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15 Cards in this Set

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Define metabolism, anabolism, catabolism.
Metabolism - All of the chemical reactions that take place within the body. The most active sites are the liver and muscle cells.
Catabolism - refers to breakdown reactions that yeild energy; the goal is to produce ATP
Anabolism - refers to reactions that build compounds, aka biosynthesis. These reactions generally require ATP.
Why is ATP a high-energy compound? How is it used for cellular energy?
Because of its structure, ATP has very high energy bonds between its phosphate groups. When the bonds are broken, energy is released for cellular functions and biological activities.
Describe the main steps in the catabolism of glucose to yield energy. Identify the appropriate pathways, the inputs to each pathway, the outputs from each pathway, and whether the pathway is aerobic or anaerobic.
1. Glycosis (Anaerobic): Inputs-Glucose and ATP. Outputs: 2 pyruvate, 2 NADH + H, and a net gain of 2 ATP. It occurs in cytosol and some steps are irreversible.
2. Pyruvate to Acetyl CoA (Aerobic): Inputs-Pyruvate and Coenzyme A; Outputs: 2 Acetyl CoA, 2 NADH + H, 2 CO2
3. Citric Acid Cycle, Krebs Cycle, Tricarboxylic acid cycle (Aerobic): Inputs: 2 Acetyl CoA and Oxaloacetate acid; Outputs (two turns for two acetyl CoAs): 2 GTP, 6 NADH, 2 FADH2, 4 CO2 (note: there is no net gain or loss of CO2).; This cycle can also use the intermediates for biosynthesis of amino acids and fatty acids.
4. Electron Transport Chain (Aerobic): Inputs: NADH + H and FADH2; Outputs: The H becomes H2O and the electrons are shuttled to oxygen to drive synthesis of ATP and H2O. SO IN THE END, ONE MOLECULE OF GLUCOSE PRODUCES 30 TO 32 ATP. THE END PRODUCTS ARE: CO2, H2O, AND ATP.
Describe the main steps in the catabolism of triglycerides to yield energy. Identify the appropriate pathways, the inputs to each pathwy, the outputs from each pathway, and whether the pathway is aerobic or anaerobic.
First, fatty acids are broken down into glycerol and FAs. The glycerol (3C) is then converted to pyruvate or glucose in the liver, where it then continues down the other 3 pathways to yield ATP, CO2, and H2O.
1. Fatty acids must be activated. This happens by combining w/ Coenzyme A. It requires input of ATP.
2. Carnitine carries the fatty acids from the cytosol to the interior of the mitocondrion. This starts BETA-OXIDATION.
3. BETA-OXIDATION (Anaerobic): Inputs: ATP. Outputs: 2 Carbons are clipped off and produced to Acetyl CoA. Each one produces 1 FADH2 and 1 NADH. The last 2 carbons don't do this.
4. KREBS CYCLE: Inputs: Acetyl CoA. Outputs: ATP/GTP, NADH, FADH2, CO2
5. ET CHAIN: Inputs: NADH and FADH2. Outputs: H2O and ATP
Describe the main steps in the catabolism of animo acids to yield energy. Identify the appropriate pathways, the inputs to each pathway, the outputs from each pathway, and whether the pathway is aerobic or anaerobic.
1. DEAMINATION (Anaerobic): NH2 is removed, quickly converted to NH3, then to urea in liver until it is excreted in urine via the kidneys. Too much protein can cause problems. Inputs: Amino Acid or NH2. Outputs: Urea
2. THE CARBON SKELETON (Anaerobic): With NH2, all we have left is C, H, and O atoms. Depending on the number of C's, the carbon skelton can enter any of the pathways: Pyruvate to Acetyl CoA, Krebs Cycle, or ET Chain. 3C to pyruvate. 2C to Acetyl CoA. And 4C, 5C, 6C to citric acid cycle. From there, the process continues to produce H2O, Co2, and ATP. Only the carbon skeleton, not the amino acid, produced ATP.
What are the end products of the complete catabolism of glucose, triglycerides, and AA?
They produce all H2O, CO2, and ATP. An extra rule for proteins is that they also produce urea and that the ATP is provided by the carbon skeleton, not the amino acid. Also, a tricky question is that triglycerides lead to glycerol and fatty acids. The glycerol then produces ATP whereas the fatty acid produces CO2, H2O, and ATP.
