Fermentation
Summary
TLDRThe video script explores the importance of oxygen in cellular respiration and how organisms adapt to its absence. It explains the process of ATP production, the misconception about plants needing oxygen, and the shift to fermentation in anaerobic conditions. Examples include alcoholic fermentation by yeast and lactic acid fermentation in muscle cells, emphasizing the limited ATP yield compared to aerobic respiration.
Takeaways
- đ Swimming was the speaker's favorite childhood activity, and they had a childhood misconception about fish not needing oxygen.
- đ Most fish use gills to extract oxygen from water, debunking the speaker's early belief that fish don't need oxygen.
- đż Oxygen is essential for a variety of organisms, including humans, fish, and plants, which counteracts the common misconception about plants not needing oxygen.
- đŹ Cells require oxygen for cellular respiration, a process that uses oxygen to break down glucose and produce ATP, the energy currency of cells.
- đ ATP, or adenosine triphosphate, is a molecule with high energy potential, crucial for powering many cellular functions.
- â»ïž During cellular respiration, ATP can be converted to ADP and back again, with the help of enzymes, to sustain cellular energy needs.
- đ When oxygen is absent, certain cells and organisms, like some bacteria, archaea, yeast, and muscle cells, can resort to anaerobic respiration or fermentation to produce ATP.
- đș Fermentation is an anaerobic process that allows glycolysis to continue by regenerating NAD+, with different products like ethanol in alcoholic fermentation and lactate in lactic acid fermentation.
- đ Yeast performs alcoholic fermentation to make bread rise, utilizing the carbon dioxide produced and generating a small amount of alcohol that evaporates during baking.
- đïžââïž Lactic acid fermentation occurs in muscle cells under oxygen debt, such as during intense exercise, and may not be the direct cause of post-exercise muscle soreness as previously thought.
Q & A
What was the speaker's childhood fascination with swimming?
-The speaker loved swimming and was on the swim team starting at the age of four. They dreamed of being like a fish and even had a misconception that fish didn't need oxygen.
How do most fish obtain the oxygen they need?
-Most fish have gills that allow them to extract the oxygen they need from the water.
What is the role of oxygen in cellular respiration?
-Oxygen is a reactant in cellular respiration, needed to break down glucose to form ATP (adenosine triphosphate), which powers many cellular processes.
Why do plants, which produce oxygen through photosynthesis, still need oxygen?
-Although plants produce oxygen during photosynthesis, they also need oxygen for cellular respiration, as they perform respiration and thus require oxygen for their own cells.
What happens to ATP after it loses a phosphate?
-When ATP loses a phosphate, it becomes ADP (adenosine diphosphate), which has two phosphates.
What is the difference between aerobic and anaerobic cellular respiration?
-Aerobic cellular respiration requires oxygen, while anaerobic respiration does not. Anaerobic respiration occurs in the absence of oxygen, and organisms like some bacteria and archaea can perform it using alternative electron acceptors.
How do muscle cells handle a lack of oxygen during intense exercise?
-Muscle cells can shift to lactic acid fermentation when oxygen is scarce, such as during intense exercise, allowing them to continue producing ATP through glycolysis.
What is fermentation and why is it important for organisms in low oxygen conditions?
-Fermentation is a process that allows glycolysis to continue and produce ATP in the absence of oxygen. It is important for organisms as it provides a way to generate energy when oxygen is limited.
How does alcoholic fermentation differ from lactic acid fermentation?
-In alcoholic fermentation, pyruvate is converted into acetaldehyde, which then produces carbon dioxide and ethanol. In lactic acid fermentation, pyruvate is converted directly into lactate, which can contribute to muscle soreness.
What is the role of NAD+ and NADH in glycolysis and fermentation?
-NAD+ is an oxidizing agent that is reduced to NADH when it gains electrons during glycolysis. In fermentation, NADH gives its electrons to an electron acceptor to be oxidized back into NAD+, which is necessary for glycolysis to continue.
How does the process of fermentation relate to the production of bread and yogurt?
-Fermentation is used by yeast in bread making to produce carbon dioxide, which helps the bread rise, and by bacteria in yogurt production, where lactic acid contributes to its sour taste.
Outlines
đ The Wonder of Water and the Need for Oxygen
This paragraph introduces the speaker's childhood love for swimming and the dream of being like a fish. It clarifies a common misconception about fish not needing oxygen, explaining that most fish use gills to extract oxygen from water. The paragraph emphasizes the importance of oxygen for various organisms, including humans and plants, and delves into the cellular process of respiration. It explains how cells use oxygen to produce ATP, a crucial molecule for cellular energy, through a process called cellular respiration. The video also touches on the misconception that plants do not need oxygen, highlighting that they require it for cellular respiration despite producing oxygen through photosynthesis.
