How does photosynthesis work you ask?
First, sunlight splits water into 2H+s, 2 electrons, and oxygen. Many, many water molecules split so there are lots of each of these inside and outside the thylakoid membrane. Oxygen will join with another oxygen to form O2 and will leave for us to breathe through the stomata of a plant. The H+s will move from the outside of the thylakoid to the inside through a transport protein that specializes in letting ions through (an ion channel). In order to get them inside, however, the transport protein needs energy to open. It gets the energy it needs to open from the electrons that are travelling through the electron transport chain. Once the H+s get through the ion channel, they are now on the inside of the thylakoid membrane. The concentration starts building up on the inside and the H+s need to get out in order to keep equilibrium within the chloroplast. When the H+s move through another channel to get out, the channel that they leave through is called the ATP synthetase pump. As the H+s move through back to the outside, they give their energy to the ADP and P that is waiting on the outside and this energy allows ATP to be formed (look back at your how to form ATP notes to refresh your memory on how this happens). This ATP will go to be used in the Calvin cycle where the Calvin cycle will break it apart and change it back to ADP and P and send it back to the light reactions.
Now, back to the electrons that are in the ETC, who are low on energy because they gave it to the transport protein to let the H+s through. These electrons go into an energy collection station (chlorophyll molecule) where the sun hits them and gives them more energy. They then travel through the ETC until they decide to leave through a transport protein and the electrons are bonded to NADP+ and H+ that are on the outside of the thylakoid to form NADPH. NADPH goes to the Calvin cycle where the Calvin cycle will break it apart and change it back to NADP+ and H+ and send it back to the light reactions.
The dark reactions are way more complicated because they utilize carbon dioxide and ATP and NADPH to make sugar, but if you want me to go over it with you, then leave me a comment here by clicking on where it says how many comments there are at the end of a post and it will let you type in whatever you have to say.
I hope this helps. If you need a visual to go with it, try Google imaging "thylakoid membrane" or "light reactions" and see what comes up. Use it with the text written here and go from there. Enjoy your extra hour and I'll see you tomorrow! The good Doctor
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3 comments:
hey dr r-
muchas gracias for that study session! it cleared up a lot of my questions
but i didn't take very good notes on one section - what exactly happens to the carbon chains when they want to get into the krebs cycle??? i had a really hard time understanding that in the packet, too.
haha when i first came to the page i thought the title said "reach for it with rasin."
anyway thanks for that study session!
emily dv
Hey Emily! The pyruvic acids (3 carbon sugars) can't get into the Krebs Cycle because the mitochondria doesn't let them come in. The first thing they do is release a carbon dioxide molecule as a waste product (CO2). The pyruvic acid now only has two carbons and is called an acetyl group. It tries to go back to the mitochondria but the mitochondria still won't let it into the matrix so it finds a molecule called Coenzyme A or CoA for short. The CoA will change the shape of the acetyl group so it can get in to the Krebs Cycle.
Try looking at the sentence in the Krebs Cycle (#1) that says something like the two molecules that are broken down in glycolysis called pyruvic acid, go to the mitochondria, are rearranged by acetyl CoA and enter the Krebs Cycle.
So the Krebs cycle starts with acetyl CoA and will make ATP, NADH, and release more CO2 as a waste product.
See if this helps. If it does, great. If not, ask me some questions on it tomorrow! Take care and thanks for coming to get help!! Have a good night! Dr. Rosin
Hey Mrs. Rosin
Alright, i know that we cramed alot of stuff in today after school but going back and reveiwing some of the things in my notes, i wasnt sure about some things that were put down.
- Why does celluear respiration even accure and how do you know if your using celluar respiration?
* that might be a really stupid question but my mind all the sudden blocked...
also..
- I was reading the first problem on osmosis you gave us reading... " A cell is placed in a hypertonic solution . What will happen? and our class answer was nothing. I dont really understand why because one has alot of particles and less water and the other have alot of water and less partciles.. so how does nothing happen? Do they just like...cancell eachother out?
and i was wondering if we can go over one osmosis problem before the test tommorow because the one with o.5 M of NaCl and 1 M or glucose is tricky....
:]]] thanks very much
have a good night
Jacki
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