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Photosynthesis_from Sciencefreaks_1

Added Oct 29, 2012 •

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welcome to the first video lecture for chapter 7 the light reaction of photosynthesis first let's take a look to see how scientists figured out this process even tested the year is 1771 chemist Joseph Priestley conducts a series of experiments to see what happens when he Heats various substances and close jars and collection and gases not in one of these pyramids he put a lit candle under the jar  but the flame quickly burned out please please words the air inside was injured  curious what effect this injured air might have on a living he placed a mint leaf inside the jar and left it there for 10 days when Priestley check back the leaf was still green somehow the air inside the jar was fresh again  priest speculated that the mint leaf must be responsible for the transformation  but how  this question unanswered until a Dutch scientist named John ingenhousz decided to duplicate priestley's experiment  using plants how to witness the same beguiling phenomena  after conducting a series of more tests singing house began to realize what was happening the ability of a plan to transform the air inside the jar only work if the plant was exposed to sunlight  this was the Breakthrough together Priestley and ingenhousz had discovered photosynthesis the biochemical process by which plants trap the energy of sun and convert it into chemical energy  photosynthesis removes carbon dioxide from the atmosphere and what is it with the gas on which our survival depends oxygen the same gas did Joseph Priestley would discover 3 years later 1774  try to get you some history behind the process of synthesis in our understanding of it and since we know the plants don't eat their fruit as shown in this animation here we're going to look at how they actually make best food first of all though let's start with the structure of a leaf where photosynthesis occurs you do need to be familiar with the fact that many plants waxy coating called the cuticle which helps prevent water loss the lower epidermis also has structures called stomata or stoma singular term was introduced in the animal versus plant cell glad you perform during chapters 4 and 5 so you should be familiar with it at least as an introduction stomata are openings that allow for gas exchange and water loss remember transpiration occurs and stomata can open and close depending on start mental conditions the plant is in it gets too hot and the plant needs to conserve water the stomata will close if it's cooling up the plant needs to get carbon site for photosynthesis the stomata will open  also noticed there are two different types of mesophyll cells the Palisade mesophyll cells I'm all rectangular and are found along the upper epidermis the spongy mesophyll cells are more circular and I located next to the lower epidermis the spongy mesophyll cells being circular shaped have more air spaces surrounding them fill out that gas exchange when the stomata are open it will look more closely at the structure are the chloroplasts found in each one of these cells very soon you also need to know that there are pigments involved in photosynthesis found in the chloroplast of plant cells pigments absorb light of certain wavelengths and reflect light of other wavelengths and you should know what color the pigment reflex how do you know that well just by looking at that remember if an object looks red to us it is or being all colors but red red is reflected back which why we see it as read that absorb all colors except mostly green how do we know that well which was reflected back you need to know chlorophyll a and Chlorophyll B those green lines violets blues and reds carotenoids which include xanthophylls and carotene absorb violets and blues when you can see this absorption Spectrum graph on the left notice their higher when they absorb that color  the action Spectrum graph on the right shows under what wavelength of light plants are actively photosynthesizing all of them except really the green which can should make sense when we perform on some salad greens and lab for you actually be able to see these different pigments separated on paper  Festival Yuma learn this equation coefficients included 6 CO2 + 12 H2O yields C6 h-12 o-6 + 602 + H2O  okay you need to know that equation now if you take off the 6 H2O on the right at the product you could write it 6 CO2 + 6 H2O yields C6 h-12 o-6 + 602 you can write it either way but you need to know one of those equations  now here's a quick overview of photosynthesis superimpose on a core class so we can kill two birds with one stone getting an overview and looking at the structure of a chloroplast so let's focus on the structure what country or plast have the double membrane its own DNA and ribosomes leaving scientists to populate the endosymbiotic hypothesis you should know this by now chloroplasts or ones photosynthetic prokaryotic organisms engulfed by larger cells and then converted to organelles in that sell the liquid space inside is called stroma not stoma or stomata and there's an are in there so stroma it's analogous to The Matrix of the matter yeah and then the intermembrane with folded into stacks of flattened deaths each disc is a thylakoid and a stack of thylakoids is a granum girl is Grandma so just like in mitochondria the two phases of photosynthesis occur in two separate locations the first in the thylakoid membrane that can stroma this diagram is a diagram we looked at on Friday or similar to it on the back of your cellular respiration diagram and this lecture we will be focusing call me on the light reactions which occur in the thylakoid membranes and generate oxygen as a waste product and ATP and nadph and let's get started the first stage of photosynthesis is called the light reactions because it requires light to occur that makes sense without the input of energy from fun or synthetic light sources this reaction would never