đ Fermentation: Life Without Oxygen
The second paragraph explores what happens when oxygen is scarce, focusing on fermentation as a process that allows cells to produce ATP without oxygen. It discusses two types of fermentation: alcoholic fermentation, which is used by yeasts to produce ethanol and carbon dioxide, and lactic acid fermentation, which occurs in muscle cells during intense exercise and is also used in the production of yogurt. The paragraph explains how fermentation regenerates NAD+, an essential coenzyme for glycolysis, by using pyruvate or its derivatives as electron acceptors. It also mentions the role of ATP in cellular processes and how fermentation, while effective, is less efficient than aerobic respiration in ATP production.
Mindmap
Keywords
đĄOxygen
đĄGills
đĄCellular Respiration
đĄATP (Adenosine Triphosphate)
đĄAerobic
đĄAnaerobic Respiration
đĄFermentation
đĄGlycolysis
đĄNADH and NAD+
đĄElectron Transport Chain
đĄLactic Acid Fermentation
Highlights
Swimming was a childhood passion, starting at a young age.
The misconception that fish don't need oxygen is clarified.
Most fish use gills to extract oxygen from water.
The importance of oxygen for various organisms is emphasized.
Plants require oxygen despite producing it through photosynthesis.
The necessity of oxygen for cellular respiration is explained.
ATP, or adenosine triphosphate, is the primary energy currency in cells.
The conversion between ATP and ADP is crucial for cellular energy.
Aerobic cellular respiration is a complex process requiring oxygen.
The video focuses on cellular processes in the absence of oxygen.
Some bacteria and archaea can perform anaerobic respiration.
Yeast and muscle cells can handle low oxygen environments.
Fermentation is a process that allows ATP production without oxygen.
Glycolysis is a key step in both aerobic and anaerobic processes.
Alcoholic fermentation by yeast produces ethanol and carbon dioxide.
Lactic acid fermentation is used by muscle cells during oxygen debt.
Lactic acid fermentation's role in yogurt production is mentioned.
Fermentation's limitation in ATP production compared to aerobic respiration.
Transcripts
Captions are on! Click CC at bottom right to turn off.
When I was a kid, swimming was one of my favorite things to do.
I was on the swim team starting when I was four years old and then on and off throughout
grade school, although I wasnât especially fast.
I just loved the water.
I used to dream that there was a way I could be like a fish.
When I was little, I had a misconception that fish didnât need oxygen.
Later on, I learned that, no, most fish have gills that allow them to extract the oxygen,
which they need, from the water.
So then I just thought itâd be really cool if I just had gills.
But, alas, no gills for Pinky.
Oxygen is a really big deal---so many organisms---from fish to plants to humans---need oxygen.
And yes, even though plants make oxygen in photosynthesisâŠthey still perform cellular
respiration and therefore plants still need oxygen themselves.
Thereâs often a misconception that plants donât need oxygen; thatâs just not true.
So why do these organisms need oxygen?
Itâs similar to why you need oxygen.
If youâve ever wondered why you need to breathe, which is done by the respiratory
system in your body, zoom into the cell level.
Cells in your body use the oxygen you inhale to perform cellular respiration.
The formula here requires inputs, otherwise known as reactants, to make ATP.
And oxygen is one of those reactants in the overall equation that is needed to break glucose
down in forming ATP.
Why ATP?
ATP stands for adenosine triphosphate.
It is action packed with three phosphates.
It has the ability to power many cellular processes.
Typically itâs coupled to other things that it may be powering.
Now after losing the phosphate, the molecule is ADP, adenosine diphosphate, because it
has 2 phosphates.
In cellular respiration though, there are enzymes that can add another phosphate to
it and convert it back into ATP again.
This particular formula of cellular respiration is aerobic, meaning overall, it requires oxygen.
It is pretty complex, and we have a video breaking down steps.
But thatâs not what this video is about.
This video is about what happens when there is no oxygen.
Because cells still need to make their ATP.
So what kind of cells can handle the no oxygen thing?
Well many types of bacteria can.
Many types of archaea.
Yeast, which is a fungus that could be helpful like making your bread rise.
Your muscle cells can, for a while anyway.
These are all just some examples.
Now these organisms handle the lack of oxygen in different ways.
Some organisms such as some types of bacteria or archaea can do anaerobic respiration---
they can continue to perform glycolysis, krebs, and the electron transport chain just like
aerobic cellular respiration.
