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Course: High school biology > Unit 3
Lesson 6: Cellular respirationCellular respiration review
Key Terms
| Term | Meaning |
|---|---|
| Cellular respiration | The process by which organisms break down glucose into a form that the cell can use as energy |
| ATP | Adenosine triphosphate, the primary energy carrier in living things |
| Mitochondria | The eukaryotic cell structure where cellular respiration occurs |
| Cytoplasm | The contents of a cell between the plasma membrane and the nuclear envelope; includes cytosol which is the jelly-like substance that fills the space between organelles |
| Aerobic | Process that requires oxygen |
| Anaerobic | Process that does not require oxygen |
| Fermentation | An anaerobic pathway for breaking down glucose |
Cellular respiration
Cellular respiration can occur both aerobically (using oxygen), or anaerobically (without oxygen).
During aerobic cellular respiration, glucose reacts with oxygen, forming ATP that can be used by the cell. Carbon dioxide and water are created as byproducts.
The overall equation for aerobic cellular respiration is:
The three stages of aerobic cellular respiration are glycolysis (an anaerobic process), the Krebs cycle, and oxidative phosphorylation.
Fermentation
Some organisms are able to continually convert energy without the presence of oxygen. They undergo glycolysis, followed by the anaerobic process of fermentation to make ATP.
- Muscle cells can continue to produce ATP when oxygen runs low using lactic acid fermentation. However, this often results in muscle fatigue and pain.
- Many yeast use alcoholic fermentation to produce ethanol. For this reason, humans have domesticated yeast to use for many commercial purposes including baking as well as beer and wine production.
Aerobic vs anaerobic respiration
| Aerobic | Anaerobic | |
|---|---|---|
| Reactants | Glucose and oxygen | Glucose |
| Products | ATP, water, CO | ATP and lactic acid (animals); or ATP, ethanol, and CO |
| Location | Cytoplasm (glycolysis) and mitochondria | Cytoplasm |
| Stages | Glycolysis (anaerobic), Krebs cycle, oxidative phosphorylation | Glycolysis, fermentation |
| ATP produced | Large amount (36 ATP) | Small amount (2 ATP) |
Common mistakes and misconceptions
- Anaerobic respiration is a normal part of cellular respiration. Glycolysis, which is the first step in all types of cellular respiration is anaerobic and does not require oxygen. If oxygen is present, the pathway will continue on to the Krebs cycle and oxidative phosphorylation. However, if oxygen is not present, some organisms can undergo fermentation to continually produce ATP.
- Plants undergo cellular respiration. Many people believe that plants undergo photosynthesis and animals undergo respiration. Really, plants do both! Plants simply undergo photosynthesis first as a way to make glucose. Animals don't need to photosynthesize since they get their glucose from the food they eat.
- Cellular respiration is not simply the same as "breathing." This can be confusing! People often use the word "respiration" to refer to the process of inhaling and exhaling. However, this is physiological respiration, not cellular respiration. The two are related processes, but they are not the same.
Want to join the conversation?
Here u say that at the end of the Aerobic ( Cellular) respiration 38/36 ATP will be released. At the same time, in some books say 32/30 ATP will release in the Cellular respiration. Moreover, they gave the steps as well.
Total number of ATP molecules produced from one molecule of glucose, during aerobic respiration.
In glycolysis :
As ATP 2ATP
From 2NADH 5ATP (oxidation phosphorylation)
In pyruvate oxidation;
From 2NADH 5ATP (oxidative phosphorylation)
In Citric acid cycle;
As ATP ATP (substrate level phosphorylation)
From 6NADH 15ATP (oxidative phosphyrlation)
From 2 FADH2 3ATP
Total Number ATP = 32 ATP
I think here is a wrong. Pls help me to solve this doubt.(17 votes)
Depending on your teacher or textbook, the amount of ATP produced during aerobic respiration is either 30-32 or 36-38. Both are technically correct, but recent studies show that 30-32 is more accurate. While 36-38 ATP being produced is possible it only happens in the most ideal situations.(20 votes)
I've read in a test prep text book that water is an input in the process of cellular respiration but I have not seen the same in this article or the accompanying video; is it true or false?(11 votes)- Water is indeed used in cellular respiration. During Krebs cycle one molecule reacts with fumarate forming malate.
But it is also produced during ETC so basically (the net) water is product.(11 votes)
Where does the water go after being produced as a byproduct? Is it sweat or urine or does it stay in the body? Thanks.(9 votes)
it can become part of sweat or urine and leave the body, but it can also just join the multitude of water already in your body and go wherever the other water goes. it can even become water vapor and exit through your breath, just like the carbon dioxide.(14 votes)
- why is cellular respiration not the same as "breathing"(7 votes)
Breathing has to do with taking in oxygen. Cellular respiration is where glucose is broken down into its chemical potential energy and stored as ATP (Adenosine triphosphate.(12 votes)
- I get that they also perform photosynthesis but how do carnivorous plants break down the animals they feed on into glucose?(7 votes)
Venus flytraps use enzymes to break down their catch, and use it for nitrogen, since they are deprived, and produce glucose the same way, just not as much(6 votes)
- Hi! May I know is fermentation part of cellular respiration? Or it is not cellular respiration because it is another pathway of obtaining ATP?(4 votes)
Fermentation is the anaerobic process of producing ATP, so yes, it counts as cellular respiration. However, it is anaerobic, meaning it does not use oxygen to produce ATP.
In humans and other creatures, this process is usually much less effective than using oxygen and may have unwanted side effects. (For humans, it produces lactic acid, which causes muscle pain and fatigue.)
Hope this helps.(4 votes)
- What happens when Cellular respiration is increased in cells?(5 votes)
- The cells get more energy, but at the cost of using more resources.(1 vote)
- where they get the name krebs in krebs cycle(3 votes)
- In 1953, Hans Adolf Krebs was awarded the Nobel Prize of Physiology or Medicine for discovering the citric acid cycle which we all call the Krebs Cycle. However, it was in 1937 that he first discovered it and its importance.(5 votes)
does both anaerobic and aerobic respiration occur simultaneously during exercise(4 votes)
when we are exercising, initially there will be aerobic respiration.
but as the amount of oxygen requirement increases, the respiration will become anaerobic and thereby producing lactic acid in our muscle cells and causing muscle cells.
hope it would be helpful to you :)(1 vote)
- hoe long respiration takes to occur(3 votes)
- Extremely fast. Likely within milliseconds or even less than a millisecond. Its hard to say because its difficult to observe the process happening in a living cell.(2 votes)