CELLULAR RESPIRATION WITHOUT OXYGEN

To the electron transport chain Respiration without oxygen is called: Anaerobic Respiration. The first part of Anaerobic respiration is the same as Aerobic : Glycolysis To the electron transport chain Pyruvic Acid

To the electron transport chain Glycolysis used 2 ATP To the electron transport chain Pyruvic Acid Broke into two 3-Carbon molecules called Pyruvic acid

Glycolysis produced: 2 net ATP’s (4-2 = 2) 2 NADH Now if Oxygen is not present, there are two pathways the pyruvic acid can take: Alcoholic Fermentation (does not occur in humans!) Lactic Acid Fermentation

1. Alcoholic fermentation After Glycolysis, you are left with 2 pyruvic acids, 2 NADH and 2 ATP. Glycolysis C Pyruvic Acid An enzyme “pyruvate decarboxylase” also attaches to the pyruvic acid causing it to release a CO2 molecule and leaving a 2 carbon molecule. pd C C C Acetaldehyde O

NADH gives back 2 high energy electrons to the pyruvic acid and turns back into NAD+ Then another enzyme (alcohol dehydrogenase) turns the 2-Carbon molecule into Ethyl alcohol. C ah Ethyl alcohol

Alcoholic fermentation by yeast is the most familiar form you might know. Yeast eat the glucose and convert it into ethanol which is a form of alcohol, and carbon dioxide… Beer… is made with yeast who eat the glucose, make the liquid alcoholic, and the CO2 is the little bubbles you see in beer.

Yeast is also used in baking not to make alcoholic bread, but for Carbon dioxide. The released gas puts small gas pockets through out the dough causing your bread to have that holed texture.

So in a chemical equation: Pyruvic acid + enzymes + NADH → alcohol + CO2 + NAD+ Now let’s look at Lactic acid fermentation which does occur in your body. Again we begin just after Glycolysis with the forming of pyruvic acid. So we start with 2 ATP C Glycolysis

NADH plus an enzyme (lactate dehydrogenase) both act on the 3-Carbon pyruvic acid. ld C NAD NADH This causes the 3-Carbon molecule to chemically change into a 3-carbon molecule called “Lactic Acid” C C C

So chemically: Pyruvic acid + enzyme + NADH → Lactic Acid + NAD When running hard, you normally do not breathe enough oxygen to keep up with the demand that your muscles are asking for. Since there is limited oxygen, your muscles start to produce ATP through lactic acid fermentation. This acid starts to cause a burning sensation over your muscles.

When using your muscles during some form of exercise…you ever get a cramp? What has happened is that the pyruvate in the muscle has to feed the muscle without oxygen You are pushing yourself as hard as you can…. So because the muscles themselves are using up most of the oxygen, your body converts pyruvate into lactate to get you ATP to continue.. After a short period of time you muscles start to hurt. This is because the lactic acid has built up so much on your muscles…you cramp in pain.

So how do you get rid of the lactic acid on your muscles then? Oxygen! You need to breathe to break down the lactic acid, so many athletes inhale pure oxygen afterwards… You , just rest and breathe real hard…

So what method is best? Cellular respiration for energy OR lactic acid fermentation. For quick burst of energy “fight or flight” reflex you normally use lactic acid fermentation. For most others, you use cellular respiration, but it releases energy more slowly, so you tend to pace yourself over longer times so you won’t cramp up or become too exhausted.

Comparing Photosynthesis & Cellular Respiration Function Location Reactants Products Equation Energy Capture Energy Released Chloroplasts Mitochondria CO2 and H2O C6H12O6 (glucose) and O2 C6H12O6 (glucose) and O2 CO2 and H2O 6 CO2 + 6 H2O → C6H12O6 + 6 O2 C6H12O6 + 6 O2 → 6 CO2 + 6 H2O Energy Energy Creature Plants, algae, some bacteria Animals, some bacteria

VOCABULARY ! Anaerobic Respiration Alcoholic Fermentation Pyruvate decarboxylase Ethyl alcohol Lactic Acid Fermentation