But since there is no oxygen to be that final electron acceptor at the end of the electron
transport chain, they use something else.
Sulfate for example.
These organisms are specifically adapted to be able to use a different electron acceptor
in this anaerobic respiration.
Another option is the organism may just stick with doing just glycolysis, which doesnât
require oxygen, and then the addition of some way to get their NAD+ back----weâll talk
about what that means in a minute.
This process is called fermentation and thatâs what weâre going to focus on.
Fermentation is a way to be able to handle the little to no oxygen issue: it allows for
glycolysis to happen and for glycolysis to keep going.
That means making ATP when there is no oxygen.
And while you wonât make as much ATP in this process as you would aerobic cellular
respiration, you canât be too picky when oxygen isnât around.
Recall what glycolysis is from our cellular respiration video: in glycolysis, you take
glucose---a sugar---and it gets converted into pyruvate.
This takes a little ATP cost to actually start it up, but overall, you make 2 net ATP per
glucose molecule and you also produce 2 NADH.
Whatâs that?
Recall that NADH is a coenzyme and an electron carrier.
We also need to mention that NADH didnât just *poof* appear as a product.
No, because NAD+ actually was reduced to NADH when it gained electrons.
And if the words reduced and oxidized are confusingâŠyou can remember the famous LEO
GER mnemonic: Lose electrons= oxidized.
Gained electrons=reduced.
So NADHï NAD+ is oxidation because it loses electrons and NAD+ï NADH is reduction because
it gains electrons.
Now NADH, the electron carrier, would normally be delivering the electrons gained to the
electron transport chain if this was aerobic cellular respiration.
Once losing their electrons, NADH would be oxidized into NAD+ and be ready to be involved
all over again in glycolysis.
But thereâs no electron transport chain step in this fermentation process.
So weâve got to regenerate the NAD+ somehowâNAD+ is needed here after all for glycolysis to
continue.
Fermentation therefore adds another little step to the end of glycolysis---a step to
help regenerate NAD+.
This happens because fermentation allows NADH to give its electrons to an electron acceptor
which, in the two fermentation examples we are going to give, will either be a derivative
of pyruvate or pyruvate itself.
So here we go with two types of fermentation which both result in different products from
pyruvate.
Alcoholic fermentation: as done by some types of yeast.
So first glycolysis which yields 2 net ATP, 2 pyruvate, and 2 NADH.
Now we need the step to regenerate the NAD+ so we can keep doing glycolysis.
The 2 pyruvate is used which will ultimately produce carbon dioxide and 2 ethanol (alcohol),
but the derivative of pyruvate shown here, acetaldehyde, can act as an electron acceptor
in this process so that the 2 NADH can be oxidized to 2 NAD+ so that glycolysis can
start all over.
Since ethanol (alcohol) is a waste product in this process.Yeasts also can do alcoholic
fermentation in making bread, and the carbon dioxide product we mentioned is involved with
helping the bread rise!
The tiny amount of alcohol produced in the short fermenting time of bread will evaporate
in the baking process.
Lactic acid fermentation: as can be done by cells such as your muscle cells for example!
While your muscle cells can do aerobic cellular respiration, they can shift to lactic acid
fermentation if they experience an oxygen debt.
This could happen if you are working out very intensely where your blood is unable to deliver
a sufficient amount of oxygen to them for their demand.
Just like with alcoholic fermentation, we start with glycolysis that yields 2 net ATP,
2 pyruvate, and 2 NADH.
But now we need the step to regenerate the NAD+, and this step is a bit different from
alcoholic fermentation.
The 2 pyruvate on the reactant side will ultimately yield 2 lactate.
The pyruvate can act as an electron acceptor allowing NADH to be oxidized to NAD+ so that
glycolysis can start over.
By the way, this lactate product or specifically its other form lactic acid, has often been
blamed for the muscle soreness that occurs the day after intense exercise- in many of
my teaching years this was the hypothesis with this- but actually thereâs some recent
research that may dispute this product as the cause of muscle soreness.
Check out our further reading suggestions in our video details to learn more!
Lactic acid fermentation is also done by bacteria that are involved in making yogurt and lactic
acid can contribute to its sour taste.
So overall, fermentation is a pretty remarkable process.
Although, it does make us appreciate oxygen because despite how absolutely awesome fermentation
may beâŠ.âŠit just canât make as much ATP as aerobic cellular respiration.
Well, thatâs it for the Amoeba Sisters and we remind you to stay curious!
5.0 / 5 (0 votes)