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Intro to Cellular Respiration
Photosynthesis and Cellular Respiration compliment each other perfectly
-The reactants of one are the products of the other and the products of one are the reactants of the other
Remember our formulas for endergonic and exergonic reactions?
Are they starting to make more sense now?
In order for cells to function and for metabolic reactions to continue a cell needs a continuous supply of chemical energy.
-That chemical energy is in the form of ATP
-The Mitochondria makes all the ATP for a cells metabolic processes
Glucose is a key energy-storage molecule
-Glycogen (Long chains of glucose)
-Fat
Everyone is going to come to the white board at the same time and write an answer to these questions. Answer the first question then sit back down. We will discuss the answers as a class then come up and answer the next question.
-What does the human body need?
-What does cellular respiration need in order to function
-What is the main function of the respiratory system?
-What is the function of your heart?
-Why do we die as soon as the heart stops?
-Why do we need to breath?
-What do fish breath?
Time for some exercise!
-We need a team of three
-One person is going to hop up and down continuously
-One person is going to read that person's pulse and oxygen percentage
-The third person is going to write the data on the board
-The rest of the class is going to write down the results
-We will then graph the results and analyze them
Glucose Breakdown
-The first stage in glucose breakdown is Glycolysis
-Glyco which is Greek for sweet and Lysis Greek for to split
-Glycolysis is the splitting of glucose
-Glucose is a 6 carbon sugar it is split into two pyruvates
-Pyruvate is a 3 carbon sugar
-Glycolysis happens in the cytoplasm
-Glycolysis makes 4 ATP but two of them are used in the process so only two ATP are saved
After Glycolysis
-After glycolysis there are two options for the pyruvate
-If there is oxygen present the pyruvate goes through aerobic (with air) respiration
-Aerobic respiration takes place in the mitochondria also known as cellular respiration
-If there is no oxygen present then the pyruvate cannot enter the mitochondria and instead goes through anaerobic respiration
-Anaerobic (without oxygen) respiration takes place in the cytoplasm.
-There are two types of anaerobic respiration also known as fermentation
-Alcohol fermentation
-Lactic Acid fermentation (animals)
The basics of glucose breakdown
Activity:
Storyboard or Comic of Cellular Respiration
There are many steps involved in glycolysis and the Krebs cycle. You are to create a storyboard or a comic involving each step.
Listed below in bullet form are all of the major steps of both glycolysis and the Krebs cycle. I want you to create a flash card or single cell comic for each step. For example the first step in glucose activation is the addition of 2 phosphates to the glucose molecule. These two phosphates come from ATP. This step is known as phosphorylation and the Glucose molecule containing the 2 new phosphates is called Fructose Bisphosphate. This step should be explained and accompanied by an illustration of it happening.
Glycolysis
-Two parts
-Glucose activation
-Energy Harvesting
Glucose Activation
-Two phosphates are added to the glucose molecule (Phosphorylation)
-The two phosphates come from 2 ATP's
-The phosphorylated glucose molecule is called fructose bisphosphate
-Because fructose bisphosphate is unstable it breaks apart into two G3P's
-G3P stands for glyceraldehyde-3-phosphate
-The 3 is because of the number of carbons it has
Energy Harvesting
-The 2 G3P's lose their high energy phosphates releasing two ATP's each
-Because their is 4 ATP's made and 2 ATP's used during the activation process we say there is a net gain of 2 ATP
-The two G3P's that lost their phosphates are now called pyruvate
-The goal of glycolysis is to make the two pyruvates so they can enter the mitochondria
Aerobic and Anaerobic Exercise
-In order to enter the mitochondria and begin cellular respiration there must be oxygen present
-If there is oxygen present the process is known as aerobic respiration
-If there is no oxygen present then the pyruvate cannot enter the mitochondria
The Krebs Cycle
-The Krebs cycle is also called the citric acid cycle
-Because citrate (the ionized form of citric acid) is the first molecule produced in the cycle
-First stage of aerobic respiration
-Pyruvate is split to form CO2 and an acetyl group
-The acetyl group attaches to CoA (Co-Enzyme A) to make acetyl CoA
-Acetyl CoA enters the Mitochondria along with the NADH that was produced from glycolysis
-Second Stage: The Krebs Cycle
-Acetyl CoA donates its acetyl group to the four carbon molecule oxaloacetate, forming citrate
-CoA is now released and done
-H2O donates a Hydrogen to the CoA molecule and oxygen to the citrate
-Citrate is rearranged to form isocitrate
-Isocitrate forms Alpha-ketoglutarate by releasing CO2
-Two electrons and a H+ are captured by NAD+ to make NADH
-Alpha-Ketoglutarate forms succinate by releasing CO2
-Two new energetic electrons and a H+ are captured by another NAD+ to make another NADH
-And additional energy is captured in an ATP
-At this point all three carbons from the pyruvate have been released as CO2
-Succinate is converted to malate, which contains two additional hydrogens and one additional oxygen from H2O
-Malate is converted to oxaloacetate
-Two more energetic electrons and a H+ are captured by NAD+ to make another NADH
-At the end of all that a total of 10 NADH and 2 FADH2 have been created
-This is the main source of ATP
-The NADH and FADH2 are going to transport H+ through the mitochondrial matrix so they can create a H+ concentration gradient.
-Through the process of chemiosmosis the H+ are going to push through the ATP synthase generating the majority of ATP
Redox Reactions
Redox = Reduction and Oxidation
-Reduction is when an electron is added (the electron is negative that is why it is a reduction)
-Oxidation is the loss of an electron
-An electron donor is called a reducing agent
-An electron acceptor is an oxidizing agent
During cellular respiration
C6H12O6 (Glucose) becomes oxidized into 6 CO2
6 O2 gets reduced to 6 H2O
One of the main goals of cellular respiration is to get electrons to the electron transport chain
It is the electron transport chain that makes most of the ATP
-In order to get the electrons to the electron transport chain NAD+ and FAD+ need to carry electrons there
-Most of cellular respiration tries to turn NAD+ into NADH and FAD+ into FAD2
Glycolysis breaks glucose down via substrate-level phosphoralation (adds phosphates from ATP to break up the glucose)
The electron transport chain uses a process called oxidative phosphoralation
-The electron transport chain goes through a process of losing electrons through the process of phosphoralation
-The lost electrons then go through chemiosmosis which generates most of the ATP by powering the ATP synthase
Cells can get energy out of most macromolecues
Watch this video on an AP Bio cellular respiration lab
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