Cellular Respiration Chapter 9 1 Cellular Respiration The

Cellular Respiration Chapter 9 -1

Cellular Respiration • The process in which cells make ATP by breaking down organic compounds, like glucose in the presence of oxygen. SUNLIGHT PHOTOSYNTHESIS C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O AEROBIC RESPIRATION

Glycolysis • A biochemical pathway in which glucose is oxidized (loses electrons) to produce pyruvic acid (pyruvate). start (glycolysis) in cytoplasm completed in mitochondrion

Glycolysis - Step #1 • Glucose is split into two, 3 carbon molecules of PGAL. And during this process 2 ATP molecules are used up.

Glycolysis Step #2 • The energy from the 2 PGAL molecules is used to make 4 ADP molecules and 2 molecules of NADH, an energy storing molecule.

Glycolysis Step #3 • 4 molecules of ATP are synthesized from 4 molecules of ADP.

Glycolysis #4 • In this step the phosphates added to make PGAL in step 1 are removed to make 2 molecules of puruvic acid. Even though it appears that 4 ATP molecules were made, there is only a net gain of 2 since 2 are used in step 1.

Products of Glycolysis • Small amounts of ATP • 2 molecules of Pyruvic Acid ATP

Conclusion and Glycolysis Chart • Location – Cytsol just outside the mitochondria • Function – Breaking down glucose to Pyruvic Acid • Reactants – Glucose ADP and NAD (accepts high energy electrons) • Products – ATP, NADH, Pyruvic • Acid.

Fermentation - Cytosol ( without oxygen) Anaerobic Respiration • Process: pyruvic acid (initial reactant )produced from glycolysis is converted to other organic compounds. • Fermentation does not produce ATP but does regenerate NAD+ which keeps glycolysis going.

Pathways of Fermentation • Two main pathways: lactic acid fermentation and alcoholic fermentation

Lactic Acid Fermentation • 1. An enzyme converts pyruvic acid into a 3 -C molecule called lactic acid (stored in your muscles – Soreness) • 2. During fermentation, NADH and H+ lose their hydrogen to pyruvic acid, resulting in NAD+.

Products • Occurs in making yogurt, cheese, and in your muscles.

GLYCOLYSIS C 6 H 12 O 6 2 ATP energy input 2 NAD+ 2 ADP 2 4 NADH ATP energy output 2 pyruvate 2 ATP net LACTATE FORMATION electrons, hydrogen from NADH 2 lactate Fig. 7. 9, p. 118

Alcoholic Fermentation • An enzyme converts pyruvic acid into ethyl alcohol in two steps: – Step -1. A CO 2 molecule is removed from the pyruvic acid, leaving a 2 -C molecule

• Step 2: Two hydrogen atoms from NADH are added to the 2 - carbon compound to form ethyl alcohol, also recycling NAD to return to • Glycolysis.

Products • Process results in the making of beer, wine, and bread.

GLYCOLYSIS C 6 H 12 O 6 2 ATP energy input 2 NAD+ 2 ADP 2 4 NADH ATP 2 pyruvate energy output 2 ATP net ETHANOL FORMATION 2 H 2 O 2 CO 2 2 acetaldehyde electrons, hydrogen from NADH 2 ethanol Fig. 7. 10, p. 119

Conclusion and Alcoholic Fermentation and Lactic acid Chart • • Location – Cytosol Function – Recycle NAD for glycolysis Reactants – Pyruvic Acid and NADH Alcohol Products - – Alcohol, Carbon Dioxide, NAD • Lactic acid Products – Lactic acid and NAD