C4 CYCLE

• Photosynthesis: Light-...
^ Photosynthesis
Why do C3 plants, such as wheat, thrive in climates that are wet and cold, while C4 plants, such as maize, have the advantage in hotter, drier climates?
Well, as mentioned in this video, RuBisCo sometimes binds oxygen instead of carbon dioxide. This wasteful alternative pathway is called photorespiration.
Here’s a brief overview of RuBisCo’s actions:
In the Calvin cycle, CO2 is combined with RuBP to form two PGAs. Upon the completion of 6 rounds of this cycle, one glucose molecule can be produced.
Sometimes, however, RuBisCo picks up oxygen instead. This results in photorespiration. The oxygen is combined with RuBP and creates only one PGA, as well as phosphoglycolate, a two carbon molecule that is toxic to plants. This is why photorespiration is sometimes called the C2 cycle.
Following the creation of phosphoglycolate, the plant attempts to reduce negative consequences, and is forced to use up precious ATP and NADPH that was created during the light-dependent reactions.
As a result, photorespiration decreases the net CO2 converted to sugars and decreases the plant’s growth rate.
To minimize photorespiration, plants need to keep oxygen concentrations low in their leaves. Plants accomplish this by keeping their stomata open.
Stomata are pores in the leaf epidermis that facilitate gas exchange. This is how oxygen leaves and CO2 enters. However, open stomata also result in a process called transpiration.
Transpiration is the movement of water through the plant and its subsequent evaporation.
Most of the water taken up by a plant’s roots is lost in this fashion. Stomata are more numerous on the undersides of leaves to limit this.
Transpiration isn’t totally a bad thing, as evaporation of water from exposed plant surfaces results in water rising from the roots, thanks to an osmotic process called transpiration pull, allowing for mass flow of mineral nutrients along coming along with the water.
In a cold, wet climate, where water loss isn’t as much of a concern, keeping stomata open isn’t a problem. Here, C3 plants thrive.
However, in hotter, drier climates, where water loss through transpiration is less affordable, C4 plants have the advantage. Here, it is worth investing into an adaptation called “Kranz Anatomy. This adaptation, while inefficient in a cold, wet climate, allows these plants to flourish in harsher conditions. Let’s compare a cross section of a C3 and C4 plant leaf.
Both have an upper and lower epidermis, as well as stomata. C3 plants have two types of mesophyll cells that carry out different functions: palisade mesophyll cells, and spongy mesophyll cells. Meanwhile, C4 plants don’t have this specialization. Both C3 and C4 plants have bundle sheath cells, which surround the vascular bundles.
In this video, we shall focus on how the C4 anatomy counters the problem of photorespiration.
Let’s look at the C4 pathway, also called the HSK or hatch slack kortshak pathway.
Again, this pathway takes place in C4 plants, specifically in the mesophyll and bundle sheath cells. Let’s zoom in on these cells. The reactions take place within their chloroplasts.
We start off in the chloroplast of the mesophyll cell, with PEPA, or phosphoenolpyruvate, which is a three carbon molecule, CO2, and PEP Carboxylase. PEP carboxylase adds the CO2 onto the PEPA, and the result is OAA, or oxaloacetate. This is the first stable compound in the pathway. It has 4 carbons, and this is why this pathway is called the C4 cycle. You may recall that the first stable compound in the C3, or Calvin, cycle is 3 carbons.
Next, the reducing agent NADPH2 comes in and reduces OAA to Malic Acid. Malic Acid then travels to the chloroplast of the bundle sheath cell, where a decarboxylase removes the CO2. This is the plant’s ultimate agenda, for now, within the chloroplasts of the bundle sheath cells, so carefully guarded from the presence of oxygen by the concentric ring of mesophyll cells surrounding them, RuBisCo is flooded with basically pure CO2, with no oxygen to confuse it. The CO2 enters the Calvin cycle within the chloroplasts of the bundle sheath cells, and the C4 plant has successfully bypassed photorespiration!
Pyruvic acid is the three carbon compound that remains after the CO2 is stripped off of Malic acid. It diffuses back into the chloroplast of the mesophyll cell. Here, ATP phosphorylates it, turning it back into the original compound, PEPA.
Credits: Video Copilot textures

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Excellent explanation! If the schools start teaching like this then the students will never loose interest in their studies and fail in examination. Hats off to your efforts. Thank you so much!!!

[@NeuralAcademy]

Aww, thank you so much ^_^ ^_^ ^_^

[@mahimai8992]

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[@Polarcupcheck]

You have not the slightest clue what the term "Title I" means.

[@vivekguatam1551]

Best C4 cycle explanation video available on youtube. Not only it covers the C4 cycle in the end but also covers the basic topics required to understand the video properly. The way the creator explained why the C4 cycle occurs in a hot & harsh climate is also applaudable. Thanks to the creator for such an amazing video.

