Conceptual overview of light dependent reactions
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- Опубліковано 23 чер 2016
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Seeing how light energy can excite electrons which can be used to create ATP and NADPH (with oxygen as a byproduct).
What an enLIGHTening video
Zachary Watkins y/angryupvote
Ba dum tsss!
Am I the only person who enjoys puns and dad jokes ?
@@themadladprince430 no
@@themadladprince430 no
THIS VIDEO FINALLY MADE ME UNDERSTAND THE LESSON. NEVER UNDERSTOOD IT FROM MY TEACHER
BRO SAME HAH
Same here
Same here
I learned photosynthesis 30 years ago in college, from a botanist who was researching photosynthesis--Stephen Herbert. His teaching diagrams and commentary were so much like this one--focusing on the dynamics of forces and gradients. Like Diana Rogava says below, the amazing action of how oxygen gets split away from the water is not really explained by most instructors. They are too focused on naming everything--and aren't seeing the big driving forces and the recovery methods. These 2-bit instructors (1 of them was head of my whole biology department) didn't comprehend how hugely, dangerously powerful the photons are, and didn't understand that the photon drives an electron into a crazed hyperactive condition, causing the electron to leave behind a huge negativity when it exits. This enables Chlorophyll 680 to do an otherwise impossible oxidation of the tightly-bound water molecule--it rips off the oxygen so it can regain an electron for the next excitation. The H+ in the meantime accumulates, providing for gradients that cause photosynthesis to continue. And there is another type of pigment that is usually present in Photosystem II, carotenes, that detoxify the photon's radiation damage to lipids in the surrounding membrane. As you can see, the antioxidants important in your diet are crucial to the plant, too.
I learned photosynthesis from Lee Van Cleef, during his brief spell as a Biology lecturer. I have doubts about his understanding of any of the mechanisms. He never really explained the hydrogen ion gradients and instead spent most of the lectures sneering and practising shooting tin cans off a fence.
Nice summary, well described.
I had a test today on this. Studying this overnight helped me out a ton. Thank you.
this video cleared all of my 3 years confusions about photosynthesis in just a few minutes omg
The different complexity levels really helped me to wrap my head around the topic :)
this is so clear oh my gosh thank you thank you thank youuu!!
So incredible helpful! Sal you are a Saint to me! May God bless you and keep you!
thanks dude.. now i can help many other to learn photophosphorylation .
I could not find a video that actually explained this properly, finally stumbled upon this!
great video sir thank you!
Finally ...awsome xplanation..for my son to understand . Thank you.
Time to change district :)
I never understood why water was split into oxygen and hydrogen! Now I do! thank you very much
this video was neat and clean than the previous light rxn video lol
Really excellent overview. The mechanism of making oxygen from water was well stated as were the other focus points.
I love you. Thank you.
Is there a video that explains the alternative Cyclic Electron Flow if there isn't enough NADP + available?
this is so helpful! thanks sm!!
It is so helpful👍!I am referring why was I not here earlier!😦
Is Hidrogen ions that pump out from ATP sintase that can form ATP is the same ion to produce NADPH in light reaction? Or it's just pump out to the stroma to balance the centration of H ions outside and inside the membrane?
I owe you alot
Gracias
khan academy the real G😀😀
OMG now it all makes sense
Why do we have two equations for photolysis?
H2O → 2H+ + 2e- + ½O2
Or
2H2O → 4H+ + 4e- + O2
How many electrons move into photosystem 1, 2 or 4?
thanks cousin sal
I never thought Biochemistry is this easy!
Ok. What will happen in winter, when there are no leaf?
Green stems n stored food
Wow 🥳🥳woohoo..! Its utopia..you really drove me inside the leaf ...and I saw the process was so real. But I wanted to know who took you inside the leaves that u understood and make us comprehend so well. 👨🏫BEGGER DESCRIPTION..!
ありがとございます
すごい
If photons are absorb by both the photosystems then why do photosystem 1 exites first and donates electron?
do you mean photosystem 2 exites first?
Because PS 2 can Only donate electrons by breaking water !!! PS 1 only transfer it's 1st electron then it need electron from ps2
@@evolvedone3493 what electrons in PS 1 get excited ? The donated ones or the original ones?
Just a personal bookmark
7:00
I'm struggling.
What I want is an answer to how chlorophyll converts light energy into matter.
Learned this in college 35 years ago.
Now someone in chat has told me there is no such equation, chlorophyll doesn't do that.
So i'm googling and reading .,.. to prove them wrong. [insert evil laugh]
Been thru 3 videos so far, they just vaguely talk about "light energy". Not enough.
I'm still watching yours, but struggling.
2:46 What is ATP? I know you mentioned this, but I don't understand.
Now there's an "H plus gradient" and I give up.
I think you're talking about what I want, but its not enough.
You might consider breaking each of these steps into vids you can play picture within picture for those of us who need more hand-holding. The squiggly shapes of your hand drawn features aren't reassuring.
I'll keep looking for a video that fits what I want.
Thanks for a good start on my search, however.
I'm just cramming for an exam so take this with a lot of salt but here's what I know that might help you:
The light energy (photons) help catalyze H2O to split into oxygen gas, protons (H plus), and electrons.
Those electrons go through the photosystems, and essentially the outcome of their journey is to oxidize NADP into NADPH, an electron carrier (that gets used later on to power the Calvin cycle)
Those protons/H+ (same thing) form the "H plus gradient." That gradient powers ATP synthase (almost like a hydroelectric dam, there might be a good animation online to help a bit with explaining how the H+ gradient powers ATP synthase.) The end result of that is ATP, which is a really important molecule in biology more broadly. Those are the processes that this video covers.
The important thing that answers your question is that light energy is turned into chemical energy (aka ATP and NADPH), and that chemical energy is used to power important processes in life. In photosynthesis, you have 2 main processes: the light reactions (which is what this video covers, light to chemical energy) and the Calvin cycle (which isn't covered). The Calvin cycle uses CO2 and the chemical energy (ATP and NADPH) made in the light reactions to make glucose. Glucose gets broken down in cellular respiration (which is a whole different concept) to make ATP that's used to power processes in the cell.
My bio professor compared ATP like a dollar: it's practically the currency in cells to make things happen. That's where light energy turns into a tangible, important resource.
(Photosythensis overall equation)
6CO2 + 6H2O + light → C6H12O6 + 6O2
Count up all of the carbons, oxygens, and hydrogens: no atoms were created. The light (overall) helped to change the form of the molecules.
(Cellular respiration overall equation)
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP
Notice that out of those two equations, the net outcome is that light → ATP (which is life's currency for energy). While light energy doesn't turn into matter essentially, it turns into chemical energy which allows pre-existing matter to be manipulated, resources to get transported, and overall multicellular life to exist. I'm just studying photosynthesis right now, but there's a ton of resources out there that could help better explain what ATP does in the cell if you're interested! Hope this helped, I'd verify any technical info with someone else because I'm iffy on the subject too :)
i’m here 2 days before the exam 🤭🤭
l
grrr...why can't all biology teachers teach the same!