How does the body dispose of excess N?
It converts it NH3, then urea, and then it is secreted in the urine. Liver problems will impair NH3 to urea function, making NH3 toxic. Kidney problems will store urea in body causing damage. The excess carbon skeleton is used to make energy, glucose, or fat.
Describe the main steps in the biosynthesis of glucose and glycogen.
GLUCONEOGENESIS: Through a process called gluconeogenesis, the body makes glucose. Pyruvate, lactate, glcogenic amino aCids (not all amino acids are make glucose), and glycerol all can make glucose. Fatty acids are the only ones that cannot. The process of gloconeogenesis is the reversal of glycolysis, but what makes it different is that it uses energy-consuming detours. Through the Cori cycle, pyruvate is inhibited from converting to acetyl CoA because of low O. So w/ help of oxaloacetate, pyruvate and glucogenic AA are made to glucose. Glycerol is already close to being glucose. With Cori cycle, lactate becomes pyruvate and then glucose. This occurs 90% in liver and 10% in kidney. All these compunds are converted to pyruvate and then to glucose. The process requires ATP and NADH.
As for glycogen, through a process called GLYCOGENESIS, glucose assembles into glycogen. When it needs to break it down, the procress is caled GLYCOGENOLYSIS. Liver glycogen is reserve for the blood. Muscle glycogen is glucose for muscle. In muscle, breakdown is glycolysis. In the liver, glycogenolysis produces glucose that then moves into the blood stream.
Describe the main steps in the biosynthesis of triglycerides.
Inputs: Fatty acids, ketogenic AA (can become ketone bodies or fat), and any compund that can be metabolized to form acetyl CoA can make fatty acids. The process is known as lipogenesis.
LIPOGENESIS: With supply of ATP that is brought by NADPH, the body produces fatty acids. While it is the reversal of beta-oxidation, it is not because these pathways use different reactions and take place in different locations(cytosol instead of mitochondria). It also requires energy, instead of releasing it. The fatty acids are then joined to glycerol to make triglycerides and then stored. Proteins and fats can lead to fat storage. As for carbs, they provide little fat, but shift the body's fuel prefernces towards burning calories and less fat.
Describe the main steps in the biosynthesis of protein.
Your bodies builds proteins from amino acid pool. That pool comes from, or the inputs are: amino acids, breakdown of body proteins, and some produced in cell. The body then makes the NEAA and combines them with EAA to synthesize protein. To make the NEAA, the body has difffrnt pathways. These amino acids are built from carbon skeletons, that come from pyruvate, compunds formed through glycolysis, citric acid cycle, and other amino acids. Then through the process of transamination, we take one amino group from one AA and add it to a carbon skeleton to form new AA.
What non-carbohydrate substances can be used to make glucose?
Amino Acids and Glycerol. NOT FATTY ACIDS.
What adaptations does the body make during a fast?
First, it preserve glucose-dependent tissue. its second priority is to mainmtain muscle mass. So the body obtains fuel from stored glycogen, then stored fat, and then proteins. Over time, the body adapts to using ketone bodies for fuel instead of glucose because that is more important for glucose-dependent tissues.
What are ketone bodies made from? Define ketosis.
When no carbohydrate is available to complete break down fat for energy, ketone bodies are produced for energy. When ketones build up, you have ketosis. This devlops in starcation, diabetis, and chronic alcoholism. It causes dehydration, interferes with acid-base balance, causing blood to become acidic. In ketogenesis, some acetyl becomes ketone bodies because there is an excess amt. of acetyl CoAs. If not secretred or converted back to acetyl CoAs, ketosis develops.
How are body weight and energy stores affected by feasting or fasting?
In feasting, we increase the stores (anabolism). With fasting, the stores are broken down (catabolism). Eventually when all the fat stores are gone, we use protein and produce ketosis and rely of ketone bodies as additional energy source.
What does it mean that fat burns in a flame of carbohydrate?
It means that Acetyl CoA from beta-oxidation can enter Krebs cycle only if its synchonized with fat and carb breakdown. Fat depends on carbs to privide oxaloacetate and thereby giving it entry. If there is no oxoalacetate, then the acetyl CoA forms ketone bodies.