Cellular Respiration

The Equations… Photosynthesis: 6CO2 + 6H2O + energy  C6H12O6 + 6O2 (sun) Cell Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP)

Cellular Respiration…What is it? -process by which cells produce ATP by breaking down organic compounds. Why is it important? -cells need “usable” forms of energy to function and maintain homeostasis. ATP is the usable form.

Overview of Cell Respiration…

Pathway 1: Glycolysis Function: -anaerobic (no oxygen) -organic compounds (sugar) is converted to pyruvic acid. -ATP and NADH molecules are produced. (reduction reaction) Location: cytosol Reactants: organic compounds (sugar) Products: 2 pyruvic acid 2 NADH (energy) 2 ATP’s (energy)

Pathway 2 (if no oxygen is present): Fermentation Function: -no oxygen is present -NADH NAD+ (recycled back to glycolysis) Many types of fermentation pathways, but two of the more common are: 1. Lactic Acid Fermentation 2. Alcoholic Fermentation Location: cytosol

Lactic Acid Fermentation Reactants: pyruvic acid NADH Product: NAD+ lactic acid -Lactic Acid Fermentation is important in the manufacturing of various foods. (yogurt, cheese) -Athletes also experience Lactic Acid buildup…cramping and fatigue.

Alcoholic Fermentation Reactants: pyruvic acid NADH Product: NAD+ alcohol -Process occurs in plants and yeast. -This process is important in making bread and alcohol products.

Pathway 2 (if oxygen is present): Aerobic Respiration Function: two stages: 1. Krebs cycle 2. ETC & Chemiosmosis -produce majority of the ATP -pyruvic acid is converted to Acetyl Coa Location: eukaryotes- mitochondrial matrix (Krebs) & the inner mitochondrial membrane (ETC) prokaryotes- cytoplasm & cell membrane

Krebs Cycle (Citric Acid Cycle) Reactants: Acetyl CoA Products: CO2 (given off as a waste product) ATP (2 molecules) NADH, FADH2

Electron Transport Chain & Chemiosmosis (uses enzyme: ATP synthase) Reactants: NADH, FADH2 Products: ATP (34 molecules) water (given off as a waste product)

Final Analysis: Net production of ATP through aerobic respiration…38 ATP (2 from glycolysis 2 from Kreb’s and 34 from ETC/Chemiosmosis) Aerobic Respiration is much more efficient in producing ATP! Why…oxygen is present.