Intro to Metabolism - Video Tutorials & Practice Problems
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Intro to Metabolism Concept 1
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Hey, everyone. So in this video, we're gonna talk about metabolism. Now when we say metabolism, well, that refers to all biochemical reactions that take place within an organism. And when we're referring to metabolism, we're referring to metabolism versus annibal with metabolism, we're gonna say we have reactions that produce energy by breaking down molecules into smaller ones. And the opposite of catabolism is anabolism with anabolism. We say that these are reactions that use energy to build larger molecules from smaller ones. If we take a look here at this image, we're gonna say we have our larger molecules here and if we're going uh this way, we're breaking them down into smaller molecules, remember smaller molecules means that we're going to do catabolism. And as we break it down, we're releasing energy over here. If we look at the opposite way, we're taking some energy, we're investing it into our smaller molecules in order to build up to larger molecules going this way is anabolism. So just remember cannibalism, we breaking down to produce energy anabolism, we're building up, but it requires energy to do. So
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Intro to Metabolism Examples 1
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In this example, question, we need to identify each of the following processes as anabolism with a or catabolism with ac. For the first one, we're gonna say trypsin in small intestine converts proteins into smaller peptides. So they're telling us we have larger protein than they're getting broken down into something smaller. Remember, we're breaking molecules down into smaller molecules that is metabolism. So this would be c next glucose is converted to glycogen for storage. Remember our chapter, if you watched our videos, these are carbohydrates. We're gonna say here glucose is just a monosaccharide. Glycogen is a polysaccharide. It's a bunch of glucose molecules strung together. So we're going from a smaller molecule in the form of glucose to a larger molecule in the form of glycogen. So we're building up to something bigger. So this is anabolism. Next lipase in the stomach hydrolyzes lipids to fatty acids and Glycerol hydrolyzes or hydrolyzes means we're using water to break bonds. We're breaking things down into smaller pieces. So this would be metabolism and then amino acids in ribosomes are converted into proteins. So here, remember amino acids, we connect them to each other through bonds. We go from our primary structure all the way to our quant structure to make our proteins. Here, we're going from a smaller molecule to a much larger molecule. So this is anabolism. So this is how we identify each one of these statements, whether it's anabolism with an A or catabolism with AC.
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Metabolic Pathways Concept 2
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Now, we know that metabolism consists of anabolism and metabolism. Well, both of them take place through metabolic pathways. And we're gonna say recall a metabolic pathway is a sequence of interconnected biochemical reactions taking place in an organism. These metabolic pathways can be either linear. So if we take a look here, we're starting out with our molecule. A, it undergoes some type of reaction with an enzyme. One to create B and then it continues with another enzyme to create C and then C lastly goes to D with the help of a third enzyme, but they can also be cyclic. So in this one, we have a here but then it goes cyclic like this. Within this chapter, we're gonna take a look at both linear as well as cyclic pathways in relation to metabolism.
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Metabolic Pathways Example 2
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Which of the following statements about metabolic pathways is correct. So for A I says the product of the last reaction in a cyclic metabolic pathway is a reactant in the first reaction. This is true. Remember when we looked at the cyclic pathway, we ended with our product D but product D can feed back into our first reactant A and the cycle begins all over again. So basically, the product of a reaction can help to become uh the substrate or reactant of the next reaction. So here a is true, catabolism always takes place through cyclic pathways. That is not true. Catabolism could go through linear or cyclic pathways. We talked about both possibilities. When it comes to metabolism, linear catic pathways produce energy. While cyclic catic pathways use energy, we never said this. All we said is that there's two types of pathways, there are linear as well as cyclic. We never talked about either them uh creating energy or using energy. And then here the last reaction in some linear pathways can produce a star material for the rea for the first reaction. No, in a linear reaction, think of it as a chain of reactions connected together to connect it together. And it's an assembly line at the end of the assembly line. That's it. That's our last product. That product doesn't loop back around to make our beginning reacted. So here option A would be the only correct statement.
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Stages of Catabolism Concept 3
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Now, when it comes to the stages of catabolism, we're gonna say that energy production through metabolism of food takes place in four stages. So we have stages 1 to 4. Here. Now, here we're going to say connected to this idea is aerobic respiration. We're gonna say the predominant energy production pathway in the body takes place in the presence of oxygen gas or 02 gas. Now, if we take a look here, we have stage one and we're starting out with our proteins, carbohydrates and lipids. We're gonna say that these are present outside of the cell. So here these are outside. Stage one deals with digestion. So we're consuming these things and digestion is gonna help us break them down. The proteins are broken down into their amino acids, carbohydrates to the monosaccharide and are lipids into their fatty acids. Once we pass this barrier, which means that we're going into the cells, we have aerobic respiration taking place. And in stage two, we're gonna say we have acetyl coa formation. So here we have acetyl coa and represented by this structure. And we're gonna say that in stage three, it can go into the citric AIC cycle. We're gonna have the production of our electron carrying structures in the form of N A DH N FA DH two. We also have the creation of A TP or energy and carbon dioxide. Finally, from stage three to stage four, we have our electron transport chain and oxidative phosphorylation which leads to even more production of energy in the form of A TP. Now, here we're going to say that stages three and four are called our common metabolic pathway. And we're gonna say that means that stages three and four are identical for the metabolism of all food types because at this point, it's broken down to such a fundamental level that we everything is going to be the same in terms of stages, three and four. Stages, one and two are not the same throughout because different enzymes are required to break down proteins, carbohydrates and lipids into their respective amino acids, monosaccharide and fatty acids. We can also say that for stage two, we're gonna have different pathways that are needed for amino acids, monosaccharide and fatty acids. So there's a lot of differences in stages one and two, but stages three and four is where we have our common metabolic pathway, right? So this just gives us a great overview, broad overview for the stages of food metabolism or breaking down foods that we consume
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Stages of Catabolism Example 3
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Which of the following statements about the metabolism of food is incorrect. A carbohydrates are oxidized in stage one to produce carbon dioxide and energy. This statement is incorrect because remember in stage one, we have the digestion of carbohydrates to create our respective monosaccharide. So this is incorrect. So this is our answer. Next one for being acetyl coa is the product of stage two metabolism. That is true. We make acetylate which then goes into the citric acid cycle to produce energy as well as carbon dioxide. The electron transport chain in oxidative phosphorylation is the last stage of food metabolism. That is true that eventually leads to the production of more A TP energy. The citric acid cycle uses acetyl coa to produce energy. Yes. The uh the acetylate that goes into the citric acid cycle does produce energy as well as CO2. This statement is true. So out of all our options, only option A is incorrect.
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Problem
Problem
Which one of the following catabolism stages produces NADH?