Cellular respiration is the process by which cells convert sugars into energy. It occurs through aerobic respiration, which uses oxygen to break down fuels, or anaerobic respiration, which breaks down fuels without oxygen. Aerobic respiration yields much more ATP through glycolysis, the citric acid cycle, and oxidative phosphorylation using the electron transport chain. Anaerobic respiration yields less ATP through glycolysis followed by lactic acid fermentation or alcoholic fermentation.

2. Cellular Respiration
Cellular respiration is the process through which cells convert sugars into energy.
This is used by all cells to turn fuel
into energy that can be used to power
cellular processes.
Cellular respiration can be divided
into two categories depending upon
presence of absence of oxygen:
 Aerobic Respiration
 Anaerobic Respiration
https://www.biologyonline.com/tutorials/cell-respiration

3. Aerobic Respiration
 Aerobic respiration is the process by which organisms use oxygen to turn fuel, such
as fats and sugars, into chemical energy.
 It is the aerobic catabolism of nutrients to carbon dioxide, water, and energy.
 This type of ATP production is seen in aerobes and facultative anaerobes.
Aerobic respiration involves four stages:
 glycolysis,
 a transition reaction that forms acetyl coenzyme A,
 the citric acid (Krebs) cycle, and an electron transport chain and
 chemiosmosis.

4. Glycolysis
 glucose catabolism in which glucose is converted into pyruvate
 takes place in both aerobic and anaerobic organisms
Major Events:
 Glucose is oxidized into pyruvate.
 NAD+ is reduced to NADH.
 ADP is phosphorylated into ATP.

5. https://www.expii.com/t/glycolysis-cellular-respiration-summary-steps-10136

6. two moles of
pyruvate
four moles of ATPs (net
gain of 2 ATPs)
one mole of
NADH

7. Three possible catabolic fates of the pyruvate
https://quizlet.com/224455724/lccw-biochem-i-and-ii-fate-of-pyruvate-flash-cards/

8. Transition reaction that forms acetyl coenzyme A (Oxidative
decarboxylation)
 Pyruvate enters the mitochondrial matrix via a protein known as pyruvate translocase
 Pyruvate is combined with Coenzyme A to release a carbon dioxide molecule and
form acetyl-CoA
http://www.biosciencenotes.com/oxidative-decarboxylation-of-pyruvate/

9. Citric Acid Cycle
 Also called the tricarboxylic acid cycle or the Krebs cycle
 In eukaryotic cells, these reactions take place in the matrix of the mitochondria.
 In prokaryotic cells, it takes place in the cytoplasm.
Overall Reaction:

10. http://respirationresource.weebly.com/krebs-cycle.html

11. Net Output of
Krebs Cycle
Three hydrogen ions
One molecule of
FADH₂
Two molecules of
carbon dioxide
Three molecules of NADH One molecule of GTP

12. Electron Transport Chain
 Final stage of aerobic respiration
 located on the inner mitochondrial membrane
 Hydrogen carriers donate high energy electrons
 The electron carriers use this energy to pump hydrogen ions
 The accumulation of H+ ions creates an electrochemical gradient
H+ ions return to the matrix via the transmembrane enzyme ATP synthase (this diffusion
of ions is called chemiosmosis)
 a phosphorylation reaction which produces ATP
http://biologyaqaalevelnotes.blogspot.com/2017/09/energy-transfer-in-and-between.html

13. Net Yield of Aerobic Respiration
https://www.quora.com/How-is-36-ATP-produced-in-cellular-respiration

14. Anaerobic Respiration
 Cells can break down sugars to generate energy in the absence of oxygen.
 Instead of oxygen, anaerobic cells use substances such as sulfate, nitrate,
sulfur, and fumarate to drive their respiration
Steps:
1. Glycolysis
2. Incomplete oxidation
Types:
1. Lactic acid Fermentation
2. Alcoholic Fermentation
https://byjus.com/biology/cellular-respiration-aerobic-anaerobic/

15. Lactic acid Fermentation
 Glucose is split into two molecules of lactic acid to produce two ATP
 It occurs in certain types of bacteria and some animal tissues, such as
muscle cells
C6H12O6 (glucose)+ 2 ADP + 2 pi → 2 lactic acid + 2 ATP
https://www.microbialfacts.com/lactic-acid-fermentation-equation-reactants/

16. Alcoholic Fermentation
 Incomplete oxidation of glucose yields ethanol or ethyl alcohol.
 This process also produces two ATP per sugar molecule.
 occurs in yeast and even in some types of fish, such as goldfish
C6H12O6 (glucose) + 2 ADP + 2 pi → 2 C2H5OH (ethanol) + 2 CO2 + 2 ATP
https://www.ck12.org/biology/alcoholic-fermentation/lesson/alcoholic-fermentation-advanced-bio-adv/

17. Some Examples of Fermented Products
https://sfamjournals.onlinelibrary.wiley.com/cms/asset/026beca7-e429-4433-a5e0-b4dbdca74449/mbt212488-fig-0003-m.jpg