Fermentation Chapter 6

What you need to know! The difference between fermentation and cellular respiration.

Aerobic vs. Anaerobic Aerobic = with air –Aero is Greek for air –Air = oxygen Anaerobic = without air –An as a prefix means no; An (no) aero (air) Aerobic respiration = cellular respiration Anaerobic respiration = fermentation

Fermentation Glycolysis is the metabolic pathway that yields ATP during fermentation –Yields: Write the products of glycolysis here Eventually a cell will run out of NAD+ –No more glycolysis Fermentation recycles the NADH back into NAD+

Types of Fermentation 1.Lactic acid fermentation: –NADH  NAD+ –Pyruvate  lactate (lactic acid) –Causes muscle soreness –Filtered by the liver 2.Alcohol fermentation –NADH  NAD+ –Pyruvate  CO 2 & ethanol (ethyl alcohol) –CO 2 puts bubbles in beer and champagne and makes dough rise

Types of Fermentation

ATP Yield Anaerobic yields 4 ATP during glycolysis –2 ATP activation cost Net Gain 2 ATP Aerobic yields 40 ATP during all 3 steps –2 ATP activation cost Net Gain 38 ATP Aerobic respiration is 19 X’s more efficient per glucose molecule

Various Metabolisms Obligate (strict) aerobes –Organisms that require oxygen to survive –Ex: all vertebrates Facultative anaerobic organisms –Can do aerobic or anaerobic cellular respiration (CR) depending on the situation –Ex: yeast, muscle cells Obligate (strict) anaerobes –Require oxygen free environment (die in the presence of O 2 ) –Ex: deep soil and stagnant pond bacteria

Food Not everything you eat is broken down into glucose Fat yields double the ATP of carbs Food also provides essential bio-chemicals for growth

Summary

Sample Questions When an organism such as a yeast lives by fermentation, it converts the pyruvic acid from glycolysis into a different compound, such as alcohol. Why doesn’t it secrete the pyruvic acid directly? a)The conversion yields one ATP per pyruvic acid molecule. b)The conversion yields one NADH per pyruvic acid molecule. c)The conversion yields one FADH2 per pyruvic acid molecule. d)The conversion is needed to regenerate the NAD+ consumed during glycolysis. e)A buildup of pyruvic acid in the surrounding environment would be too toxic. If you consume one gram of each of the following, which will yield the most ATP? a)Fatb) Glucosec) Sucrosed) Proteine) Starch