[Music] [Music] good day Learners Welcome to our new lesson for today's video we're going to talk about the process on how plants create their own food plant leaves are the essential parts that can make food like a factory the leaves contain Machinery that can manufacture food out of raw materials and energy the important process of food making is called the photosynthesis which means to put together by light it is the most typical manufacturing process in the world and one of the most complicated process like a factory the leaves need raw materials to manufacture products raw materials for this process are carbon dioxide and water now these raw materials need the energy to make food the sunlight captured by the chlorophyll provides energy to combine carbon dioxide and water when the chlorophyll converts the raw materials they become glucose or sugar and oxygen photosynthesis is a chemical process which can explain by this General equation the raw materials are carbon dioxide plus water converted through light energy inside the chlorophyll and the product are glucose and oxygen now this is the balance equation of photosynthesis there are six molecules of carbon dioxide six molecules of water to form one molecule of glucose or sugar and six molecules of oxygen now there are two stages of photosynthesis the light dependent reaction and the light independent reaction where does the process of light dependent reaction begin light is the source of energy for photosynthesis and the first set of reaction which begin the process requires light thus it is named light reaction or light dependent reaction chloroplast capture sunlight in the light dependent reaction that takes place in the Grana light strikes chlorophyll or an accessory figment within a chloroplast it energizes electrons within that molecule chlorophyll and electron carriers are organized into units called photosystems when we say photosystem it is a functional and structure unit involved in photosynthetic reaction now there are three parts of photosystems the reaction Center which is a type of chlorophile that can absorb light energy and readily release in electron electron transport chain a series of electron carriers the antenna which is composed of chlorophyll figments that gathered and absorb light until it reaches the reaction center now there are two types of photo system photo system 1 and photos system 2 photos system one absorbs red light with with a wavelength of 700 nanom while photosystem 2 absorbs red light with a wavelength of 680 nanometer now there are two subp of light dependent reaction we have the cyclic light reaction and the noncyclic light reaction the cyclic light reaction starts with the photo system one where in p700 is activated to absorb light energy and release high energy electrons two poons from either the red or blue end of the spectrum fit the sensitive response of the figments they are captured by the antenna complex and transferred to the photosystem one reaction Center which contributes to high energy electrons to primary electron receptor they are passed to peroxin an iron containing protein which acts as electron carrier the second electron carrier which is plastocon carries the electrons to complex of two cytochromes in the process the energy pass along the surface of electron carriers lead to the ADP to ATP conversion the electrons are returned by PL the cyanine to the p700 pigment in the reaction Center to complete the cycle now let's proceed with noncyclic light reaction this reaction involves photo system one and photos system 2 but this time it begins with photos system 2 which is p680 it is activated to absorb light energy and release high energy El electrons poyan carry excited electrons from photos system 2 and dump them off at the plastocon the high energy electron also Cascade a series of electron carriers or electron transfer chain water splits into oxygen and hydrogen oxygen is released as oxygen gas which is one of the byproducts of photosynthesis on the other hand hydrogen ions temporarily stay within the tilid space and contribute to the hydrogen gradient chemiosmosis occurs as hydrogen ions flows down electrochemical gradient through ATP synthes compasses when we say chemiosmosis it is the process of diffusion of ions across a selectively permeable membrane low energy electrons living the electron transport system enter PS1 or photo system one when the photo system one pigment complex absorbs solar energy high energy electrons leave reaction Center chlorophyll and are captured by an electron acceptor light reenergize the electrons and they travel down a second electron transport shape hydrogen ions bond to nadp plus to form a more stable energy storage molecule which is the nadph nadph is energy and hydrogen atoms will be used to help build sugar in the second stage of photosynthesis when we say na dph it is sometimes called as hot hydrogen it is another high energy substance like ATP now for us to better understand the non-cyclic reaction I will show you an interactive simulation you can use this interactive simulation at the bioman biology site so here we're going to choose the light dependent reaction light dependent reaction happens inside the chloroplast specifically in the thid membrane now this is the thid membrane up close notice the location of the stroma and the thid space photolysis step one it happens when light strikes chlorophyll in the photosystem too remember I said a while ago that noncyclic reaction happens or begins at photosystem 2 this causes electrons to become excited or gain energy this excited electrons leave photosystem 2 and begin to travel down the protons of electron transport chain for photolysis step two water split to replace electron loss by photosystem 2 so because of the split of water it produces hydrogen ions and oxygen oxygen becomes the byproduct of the photosynthesis the excited electrons continue their Journey Down the electron transport chain as the electron travels down the chain their energy is used to pump hydrogen ions or protons across the membrane into the thid space this results in high concentration of hydrogen in the thid space and lower concentration in the stroma so as you can see there are a lot of hydrogen ions in the thid space that means it is a high concentration of hydrogen ions while low concentration in the stroma the hydrogen ion will naturally move from high to low concentration by the process of diffusion the only place on the membrane that lets hydrogen ions through is a protein called ATP synthes this ATP will be used during the Calvin cycle as an energy source to help produce sugar Calvin Cycle takes place in the stroma of the chloroplast so let's return to our electrons to and finish the journey that down the electron transfer chain the electron continues down the electron transfer chain to photo system one Light Strike to photo system one causing the electrons to get excited again these excited electrons then continue down a second electron transport chain the electrons are used to reduce nadp plus to form nadph nadph is also an electron carrier NPH carries the electrons to transport stroma where where they will be used in the Calvin cycle to make organic molecules like sugar so as you can see the product of the nine cyclic reaction proceed to the stroma where Calvin cycle happens now the overall product of light dependent reactions are ATP nadph and oxygen now we're going to discuss the light independent reaction or the Calvin cycle on our next video so that's it see you in our next lesson and if you are new to my Channel please don't forget to hit the Subscribe button and hit the Bell notification so that you will be notified for more videos like this