Chapter 9: Cellular Respiration

Cellular Respiration Living cells require Organisms use as their main energy source Cellular respiration is the process of Energy is released in the process of respiration when the cells of plants and animals

Respiration The breakdown of organic molecules is Aerobic respiration consumes Anaerobic respiration is similar to aerobic respiration but Fermentation is a

Cellular Respiration Cellular respiration includes both but is often used to refer to Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the :

Redox Reactions The during chemical reactions This released energy is used to Chemical reactions that transfer electrons between reactants are called In oxidation, a substance , or is In reduction, a substance , or is In cellular respiration, the

NAD+ In cellular respiration, glucose and other organic molecules are broken down in a series of steps As an electron acceptor, NAD+ functions as an Each NADH (the reduced form of NAD+) NADH passes the electrons to the

Electron Transport Chain Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction O2 pulls electrons The energy yielded is

Stages of Cellular Respiration Glycolysis - Anaerobic Citric Acid Cycle - Aerobic Oxidative phosphorylation - Aerobic

Mitochondria 1) Glycolysis 2) Citric Acid Cycle 3) Oxidative Phosphorylation (ETC)

Step 1: Glycolysis “Splitting of sugar” Breaks down glucose (C6H12O6) into Occurs in the NAD picks up H+ and electrons to form NADH2

STEP 1 - TWO Phosphates are attached to Glucose, forming a NEW Six-Carbon Compound.  The Phosphate Groups come From TWO ATP, which are Converted to ADP.     STEP 2 - The Six-Carbon Compound formed in Step 1 is SPLIT into TWO Three-Carbon Molecules of PGAL.     STEP 3 - The TWO PGAL Molecules are Oxidized, and each Receives a Phosphate Group Forming Two NEW Three-Carbon Compounds.  The Phosphate Groups are provided by Two molecules of NAD+ forming NADH.     STEP 4 - The Phosphate Groups added in Step 1 and Step 3 are Removed from the Three-Carbon Compounds.  This reaction produces Two molecules of Pyruvic Acid.  Each Phosphate Group is combines with a molecule of ADP to make a molecule of ATP.  Because a total of Four Phosphate Groups were Added, FOUR MOLECULES OF ATP ARE PRODUCED. TWO ATP Molecules were used in Step 1, but FOUR are Produced in Step 4.  Therefore, Glycolysis has a NET YIELD of TWO ATP Molecules for every Molecule of Glucose that is converted into Pyruvic Acid.  What happens to the Pyruvic Acid depends on the Type of Cell and on whether Oxygen is present

Glycolysis Summary Location: Reactants Products ** Simple Summary Summary total

Bridge Reaction In the presence of O2, Before the citric acid cycle can begin, In the mitochondria matrix… 1) Pyruvic Acid loses a C to form 2) The lost carbon 3)Acetic acid binds with The lost carbon binds with O2 making CO2

Step 2: The Kreb’s Cycle (Citric Acid Cycle) Takes place within the There are , each catalyzed by a specific enzyme The acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate The next seven steps

Step 2: The Kreb’s Cycle (Citric Acid Cycle) 2 molecules of CO2 are NAD+ and FAD (flavin adenine dinucleotide - another ion carrier) The NADH and FADH2 produced by the cycle relay electrons extracted from food The cycle generates Recall that two molecules of pyruvate are formed during glycolysis resulting in

Kreb’s Cycle Summary Products Reactants Location: Kreb’s Summary

Step 3: Electron Transport Chain (ETC) Takes place in the A series of molecules that excited electrons pass along, Most of the chain’s components are , which exist in

Step 3: Electron Transport Chain (ETC) Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of the energy extracted from food These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via The carriers alternate as they accept and donate electrons Electrons They are finally passed to O2 ,forming

NADH and FADH2 Dump the electrons and protons they’ve gathered throughout glycolysis and the citric acid cycle Again, O2 + 2e- + 2H+  H2O Electrons are passed through a number of proteins The chain’s function is to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts

Chemiosmosis ETC Summary Electron transfer in the ETC causes proteins to H+ then moves back across the membrane, passing through channels in ATP synthase uses the exergonic flow of H+ to drive This is an example of chemiosmosis, ETC Summary

ETC

ETC Summary Reactants Product Simpler ETC Summary Best ETC Summary Location: Reactants Product Simpler ETC Summary Best ETC Summary

Whole Respiration Process http://biology.clc.uc.edu/courses/bio104/atp.htm Song I Found...

