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Biology Lesson 02.06 Introduction to Photosynthesis
Transcript of Biology Lesson 02.06 Introduction to Photosynthesis
Introduction to Photosynthesis Thylakoids are membranous disk-like structures that are stacked together in larger structures called grana. When I hear the word Thylakoids I think of a stack of coins! In this stack, is where photosynthesis takes place. The next day, Cindy was ready to keep on the tour. So She went out to find Wendy and they continued. "So where did we leave off yesterday? Oh yes I remember. It is your job as a glucose molecule to stay in the plant." All of a sudden....
"Thump, Thump, Thump!" The sirens went off again. The tulip was shaking. "Oh no is it another storm?" Cindy cried. "No this is an....
"RABBIT! RUNN!" everyone screamed. "Well there was no place to run, then I saw it, I saw the rabbit and it's huge mouth!" Cindy taught in her mind. "AHHHH" Cindy yelled! It became dark, Wendy shouted, "Cindy follow me, we need to get to the cytoplasm of the animal cell! Hurry!" Cindy said" Alright I am here, where do we go?" Wendy grabbed Cindy and they both rushed to the cytoplasm. Since Cindy is now apart of a glucose molecule she has to travel together with the other 5 carbon molecules. Wendy begins to speak: "Fellow glucose molecule members, we have a new member so I will be giving the explanation all the processes.
By: Cindy Rajkumar Images from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission. The photograph below is an elodea leaf X 400. Individual cells are clearly visible. The tiny green structures within the cells are chloroplasts. (awesome) Chloroplasts absorbs light because it contains chlorophyll All organisms require energy for their chemical reactions. These reactions may be involved with:
3. Other activities.
Photosynthetic organisms (such as plants) use light energy to produce carbohydrate (glucose). Glucose can be used later to supply energy that the cell needs. Photosynthesis is therefore a process in which the energy in sunlight is stored in the bonds of glucose for later use. Our Journey Begins: Hello there my name is Cindy the Carbon Atom and today will share you my experience on the first day on the job. My boss had given me a special task of experiencing photosynthesis. She showed me a video explaining everything. My first goal was to get/be part of a glucose molecule. Then my boss said she would meet me once I reach that check point, and explain how I did. So lets begin! ....However, right when we were about to leave, a storm was on its way! Horns and sirens were making noises everywhere! The atoms were scattering all about.
It was a very windy day, the leaves were blowing, the clouds were moving and even the trees were trembling. My friends have all scattered about looking for shelter. "Come quickly Cindy" Carbon Megan shouted. "Hurry up, or you will get stuck or even blown away" said Oxygen Alex, worriedly. Cindy was trying to move to the other side of the garden but the wind blew her in the opposite way. She kicked and turned but there was no one in sight that would dare to help her in the winds they call "Dangerous May." She flew and rolled and finally stopped on tulip flower that swayed and swayed. Cindy so tired, could not get up, so she was forced to stay. She fell asleep for many, many days.
When she woke up it was bright as can be, sunlight and flowers bloom 1, 2 and 3. All of a sudden gust of wind pushed her down to the flowers leaf. She took a leap and down she went, deep into the leaf, here she will start vegetation. Carbon is a gas, this is the only way she can enter the process. "Wow" Cindy says there are atoms everywhere, she looked left and right where atoms did their job. Finally she saw a place that looked familiar from the video, the chloroplast, this is where photosynthesis takes place. "Who is in charge" I asked one of the fellow atoms. "Hello there welcome to your new home! My name is Water Wanda, I help guide the New-B's, its part of my internship." she said. She started walking and talking, and Cindy Followed. "You are at the chloroplast, here are the thylakoids (pointing at stacks). The thylakoids are a huge part of photosynthesis because it is where it takes place. Do you remember?" "Yes I do" Cindy replied. "Great lets move on. So on the video you learned what light dependent reactions were, right? Come follow me, we will go experience the reactions!"
