CELLULAR RESPIRATION (An Introduction) 3.7 & & 8.1

Organisms use energy from ATP for all its activities Breathing Heart pumping Maintaining body temperature Thinking, dreaming www.sxc.hu/photo/ 437515

AUTOTROPHS - all organisms require energy and have evolved to take free energy from the environment and convert it into usable forms AUTOTROPHS: create their own food (which will later be broken down into usable energy)

AUTOTROPHS 1) Photoautotrophs: Organisms that use photosynthesis to convert light energy into chemical potential energy in glucose ex: green plants

Autotrophs.... 2) Chemoautotrophs: Sulfolobus acidocaldarius 2) Chemoautotrophs: microorganisms the are able to extract energy from inorganic compounds containing elements such as sulphur and iron usually found in extreme environments such as volcanoes, sulfur springs Ex: archaebacteria

HETEROTROPHS… HETEROTROPHS: must consume autotrophs or other heterotrophs in order to gain energy. Includes the majority of organisms (including all animals and fungi, many protists and bacteria) - all organisms except chemoautotrophs use glucose (C6H12O6) as their primary source of energy.

Cellular Respiration The process of extracting energy from nutrient molecules (ie glucose) and storing it into a usable form (ATP) so the cell can use it for energy-requiring activities. Overall equation: C6H12O6 + 6O2 + 36ADP + 36Pi 6 CO2 + 6 H2O + 36 ATP oxidized reduced ENERGY

Cellular Respiration It is a combustion reaction! (Glucose is reacted with Oxygen to produce energy) In cellular respiration, several enzymes are used to lower the overall activation energy of the reaction and to maximize the amount of energy that can be produced

Gummy Bear An oxidation (combustion) reaction. If our bodies relied upon heat and not enzymes to harvest energy from glucose! https://www.youtube.com/watch?v=MUensqImzXM

Redox Reactions Reduction – oxidation reactions. Reduction – when a compound gains an electron Oxidation – when a compound loses an electron.

Helpful Memory Tricks: “LEO the lion goes GER” LEO: Loss of electrons is oxidation GER: Gain of electrons is reduction “OIL RIG” OIL: oxidation is loss (of electrons) RIG: reduction is gain (of electrons)

Example Na + Cl  NaCl Na Cl  [Na]+ [ Cl ]- OXIDIZED REDUCED (Oxidizing Agent – allows Na to be oxidized) (Reducing Agent – allows Cl to be reduced)

Redox Reactions During redox reactions, electrons are passed from molecule to molecule in sequence (moves to more electronegative compounds) As it is passed along, the molecules will be reduced and oxidized. This movement of electrons is a form of energy (electrochemical energy) and can be converted into other forms….

Redox Reactions B C- D A- C B- D- A Increasing electronegativity

Adenosine triphosphate

ATP Nitrogen base (Adenine) 3 phosphate groups Ribose sugar

Diphosphate +phosphate ATP releases energy Phosphate bonds are high energy bonds Diphosphate +phosphate Breaking the bonds releases the energy ATP ADP + Pi + Energy

ATP is Recycled ATP is an energy-containing molecule used to supply the cell with energy. The energy to produce ATP comes from glucose or other high energy compounds ATP is continuously produced and consumed Phosphorylation = attaching a phosphate group to a molecule to make the molecule more reactive

Overall 3 goals of cellular respiration: Breaks bonds between 6 carbon atoms (of C6H12O6 ) to make 6 CO2 Moves H atom electrons from C6H12O6 to O2 to make 6 H2O Trap as much free energy as possible in ATP

Energy Transfer Aerobic Respiration occurs via 2 different energy transfer mechanisms Substrate-Level Phosphorylation Oxidative Phosphorylation

A) SUBSTRATE LEVEL PHOSPHORYLATION ATP is produced directly in an enzyme catalyzed reaction. The enzyme transfers a phosphate group from a substrate molecule (ie PEP) to ADP to make ATP

Page 95 figure 2 Pg 94 Figure 2: the enzyme allows Pi group to transfer to ADP to make ATP

B) OXDATIVE PHOSPHORYLATION ATP is formed indirectly It is more complex than substrate-level phosphorylation and makes much more ATP ATP is formed via a series of redox reactions where O2 is the final electron acceptor The energy released during the redox reactions is used to generate ATP.

A dehydrogenase enzyme catalyzes the reactions; NAD+  NADH Uses NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) which are co-enzymes that will move electrons and energy from one molecule to another A dehydrogenase enzyme catalyzes the reactions; NAD+  NADH The enzyme removes 2 H atoms (so 2 protons, and 2 electrons) from glucose Delivers 1 H+ & 2 é to NAD+ to make NADH (the other H+ is dissolved in the surrounding solution) FAD  FADH2 FAD is also reduced by 2 hydrogen (2 H+ & 2 é) They both eventually transfer their free energy to ATP

oxidized form reduced form FAD + (2H + + 2é) FADH2 NAD+ + H + + 2é NADH oxidized form reduced form FAD + (2H + + 2é) FADH2 Stores energy- most of which will be transferred to ATP

4 STAGES 1)GLYCOLYSIS – in cytoplasm 2) PYRUVATE OXIDATION – in mitochondrial matrix 3) KREBS CYCLE – in mitochondrial matrix 4) ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS – inner mitochondrial membrane Aerobic respiration

Mitochondria OUTER MITOCHONDRIAL MEMBRANE - Similar function to cell membrane INNER MITOCHONDRIAL MEMBRANE Assists with cellular respiration embedded with many proteins and enzymes MATRIX - Inner, fluid filled section INTERMEMBRANE SPACE - Fluid filled space between the inner and outer membranes CRISTAE - Folds of the inner membrane

Stage 1: GLYCOLYSIS A 10 step process that occurs in the cytoplasm of the cell Does not require oxygen (anaerobic) During glycolysis, glucose is broken down into 2 molecules of pyruvate 2 ATP molecules are used to phosphorylate and activate compounds 4 ATP are produced (Net 2ATP) and 2 NADH produced

Summary of Glycolysis 2 ATP 2 ADP Glucose (C6) P- C6-P (fructose 1, 6 biphosphate) 2 C3-P (G3P-glyceraldehyde 3-phosphate) 2 P-C3-P (BPG 1,3-biphosphoglycerate) 2 pyruvate (C3) 2 ATP 2 ADP Glucose is converted into 2 pyruvate molecules Free energy is captured in ATP and NADH 2 NAD+ 2 NADH 2 Pi 2 ADP 2 ATP

2 net ATP produced (4 produced but 2 used in the process) – which can be used by the cell immediately 2 NADH produced – which can be processed to produced more ATP The 2 pyruvate molecules will now go to the mitochondrial matrix for aerobic respiration If oxygen is not available, fermentation will occur instead.