Total ATP from 1 molecule of glucose in Total Energy Total ATP from 1 molecule of glucose in    Stage ATP + 4 Total Glycolysis (b/c 2 are used in the first step) CA Cycle ETC _________________ TOTAL   During cellular respiration, most energy flows in this sequence: Glucose -> NADH -> electron transport chain -> proton-motive force -> ATP

Fermentation Most cellular respiration requires Glycolysis can produce ATP , glycolysis couples with to produce ATP Fermentation uses instead of an electron transport chain to generate ATP 2 Types:

Lactic Acid Fermentation In lactic acid fermentation, Lactic acid fermentation by some fungi and bacteria is used Human muscle cells use lactic acid fermentation As the lactate is produced in the muscles it leaks out into the blood and is carried around the body. If this condition continues the functioning of the body will become impaired and the muscles will fatigue very quickly. This point is often measured as the lactic threshold or anaerobic threshold or onset of blood lactate accumulation (OBLA). When oxygen becomes available the lactic acid is converted to pyruvic acid and then into carbon dioxide, water and ATP. The process of lactic acid removal takes approx. one hour, but this can be accelerated by undertaking an appropriate warm down which ensures a rapid and continuous supply of oxygen to the muscles.

Lactic Acid Fermentation Example: Burning feeling in muscles during a workout From oxygen debt Lactate As the lactate is produced in the muscles it leaks out into the blood and is carried around the body. If this condition continues the functioning of the body will become impaired and the muscles will fatigue very quickly. This point is often measured as the lactic threshold or anaerobic threshold or onset of blood lactate accumulation (OBLA). When oxygen becomes available the lactic acid is converted to pyruvic acid and then into carbon dioxide, water and ATP. The process of lactic acid removal takes approx. one hour, but this can be accelerated by undertaking an appropriate warm down which ensures a rapid and continuous supply of oxygen to the muscles.

Alcohol Fermentation In alcohol fermentation, pyruvate is Bacteria and fungi (yeast) Alcohol fermentation by yeast is used in

Fermentation Obligate anaerobes carry out fermentation or anaerobic respiration and Yeast and many bacteria are facultative anaerobes, meaning that Review

Role of Macromolecules Catabolic pathways funnel electrons from many kinds of organic molecules into cellular respiration Glycolysis accepts a wide range of Amino groups can feed Fats are digested to Fatty acids are broken down by beta oxidation and yield An oxidized gram of produces more than twice as much ATP as an oxidized gram of

Regulation of Cell Respiration is the most common mechanism for control If ATP concentration begins to , respiration When there is of ATP, respiration Control of catabolism is based mainly on

Review Questions Define cellular respiration and state its importance as a life process. Differentiate between aerobic respiration, anaerobic respiration, and fermentation. State and explain the chemical equation for cellular respiration. Define oxidation and reduction and explain the idea of redox reactions. Explain the use of NAD+ as a coenzyme. Explain the electron transport chain (ETC). Name the 3 major stages of cell respiration, along with their locations. Explain glycolysis, stating the reactants, products, and major activities. Explain the bridge reaction, stating the reactants, products, and major activities. Explain the Kreb’s cycle, stating the reactants, products, and major activities. Explain the ETC, stating the reactants, products, and major activities. Explain the role of oxygen in the ETC. Define chemiosmosis and explain its role in cellular respiration. Differentiate between lactic acid fermentation and alcohol fermentation. Differentiate between oblicate anaerobes and facultative anaerobes. Explain the role of macromolecules in cellular respiration. Explain how cell respiration is regulated.