Cellular Respiration Chapter 7 Miss Colabelli Biology CPA

Cellular Respiration Complex process that our cells make ATP by breaking down organic compounds Organisms that use cellular respiration are known as heterotrophs

Cellular Respiration Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen C6H12O6 + 6O2 6CO2 + 6H2O + ATP Same equation for photosynthesis JUST BACKWARDS!

Glycolysis Process where one molecule of glucose is broken in half, producing two 3-carbon molecules of pyruvic acid Creates a small amount of ATP and NADH Process is anaerobic Does not require oxygen

Aerobic Respiration If oxygen is present in cell environment Pyruvic acid is broken down to make a large amount of ATP If no oxygen is available for the pyruvic acid Fermentation

Fermentation Releases energy from pyruvic acid without oxygen Two types Lactic Acid Alcoholic

Lactic Acid Fermentation Lactic Acid is produced by muscles during rapid exercise when the body cannot supply enough oxygen http://www.youtube.com/watch?v=K_JFBxRBe9Q http://www.youtube.com/watch?v=rGaP9nE8d9k http://www.youtube.com/watch?v=X-ZZETT6F-s

Alcoholic Fermentation Alcoholic fermentation is done by yeasts and some microorganisms Produces an alcohol & Carbon dioxide

Glycolysis Glucose  2 pyruvic acid molecules Step 1: Glucose molecule uses two ATP molecules to make a 6-carbon molecule with two phosphates

Glycolysis Step 2: Glucose molecule breaks in half to make two G3P molecules

Glycolysis Step 3: Each G3P molecule gets a phosphate added and 2 NAD+ are reduced and gain an electron to become NADH

Glycolysis Step 4: Each 3-Carbon molecule loses their phosphates to make 4 molecules of ATP, 2 molecules of water, and 2 molecules of pyruvic acid

Fermentation Anaerobic process after glycolysis Pyruvic acid is used to become either lactic acid or ethyl alcohol This process is important because it regenerates NAD+ molecules for glycolysis to continue to work

Lactic Acid Fermentation Pyruvic acid  lactic acid NADH  NAD+ Important for making dairy products Produces certain cheeses and yogurts Occurs naturally in your muscles when you work out Muscle soreness

Lactic Acid Fermentation Muscles use up all available oxygen Switch to anaerobic respiration Increases acid levels in muscles causing the fatigue Eventually gets processed in liver back to pyruvic acid

Lactic Acid Fermentation

Alcoholic Fermentation Pyruvic acid  ethyl alcohol NADH  NAD+ Ethyl alcohol is a 2-carbon molecule Pyruvic acid loses a carbon by releasing CO2

Alcoholic Fermentation Yeast needs to get food to survive such as sugars from fruit Yeast breaks down to ferment the pyruvic acid into ethyl alcohol and CO2 If CO2 is released, you get regular alcohol Ex: wine If CO2 is not released, you get sparkling alcohol Ex: Champagne

Efficiency of Glycolysis Glycolysis uses 2 ATP in order to create G3P molecules Makes 4 ATP at the end of the process As a process to make energy, the efficiency is about 2% Very low for necessary energy This is why we need cellular respiration!! http://www.youtube.com/watch?v=00jbG_cfGuQ

The Krebs Cycle During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions Citric Acid is created in this cycle thus giving it the nickname Citric Acid cycle Net ATP Production is 2 ATP

Electron Transport Chain The electron transport chain uses the high- energy electrons from the Krebs Cycle to convert ADP to ATP Total ATP produced: 32

Aerobic Respiration Only occur in the presence of oxygen Two stages Krebs Cycle Electron Transport Chain with chemiosmosis Prokaryotes Occur in cytosol Eukaryotes Occur in mitochondria

Aerobic Respiration After glycolysis, pyruvic acids are produced Pyruvic acid moves inside mitochondria into mitochondrial matrix (space between two membranes) Pyruvic acid + CoA  Acetyl CoA + CO2

The Krebs Cycle Acetyl CoA  CO2 + H + ATP The H produced reduce NAD+  NADH Five steps in the Krebs Cycle Occurs in mitochondrial matrix Citric Acid is made in Step 1 therefore this is also called the Citric Acid cycle Net ATP produced is 2 ATP

Krebs Cycle - Step 1 Acetyl CoA + oxaloacetic acid  Citric Acid This step releases CoA back into the mitochondrial matrix for pyruvic acid to be fixed again

Krebs Cycle – Step 2 Citric acid releases CO2 and H Becomes a 5-carbon compound The H released, reduces the NAD+ to NADH

Krebs Cycle – Step 3 Five carbon compound releases another CO2 and H Becomes a 4-Carbon compound Another NAD+ is reduced to NADH Produces an ATP

Krebs Cycle – Step 4 4 carbon compound releases H atom This time, FAD is reduced to FADH2 Similar molecule to NAD+

Krebs Cycle – Step 5 4-Carbon compound releases H atom Reduces NAD+ to NADH This reaction regenerates initial oxaloacetic acid http://www.youtube.com/watch?v=JPCs5pn7UNI

Don’t let this happen to YOU!

Electron Transport Chain Uses the high-energy electrons from the Krebs Cycle to convert ADP to ATP Total net ATP produced is 34!! Prokaryotes Occurs on cell membrane of organism Eukaryotes Occurs in the mitochondria membrane called cristae

ETC – Step 1 NADH & FADH2 are used to power this chain of reactions NADH & FADH2 are oxidized (lose electrons) to the electron transport chain Also donate H atoms NADH  NAD+ FADH2  FAD+

ETC – Step 2 Electrons from NADH & FADH2 are passed down chain Lose some energy each time passed on

ETC – Step 3 Lost energy from electrons transferring down the chain pump protons (H+) This creates high concentration of H+ between inner and outer membranes Creates a concentration gradient & electrical gradient since H+ are positive

ETC – Step 4 Concentration & electrical gradients in membranes produce ATP molecules by chemiosmosis ATP synthase is protein embedded in membrane that pumps protons out and creates ATP

ETC – Step 5 The electrons move to final acceptor down the chain Oxygen is the final acceptor Oxygen also accepts protons provided by NADH & FADH2 The protons, electrons, and oxygen all combine to produce H2O

Importance of Oxygen The only way to produce ATP is by the movement of electrons in the ETC Oxygen is the final acceptor Without oxygen, the ETC would halt

Efficiency of Cellular Respiration Glycolysis 2 ATP Krebs Cycle 2 ATP Electron Transport Chain 32 ATP Total = 36 ATP

Efficiency of Cellular Respiration Depends on conditions of the cell How ATP are transported Aerobic respiration is 20 times more efficient than anaerobic respiration

Summary Cellular respiration Glycolysis Glucose  pyruvic acid + ATP + NADH Aerobic respiration Pyruvic acid  CO2 + H2O + ATP

Comparing Photosynthesis & Respiration Cellular Respiration Function Energy Storage Energy Release Location Chloroplasts Mitochondria Reactants CO2 and H2O C6H12O6 and O2 Products Equation 6CO2 + 6H2O  C6H12O6 + 6O2 C6H12O6 + 6O2 6CO2 + 6H2O