Lec 6

Fermentation and Cellular Respiration ◦Fermentation  the degradation of a sugar that occurs without the help of oxygen What type of Metabolic pathway is fermentation is it Catabolic or is it Anabolic? ◦Catabolic

Fermentation Two types of Fermentation ◦Alcohol fermentation ◦Lactic acid fermentation

Alcohol Fermentation Pyruvate converted to ethanol ◦2 Steps  1 st step releases CO 2 from pyruvate  2nd step acetaldehyde reduced by NADH to ethanol

LE 9-17a CO H + 2 NADH2 NAD + 2 Acetaldehyde 2 ATP 2 ADP + 2 P i 2 Pyruvate 2 2 Ethanol Alcohol fermentation Glucose Glycolysis

Lactic acid Fermentation Pyruvate is reduced directly by NADH, ◦Forms lactate as an end product ◦no release of CO 2 Lactic acid fermentation ◦fungi and bacteria to make cheese and yogurt Human muscle cells use lactic acid fermentation ◦ to generate ATP when O 2 is scarce

LE 9-17b + 2 H + 2 NADH2 NAD + 2 ATP 2 ADP + 2 P i 2 Pyruvate 2 Lactate Lactic acid fermentation Glucose Glycolysis

Fermentation The ATP made during fermentation is generated by what? ◦Substrate-level phosphorylation What is substrate-level phosphorylation? - Production of ATP from ADP by direct transfer of a high-energy phosphate group from a phosphorylated intermediate

Fermentation What type of Metabolic pathway is substrate- level phosphorylation? (Catabolic or Anabolic) ◦Catabolic pathway (Release energy) What type of reaction is substrate-level phosphorylation? (exergonic or endergonic?) ◦Exergoinic (energy outward) So ∆G would be? ◦negative

Cellular Respiration ◦Oxygen is consumed as a reactant along with the organic fuel What type of Metabolic pathway is Cellular Respiration? In Eukaryotic cells what is the main area/compartment of cellular respiration? What is the “Fuel” for cellular respiration?

Redox Reactions Oxidation-reduction reactions ◦A transfer of one or more electrons from one reactant to another Oxidation ◦the loss of electrons from one substance Reduction ◦the addition of electrons to another substance

Redox Reactions Where does the Oxidation and Reduction Occur?

Redox Reactions Na – is oxidized the loss of electrons Cl – is reduced the gain of electrons What is the Reducing Agent and what does it reduce? What is the Oxidizing agent and what does it oxidize?

Redox Reactions What is the Reducing Agent and what does it reduce? Na – is the Reducing agent (electron donor) Cl – is Reduced What is the Oxidizing agent and what does it oxidize? Cl – is the Oxidizing agent (electron acceptor) Na – is Oxidized

Redox Reactions Where does the Oxidation and Reduction Occur?

Redox Reactions

Cellular Respiration During cellular respiration, the fuel (such as glucose) is oxidized and oxygen is reduced: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy becomes oxidized becomes reduced Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds This is what occurs here the IMPORTANT point is that the change in the covalent status of electrons as hydrogen is transferred to oxygen is what liberates energy

Cellular Respiration Is a series of steps ◦Cellular respiration DOES NOT oxidize glucose in a single step that would transfer all the hydrogen from the fuel to the oxygen at one time. ◦Fuel, glucose is broken down in steps ◦Each step is catalyzed by an enzyme. Hydrogens are stripped from glucose then usually passed first to the coenzyme NAD + ◦NAD + functions as an Oxidizing agent ◦NAD + + H  NADH

Videos Krebs Cycle ◦ Glycolysis ◦ 4Oyohttp:// 4Oyo ◦ Making ATP (make it rain remix) Kreb Cycle ◦ eature=relatedhttp:// eature=related