (2 Net ATP)

Glycolosis Glucose has two phosphate groups added (one to each end) to energize the molecule which also allows it to cross the membrane. (-2 ATP) Glucose is then broken into two parts called glyceride 3-phosphate (3 carbons) One phosphate group is removed to produce NADH (reduced carrier) The 3 carbon molecules are then processed several times and the phosphate groups are removed to produce pyruvate and 2 ATP. (this occurs for each glyceride molecule)

Anaerobic Respiration Without oxygen Two Types Lactic acid production (occurs in most animals). When not enough oxygen is present, cells cannot complete the process of cellular respiration. Instead of producing CO2, the body produces lactic acid which can be broken back down into pyruvate when oxygen is present.

Fermentation The process of fermentation is a billion dollar industry ranging from alcoholic beverages to simple bread. Occurs in yeast and some bacteria. Instead of converting pyruvate to lactic acid, the pyruvate is broken down slightly, removing one carbon, to produce ethanol and CO2. Why does this cause the liquid (such as grapes) to become acidic?

Kreb’s Cycle Also called the Citric Acid Cycle Occurs in the matrix of the Mitochondria (interior region) Objective: to produce reduced carriers Start: Pyruvate (x2) and Oxaloacetate (4C) Finish: 3 CO2 + 4 NADH + 1 FADH2 + Oxaloacetate + 1 ATP

The Cycle Process is cyclic, meaning it always returns to the original materials so the process can occur many times. Pyruvate is converted to Acetyl-CoA by an enzyme which removes one carbon (CO2 produced) Acetyl-CoA (2C) is combined with Oxaloacetate (4C) to form Citric Acid (6C) Through a process of chemical reactions (exothermic) and enzymes Citric Acid is oxidized back to Oxaloacetate, releasing 2C (as CO2)

In the process of oxidation, energy is released and is picked up by reduced carriers 4 NAHD are produced (per pyruvate) 1 FADH2 is produced (per pyruvate) 1 ATP is produced (per pyruvate) The process is then ready to start all over, all the enzymes are recycled as well as staring products

NAD+ NADH CO2 FAD+ FADH2 CO2 NAD+ NADH ADP ATP NAD+ NADH CO2

Electron Transport Chain Final step in cellular respiration Focus is to synthesize ADP to become ATP Requires oxygen as final electron acceptor Occurs across the inner mitochondria membrane (inner membrane space + matrix) Starting materials: 10 NADH, 2 FADH2 Final products: 32 ATP, 6 H2O

Review Recall membrane transport Active transport across proteins Ions (charged) cannot cross the membrane There are 5 membrane bound proteins in the inner membrane, each with a higher electronegativity than the last (they attract electrons more) Hydrogen contains 1 proton (+) and 1 electron (-)

Process NADH attaches to the first transport protein. The H is removed and split, electrons are passed down the protein chain, while protons are pumped into the inner membrane space This electrons are passed from one protein to the next, causing more protons to be passed into the inner membrane space (3 from NADH, 1 from FADH2) Oxygen acts as the final electron acceptor, it has a higher electronegativity than the proteins

Final Steps All of the protons are trapped in the inner membrane space (high concentration) A protein channel (ATP Synthase) allows the protons to pass into the matrix (low concentration) by diffusion The energy created as the protons pass allows ADP to be phoshoralized into ATP (32 ATP) NADH = 3 ATP, FADH2 = 1 ATP