CELLULAR RESPIRATION

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 through photosynthesis 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: 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 Repiration 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 6 CO2 + 6 H2O + 36 ATP oxidized reduced ENERGY

http://www.youtube.com/watch?v=8t270WJvM_g

Adenosine triphosphate

ATP Nitrogen base (Adenine) 3 phosphate groups Ribose sugar

ATP releases energy ATP ADP + Pi + Energy Phosphate bonds are high energy bonds Adenosine Diphosphate (ADP) + Pi 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 Susbtrate-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 that 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.

Uses NAD+ and FAD+ which are co-enzymes that will move electons and energy from one molecule to another A dehydrogenase enzyme catalyzes the reaction It removes 2 H atoms (so 2 protons, and 2 electrons) from glucose Delivers 2H+ & 2 e– to NAD+ to make NADH (the other H+ is dissolved in the surrounding solution)

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

4 STAGES GLYCOLYSIS – in cytoplasm (no O2 required) 2) PYRUVATE OXIDATION – in mitochondrial matrix 3) KREB 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

Glucose (C6) P- C6-P 2 C3-P 2 P-C3-P 2 pyruvate (C3) Summary of Glycolysis Glucose is converted into 2 pyruvate molecules Free energy is captured in ATP and NADH Glucose (C6) P- C6-P 2 C3-P 2 P-C3-P 2 pyruvate (C3) 2 ATP 2 ADP 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.