Cindy: AHHHH! Cindy Was so scared, not knowing what would happen. They both walked toward the stacks, all of a sudden Cindy felt warmth. It was the sunlight coming in! Cindy saw molecules moving all around. "When the chlorophyll molecules absorb sunlight, they give off high-energy electrons. The electrons move through a series of electron carrier proteins, called the electron transport chains, within the thylakoid membrane." The electron and hydrogen ion is accepted to be NADP+.
"NADPH can carry these high-energy electrons to another molecule and transfer them, along with most of their stored energy. To repeat this series of reactions, the electrons and hydrogen ions must be replaced.
An enzyme will remove electrons from the water molecules and give them to the chlorophyll. When this happens the water molecules split: oxygen molecules and hydrogen ions.
These hydrogen ions and chlorophyll are used in future cycles of the light-dependent reactions. Oxygen molecules are released into the air as a product of the photosynthesis reaction!" She said.
"Wow! this is so cool!" Cindy saw the whole process right in front of her eyes!
Light Dependent Reactions: Light Independent Reactions: "Great job in learning about dependent reactions, now lets look at independent reactions!" Wendy said. Cindy was so excited!
"The light-independent reactions are the 2nd set of reactions in photosynthesis. They are often referred to as the Calvin cycle!" Cindy replied. "That's very true! Carbon dioxide molecules enter this reaction from the atmosphere. An enzyme in the chloroplast combines the carbon dioxide molecules with other carbon-based molecules that are already present inside the organelle."
This forms three-carbon compounds. Cindy looked so amazed.
Every 12 - three-carbon molecules made, two are removed to build organic compounds. The other 10 continue on in the cycle. The two three-carbon molecules that are removed bond together, forming a six-carbon sugar such as glucose!
Fantastic! You have completed the cycle of photosynthesis! You learned that there are 3 reactants: Carbon dioxide, water and sun energy! The 2 products that are made during photosynthesis are oxygen and glucose! But get ready tomorrow will be a long day! Day 2 The first one is Glycolysis, it is anaerobic - (does not require oxygen). Glycolysis splits glucose, a 6-carbon compound, into two 3-carbon pyruvate molecules. So we as the carbon molecules had to split. We all then moved to the mitochondria. The first step went by quickly Cindy wondered.
"Alright everyone, we are here, welcome! This is where the Krebs cycle takes place. This cycle is aerobic - (requires oxygen).
1. At the start of the cycle, an "acetyl" group combines with a four-carbon molecule called oxaloacetate to yield a six-carbon compound.
2. Then the compound is stripped of two of its carbon atoms, which are given off in the form of carbon dioxide. High energy electrons also are released. These travel to the electron transport chain, where they produce energy in the form of an energy-rich molecule called adenosine triphosphate, or ATP. Unforunately, Cindy and fellow carbon molecules, you cannot come, but I will still explain the next steps for you.
The third step is the electron transport chain, which is aerobic - (require oxygen). We will have to travel inside the cell's mitochondria. In this stage we use the high electrons from the other stages to produce more ATP. This stage produces significantly more ATP than any other stage of cellular respiration. This stage requires oxygen, and that oxygen and hydrogen is used to make water molecules. That is about it for the 3rd stage in cellular respiration.
"For you carbon molecules your job is complete for now, bye you guys!." said Wendy
After the other molecules move on to their next step, we the carbon stayed. We waited and then the rabbit started to move, its jumping up and down. We were tossed all around. Cindy felt that the rabbit is now tired, because it is breathing heavily, A gust of air coming in to the rabbit, and I was pushed out! "Yay, I'm out. Wow that was so cool! Lets do it again!" Cindy said! Cindy now realizes that the process is one big cycle. Photosynthesis and cellular respiration work together to "support life on earth." (FLVs) Cindy notices that
Photosynthesis: uses energy, water, and carbon dioxide to make glucose and oxygen.
Cellular respiration: uses glucose and oxygen to make energy, water, and carbon dioxide.
They both use each other's reactants, to complete the cycle! A Job well Learned! :) Citation:
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