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[@dematerializedtower]

This might be the best explanation of C4 plants! I'm not confused anymore, thank you so much

[@shaikrehanaparveen8862]

Wonderful Animation with simple explanation. Brilliant

[@bs4021]

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[@nuredinmohammed282]

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[@tusharsingh1699]

Very nicely done! Thanks

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It has clear my doubts .

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N nice animated

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Wow.
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Best animated for c4.. i loved it😇

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nicely explained :)

[@GOODVIBES-js5mi]

very helpful video thank you.....

[@aynoor552]

How Bundle sheeth cell gets ATP for dark rxn?

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[@Kamal-ho2qh]

Impressed 👍🏻

[@hemishamadhow5033]

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[@gunamuthu3761]

Best video on this topic

[@sushsharma5418]

Why is OAA reduced to malic acid??

[@naturevibes-hg3jc]

Superb explanation..🖤...🖤...🖤..🖤..

[@ImranHussain-so6zz]

Wonderful

[@syedfawadalam3425]

Nice explanation

[@shanzay8686]

Why there is no oxygen in the chloroplast of bundle sheath cell???

[@s.sambath2202]

excellent

[@sherlypaul9791]

Wheat is a monocot and hence it does not have a differentiation in mesophyll like palisade and spongy parenchyma but still it's C 3 why???

[@andrewbickford2644]

very cool stomata

[@anjanarajan1853]

Nice video

[@lohithbeerappaheggadev.ssh5481]

Super 👌👌

[@primordial7305]

Thank you. Know that this helped a student pass his test.

[@Frankie_1908]

I understand the process, but what does this have to do with climate?

[@user-se3rp4cz8w]

C4 plants can grow in dry climatic conditions

[@haylynshon7514]

In calvin cycle 3 molecules of CO2 are used resulting in 1 pgal but to make 1 molecule of glucose 2 phal are needed which means to make 2 pgal 2 cycles of Calvin cycle will be needed isnt it?

[@user-se3rp4cz8w]

No

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[@sahidaakhtar4225]

Thank ya '❤️

[@MANISHKUMAR-uw3dz]

good

[@jarvischam6930]

I think photorespiration forms 2 phosphoglycolate, not 1 phosphoglycolate

[@andrewmontoya8511]

stomata making me act up

[@vOID-no1pi]

💀😆

[@yussuphmbaroukalliy8669]

If 1molecule of CO2 is equivalent to 5 Molecule of Atp, so for 6CO2 molecule it's for 30 total molecule of Atap how about 2molecule of atp for 1 molecule of Co2 used to regenerate pep to recycle again

[@NeuralAcademy]

The point of the C4 cycle is to create glucose, which then goes into Kreb's cycle to make ATP. During Kreb's cycle, the yield from 1 glucose molecule (2 pyruvate molecules) is 6 NADH, 2 FADH2, and 2 ATP.
Back to the C4 cycle - ATP is needed to recycle RuBP. One glucose molecule requires 6 CO2 to be built via 6 rounds of the C4 cycle. So lots of ATP ends up being used up in this process.

[@ImranHussain-so6zz]

But How water loss reduce

[@deeppatel1979]

Nyc

[@dixitadhiman1701]

❣️

[@nehanikam4550]

nice

[@nlinganna531]

Nice video mam

[@gourimali9921]

Then where the food is produced? In the cycle

[@learnbiobytricks2335]

Glucose is the main food which plants prepare so glucose is produced in bundl sheath cell in c4 plants and in mesophyll cell in c3 plants

[@Geeth88054]

Good

[@waseemmaqbool822]

Madam can you please make video on Etc

[@NeuralAcademy]

Electron transport chain? In the C3 Cycle? I have one :-) th-cam.com/video/DlZh_Gzb7tI/w-d-xo.html

[@waseemmaqbool822]

Neural Academy ..yes

[@waseemmaqbool822]

The link has light and dark reaction
explained in a best way ever but I wanted to know how NADH2 and FADH2 are oxidised to release the energy stored in them in form of ATP in the inner mitochondrial membrane

[@NeuralAcademy]

Well, I guess I'll have to make another video then! :-)

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Now I'm confused

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Sub-seek-went?

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I learn more !!!

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[@home7870]

Just say about c4

[@ganeshjoshi2793]

PEP(Phospho-enol pyruvic )u wrote wrong spelling 😅😅

[@yussuphmbaroukalliy8669]

I can't understand the total of atp used in c4 plant

[@tusharsingh1699]

There are 2 atp used in this cycle ...ATP converted into AMP .. regarded as 2 atp used

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lol

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