Chapter 5 pt 2 Cellular Respiration

Cellular respiration: is the breakdown of organic compounds (especially glucose) into ATP (energy) to be used by the body. -Two types, aerobic (oxygen present) and anaerobic (oxygen not present). There are two stages of Cell Respiration, Glycolysis and ATP production. Stage 1: Breakdown of Glucose (Glycolysis) -Glycolysis is an enzyme assisted anaerobic process that breaks down one-six carbon molecule of glucose into two-three carbon pyruvate ions (pyruvate is the ion of 3-carbon organic acid called pyruvic acid).

The stages of glycolysis -Glucose is changed into a different 6 carbon compound, Uses 2 ATP. -This 6 carbon compound is then split into two 3 carbon compounds. -These 3 carbon compounds are changed into two different 3 carbon compounds, 2 NADH’s are made -The two 3 carbon compounds are changed into two 3 carbon pyruvates, 4 ATP’s are made. The numbers for glycolysis: 2 ATP are used, 4 ATP are made 2 “NET” ATP are generated by glycolysis 2 NADH’s are made 2 Pyruvates are made

Stage 2: ATP production -When oxygen is present (aerobic) pyruvates enter the mitochondrion and is converted to a two-carbon compound. -This reaction produces 1 carbon dioxide, one NADH, and one two-carbon compound called acetyl group. -The acetyle group is joined with a coenzyme A (called CoA for short) forming a compound called acetyl-CoA. -This compound will now enter the Krebs Cycle -Krebs Cycle is a enzyme assisted cycle designed to get a lot of energy carriers and some ATP from the energy that was originally stored in the pyruvate.

The basic steps: 1.acetyl-CoA combines with a 4 carbon compound forming a six- carbon compound (Coenzyme A is released). 2.NAD+ enters, changes molecule releasing a C, two H+’s, giving us CO2, NADH, and a H+ leaving a 5 carbon compound in the cycle. 3.Another CO2 is released, leaving a 4-carbon compound 4.NAD+ and ADP come in changing it to a different 4-carbon compound leaving as NADH and ATP 5.A new electron carrier FAD+ enters and leaves as FADH2 6.Another NAD+ enters leaving as NADH and the left over 4-carbon compound is ready to start the cycle again.

What was the purpose of the Krebs Cycle? -To get a bunch of energy carriers!!! The numbers The totals: (remember there were two pyruvates created by each glucose, so there for divide by 2 for a single turn of the cycle) - 6 NADH's are generated (3 per 1 acetyle-coa) - 2 FADH 2 is generated (1 per 1 acetyle-coa) - 2 ATP are generated (1 per 1 acetyle-coa) - 4 CO 2 's are released (2 per 1 acetyle-coa)

The ETC -Now that we have filled all the energy carriers, time to make ATP -Same basic idea as before, energy (from carriers NADH and FADH2) push H+ ions against their concentration gradient. -Water and O2 are byproducts of this ETC though. -H+ diffuse back into the “inner-mitochondrial matrix” via an ATP synthase making ATP -A total of 38 ATP’s can be generated from a single glucose molecule -2 came from glycolysis -2 came from Krebs cycle -34 came from conc. Grad. Created by ETC in the mitochondria

When oxygen isn’t present -fermentation: is the recycling of NAD+ using an organic hydrogen acceptor. -Two types: Lactic Acid and Alcoholic Lactic acid -Pyruvate is converted into Lactate (which is the ion of lactic acid) -We do this, think over exerting muscles, sore the next day -Lactic acid builds up in muscles, causes sourness

Alcoholic fermentation -Pyruvate is broken down to ethanol (ethyl alcohol), a two carbon compound. -CO2 is released in this process -Two step process -1-pyruvate is converted releasing co2 -2- e- are transferred from NADH to the carbon compound producing ethanol -*** NAD+ is recycled. -Been used in preparation of many foods and beverages -Wine and beer -Rising bread dough