Cellular Respiration

Overview

Organic Compounds Glycolysis Oxygen present Aerobic Respiration ATP Oxygen Absent Fermentation

Glycolysis 1 6-C molecule is oxidized to produce 2 3-C molecules of Pyruvic Acid All reactions take place in the cytosol of the cell Has a net yield of 2 ATP molecules for every glucose converted to pyruvic acid

Fermentation DOES NOT PRODUCE ATP NO OXYGEN Regenerates NAD+ 2 common Pathways Lactic Acid Ethyl Alcohol NAD+ used to keep glycolysis going to produce ATP

LACTIC ACID Pyruvic Acid converted into another 3-C compound (lactic Acid) Involves the transfer of 2H atoms from NADH and H+ to pyruvic acid Plays a major role in manufacturing food products Occurs in muscles during strenuous exercise Eventually LA will be transported back to liver where converted back to pyruvic acid NADH is oxidized to NAD+---then used in glcolysis ---reduced to NADH Food products such as yogurt and cheese

ALCOHOLIC FERMENTATION Yeast cells are added 2 step pathway CO2 molecule is removed from pyruic acid Leaves a 2-C compound 2H atoms are added to the 2-C compound to make ethyl alcohol H atoms come from NADH &H+ regenerating NAD+ Basis for wine beer and bread production Bread can release O2

Energy yield Complete oxidation of glucose releases 686 kcal How efficient are the anaerobic pathways at obtaining energy from glucose and using it to make ATP from ADP? Complete oxidation of glucose releases 686 kcal Production of a standard amount of ATP from ADP absorbs 12 kcal 2 ATP are produced from every glucose molecule broken down by glycolysis Efficiency of Energy required to make Glycolysis ATP == ------------------------------------------ Energy released by oxidation of glucose

Efficiency of glycolysis = 3.5% Much of the original energy contained in glucose is still held in pyruvic acid NOT VERY EFFICIENT Larger animals have greater energy requirements that cannot be satisfied by anaerobic pathways