Anaerobic Cellular Respiration

Aerobic… What?

• We have reviewed aerobic respiration

• This is the process of taking molecules of glucose and breaking them down using oxygen from the environment

• It provides a huge amount of energy to a cell that can do it

Aerobic… What?

• This process makes roughly 32 ATP (remember that number is not set in stone)

• It also creates H2O and CO2

• Remember it can only be done by some organisms

Intro to Anaerobic Respiration

• When no oxygen is present or when a cell does not have mitochondria a different pathway is used after glycolysis

• After pyruvate is formed, the cells undergo fermentation

• Fermentation is the process of harvesting chemical energy without using oxygen

Intro to Anaerobic Respiration

• Fermentation does not actually increase the amount of ATP that the cell receives

• We have the 2 net ATP from glycolysis… and that’s it

• Fermentation only produces NAD+ so glycolysis can continue

• This means that fermentation produces no ATP, it just helps keep glycolysis running

Intro to Anaerobic Respiration

• Different types of organisms perform anaerobic respiration

• Obligate anaerobic organisms must have anaerobic conditions– Aerobic conditions will kill

them

• Facultative anaerobic organisms can have aerobic or anaerobic conditions

Lactic Acid Fermentation

• There are two main types of fermentation

• Lactic acid fermentation is the process of turning the pyruvate into lactate (an ionized form of lactic acid)

• Lactic acid fermentation happens in animal muscle cells and some bacteria

Lactic Acid Fermentation

• There are two main types of fermentation

• Lactic acid fermentation is the process of turning the pyruvate into lactate (an ionized form of lactic acid)

• Lactic acid fermentation happens in animal muscle cells and some bacteria

Lactic Acid Fermentation

• In lactic acid fermentation involves oxidizing NADH into NAD+ and converting what is left of the pyruvate into lactate

• The NAD+ is sent back to glycolysis to reload glycolysis with NAD+ that it needs to continue

Alcoholic Fermentation• Alcoholic fermentation

happens in fungi, some bacteria plant cells

• Yeast is the most common organism that does this

• It changes pyruvic acid to ethyl alcohol

• It also causes the loss of one molecule of CO2 and the gain of one NAD+

Alcoholic Fermentation

• Lactic acid fermentation takes pyruvate and converts it to a 2 carbon molecule known as ethanol

• This process oxidizes NADH into NAD+ and releases CO2 into the environment

Alcoholic Fermentation

• Alcoholic fermentation has been used by humans for hundreds of years

• This process gives us bread, cheeses, yogurts and alcohols

Video

• https://www.youtube.com/watch?v=FttkHVBu2IA

Other Macromolecules?

• Ok, we have broken down glucose…

• However other things can be broken down for energy

• Complex carbohydrates can be broken down into monosaccharides and given the same process

Other Macromolecules?

• Fats contain a high number of hydrogens

• This means they can easily be broken down in order to power oxidative phosphorylation

• Remember how fats contain 9kc/gram of energy

Other Macromolecules?

• Proteins can be used for fuel as well

• You body often will go through carbohydrates and fats first because they are easier to break down

• In order to be used, proteins must first be broken down to individual amino acids

Side By Side ComparisonType of Molecule Produced Lactic Acid

FermentationAlcoholic

FermentationAerobic Respiration

ATP 2 32

CO2 0 2 6

H2O 0 6