occur in photosynthesis would not happen in the membrane of each and every file Aqua desk and each and every quarter plant cell and this is a familiar to you what does it remind you of well it should be processed we just learned about and cellular respiration the electron sport chain yep it occurs in chloroplasts to light energy comes in and is absorbed by pigments mostly chlorophyll a but Chlorophyll B and coins accessory pigments they help as well the energy from the light is absorbed by electrons which are shot out of the pigment complex to move bumpity bumpity bump TC has the electrons are passed from protein protein including cytochrome all is well here they lose energy which is used to hydrogen ions into the thylakoid membrane ateneo's modded gradient is created and the hydrogen ions can flow passively back out through an ATP synthase enzyme free dating app that is all known as photosystem 2 photosystem 1 has a pigment complex that also absorbs light energy injecting but just electron is picked up by an nadp plus molecule along with a hydrogen ion to reduce it to nadph no this electron carrier molecule is different than the ones used in the mitochondria this one has a p in it and you can remember photosynthesis starts with a so the electron carrier molecule has a p in ADP plus becomes nadph carrier molecule and cell respiration was NAD plus becoming nadh so nadp plus becoming nadph in photosynthesis how come both of them to doesn't run out of electrons if they are picked up by nadp plus wow this is why a plant needs water a water molecule is walking down to the practice of otologist into hydrogen ion used to make ATP oxygen released by the plant and briefs and by us electrons which are accepted by the pigment complex and will move through the electron transport chain let's take another look at a picture of this prophet so remember this is photosystem 2 on the left light comes in energized electrons bumps it up and down the transport chain producing ATP goes to photosystem 1 again except light energy and is ejected up and instead of moving to the electron car chain is picked up by any DP plus becoming nadph both ATP and nadph will move on to the dark reaction which about in the next video lecture  remember you need to know the name of the process that breaks down water called the tallest you need to know that the production ATP in the light reaction is called photophosphorylation so nice big word photo means light phosphorylation is adding phosphate tell molecule cell photophosphorylation using light energy to make ATP you also need to understand this is only one path in the light reaction it is known as the non cyclic pathway the electrons are picked up by the nadp plus molecule and that are not returned to the vigna complex and include photosystem 2 and photosystem 1 now moving on there's also a cyclic pathway in the light reaction of photosynthesis show me photos of someone is involved in this pathway electrons absorb light energy and are ejected out of the reaction Center to move down the electron transport chain ATP synthase and producing ATP once the electrons are shuttle from protein to protein bumpity bumpity bump they can actually be returned to the picnic complex of photosystem 1 used hence the cyclic pathway now let's watch a video that will animate both of these Pathways four hours in bacterial photosynthesis a single photo system is involved when an electron is energized by absorption of light it is ejected from the photo to reaction Center the electron passes down through an electron transport system and finally back to the reaction Center the energy released during this electron transport is used to produce ATP since the excited electron returns to the Confederate this mechanism for making ATP is called cyclic photophosphorylation no reducing power needed for biosynthesis is generate in this process plants and cyanobacteria utilize two photosystems which work sequentially to produce both Ed reducing power first a photon of light ejects a high-energy electron from photosystem 2 the electrons lost from photosystem who does not return to photosystem II but is replaced by an electron generated from the enzymatic splitting of water and the release of oxygen the electron been travels from the excited reaction Center of photosystem 2 down an electron transport chain and finally to the reaction Center of photosystem system one  list electron transport system generates a proton motive force that is used to produce a repeat  simply excited electron does not return to photosystem II this mechanism for making ATP is called non cyclic phosphorylation when photosystem 1 absorbs a photon of light it ejects the high-energy electron which is used to drive the formation of reduce power in the form of nadph the injected electron is replaced by an electron from photosystem 2 one thing to notice is it goes a little backwards what's the temp to comes before photosystem 1 and the reason for that is photosystem 1 was discovered before photosystem 2 who even though it backward to us it's the named in the order in which they were discovered so make sure you get that right probably all you know about photos of them from your fourth grade science class plants take sunlight water and carbon dioxide and make oxygen and sugar that's not going to cut it for AP biology this and actually disease scheme diagram that is what you'll be quizzed over that's what you need to know about the light reactions consists of two photosystems in the thylakoid membranes the noncyclic pathway includes both photosystem 2 and 1 and produces ATP and nadph electrons are added through photos of the breaking down of water the ATP is produced through chemiosmosis result of the electron transport chain the cyclic pathway includes only photosystem 1 and produces only ATP cute and we're going to look at the reaction on the next video lecture so we're going to say that  congratulations you've reached the end of the first video lecture for chapter 7 see you on the

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