Cellular Respiration

Autotrophs and Heterotrophs Autotrophs – producers  Use simple inorganic compounds to produce complex organic compounds  Use external source of NRG  Types: Photoautotrophs  Carry out photosynthesis  Light as NRG source Chemoautotrophs  Use oxidation of inorganic compounds (H 2 S, NH 4 + compounds and Fe 2+ compounds) as energy Heterotrophs - consumers

Aerobes and Anaerobes Aerobes  Organisms which utilize O 2 to oxidize substances in order to obtain energy  Types: Obligate aerobes (must use O 2 at all times) – most animals, fungi, some bacteria Facultative aerobes (use O 2, but also have anaerobic methods to produce NRG) – yeast; even some human cells (use of lactic acid instead) Anaerobes  Organisms that do not utilize O 2 for NRG  Types: Obligate anaerobes (O 2 is poisonous) Facultative anaerobes (can be exposed to O 2 )

Digestion: Breaking Down Macromolecules into Monomers

Glucose is converted to pyruvate in the cytosol. Pyruvate enters the mitochondria.

Phosphorylation Types of Phosphorylation of ATP:  Substrate-level: Transfer of phosphate group to ADP from a reactive intermediate Not coupled with oxidation  Oxidative Production of ATP coupled with NADH or FADH 2 Requires chemiosmosis of H + ions across the matrix membrane (for the most part)

Stage 1 of Cellular Respiration: Glycolysis (no O 2 needed!) In the cytosol First step: Glucose gets phosphorylated!  This way it can’t diffuse out of the cell Remember: Transport of glucose across the membraneTransport of glucose across the membrane  PLUS: destabilization of the ether bond! End product: 2 molecules of pyruvate Net Reaction: Glucose + 2 ADP + 2 Pi + 2 NAD + -  2 pyruvate + 2 ATP + 2 NADH + 2 H + C 6 H 12 O ADP + 2 Pi + 2 NAD + -  2 C 3 H 3 O ATP + 2 NADH + 2 H + Animation

NRG yielding rxns Also this! NADH will be used to make later on more ATP

In Summary: Energy Yielding Rxns 1. glyceralgehyde 3 phosphate + Pi + NAD+  1,3 diphosphoglycerate + NADH NADH will be used to make more ATP in mitochondria 2. 1,3 diphosphoglycerate + ADP  3 phosphoglycerate + ATP 3. Phosphoenolpyruvate + ADP  Pyruvate + ATP

Net products from Glycolysis (per glucose) 2 pyruvate 2 NADH 2 ATP Total energy = kJ

If there’s no O 2 Pyruvate    Lactic Acid

If there is O 2

Fates of Pyruvate Depend on organism and conditions Yeast  Anaerobic (no oxygen) Pyruvate decarboxylase Makes alcohol  Aerobic Makes acetyl CoA ---  energy or fat Others  Anaerobic Makes lactate Sore muscles  Aerobic Oxidative decarboxylation of pyruvate into Acetyl Co A Acetyl Co A ---  energy or fat

The Krebs Cycle (aka TCA cycle) Pyruvate enters mitochondria and is converted to acetyl CoA (by acetyl coenzyme A)  Note: Major amounts of acetyl CoA are also produced by the oxidation of fatty acids Acetyl CoA is completely degraded to CO 2 and H 2 O Metabolism is dominated by the Kreb’s cycle

Krebs Cycle Per Glucose 2 full turns: 2ATP 8NADH 4FADH 2 Animation