Summary

This document provides an overview of biological processes related to carbohydrate, lipid, and protein metabolism and the functions of these organic compounds.

Full Transcript

Class test 2: Lecture 7-12, Labs 3-6 Lecture 7: Read pages 944 - 952 **Carbohydrate process:** - - Carbohydrates are ingested primarily in the form of disaccharides, starch and glycogen. a. b. **CARBOHYDRATE PROCESSES:** A. B. **Polymerizes glucose to form glycogen [DONE IN LIVER...

Class test 2: Lecture 7-12, Labs 3-6 Lecture 7: Read pages 944 - 952 **Carbohydrate process:** - - Carbohydrates are ingested primarily in the form of disaccharides, starch and glycogen. a. b. **CARBOHYDRATE PROCESSES:** A. B. **Polymerizes glucose to form glycogen [DONE IN LIVER & SKELETAL MUSCLE]** **Glycogenesis**: occurs when glucose supplies exceed demand for ATP (when more glucose is available than can be used , the rise in ATP causes glucose to be stored as glycogen or Fat. -- the body can store much for fat than glucose (80-85% of stored energy) \*The glucose that is taken up by hepatocytes in the liver and by skeletal muscle is COVALENTLY BONDED TOGETHER to form glycogen stores\* - - - \*\*High ATP levels turn **off** glycolysis - when glucose form long chains to make glycogen that is called **glycogenesis.** **Formula: GLUCOSE - GLUCOSE 6 PHOSPHATE - GLUCOSE 1 PHOSPHATE - GLYCOGEN** C. **Hydrolyzes(breaks down) glycogen (polymer) to glucose monomers [DONE IN LIVER & SKELETAL MUSCLE]** **Glycogenolysis**: stimulated by low blood glucose **Formula: (GLYCOGEN SPLITS = GLUCOSE 1 PHOSPHATE - GLUCOSE 6 PHOPHATE - GLUCOSE (USED FOR ENERGY) - once glucose reaches muscle cells, the glucose 6 phosphate is stuck, hepatocytes act as an enzyme since they have glucose 6 phosphate and allow the glucose to diffuce from the cell into blood.** D. **Forms glucose from noncarbohydrate precursors. \*\*[ONLY DONE IN THE LIVER]\*\*** **3- Gluconeogenesis: forming new (neo) glucose from NON CARBOHYDRATE MOLECULES** **How? When too little glucose is available for the metabolism, glucose is made from AMINO ACIDS and GLYCEROL.** **When? When dietary sources (food) and glucose reserve are used up and the pt's glucose levels are beginning to drop.** **\*\* gluconeogenesis protects the nervous system from the adverse effects of hypoglycemia by making sure ATP synthesis keeps going.** ***\*\*\*\*GLUCOSE is taken up as needed by brain cells. UPTAKE by other body cells is regulated by INSULIN. \*\*\**** ***---\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--*** **Lipid process:** - 1. 2. - 1. 1. 2. 3. **Triglyceride absorption:** - - - - - - - - - - **The total number of adipocytes generally remain constant except in children before puberty** **Lipemia: the presence of too many chylomicrons in blood plasma \*\*has milky appearance\*\* after a fatty meal.** **Muscle cells and adipocytes actively remove triglycerides from the chylomicrons in the bloodstream for 4-6 hours** **Adipose tissue is stored :** **1- subcutaneous** **2- kidneys and heart** **3- within the abdomen (visceral)** **4- breast, hips and buttocks** **VLDP (very low density Lipoproteins): when Chylomicron remnants enter the liver, they are combined with more proteins and any synthesized triglycerides from lipogenesis to form VLDP. Which are released back into the blood.** - **As triglycerides are released, the density of lipoproteins increase so VLDL transform into LDL** **LDL's - contain mostly cholesterol and are taken up by cells through receptor mediated endocytosis.** - **The liver also produces and releases HDL : HDL'spick up excess cholesterol and phospholipids from the tissues to the liver.** **Bad cholesterol:** - - - **Good cholesterol:** - - **PROTEIN** **Protein Process:** - 1. 2. - 1. **Deanimation:** - - - - **Keto acids:** - - - **Amino Acids are used to create new proteins, the remaining or excess amino acids from our diet are used to fuel cellular respiration. BUT they have to be modified in the [liver] first.** **Proteins provide structural integrity of muscles/tendons/ligaments.** **Other proteins functions as:** **1- enzymes** **2- hormones** **3- neurotransmitters** **4- cell receptors** **5- antibodies and cell membrane transport proteins** **METABOLIC BALANCE** The rate of catabolism = the rate of anabolism During embryonic and fetal development, infancy and childhood (growth and development) The rate of anabolism must exceed catabolism- there is more building up of tissues than the breakdown of tissues. Once you're an adult, if you eat more food (anabolism exceeds catabolism)= weight gain. **Catabolic processes:** fuel cellular respiration **Anabolic processes:** synthesize cell products and store energy for times in need. It depends on the needs of the body to determine if we need an anabolic or catabolic reaction. The body has nutrient pools: the current stock of available amino acids, carbs and lipids in the body. **The body aims to maintain the nutrient pools regardless of whether we've eastern or not.** **Organs involved in managing nutrient pools:** **1- liver (stores glycogen and performs key metabolic reactions)** **2- Adipose tissue (stores triglycerides)** **3- Skeletal muscle (stores glycogen & abundant in protein)** **Metabolic states: there are only 2:** **1- Absorptive (fed state): the time during and shortly after eating - NURTRIENTS ENTER THE BLOOD STREAM FROM THE GI TRACT.** a. b. c. **2- Post-Absoptive (Fasted state): the time when the GI TRACT is empty and the energy source are supplied by the break down of body reserves.** **\*\* just like with nutrient pools, our bodies must maintain an adequate supply of nutrients to cells for ANABOLIC processes and energy at all times [regardless] if we are in a FED or FASTED state.** **LECTURE 8: POST-ABSORPTIVE (FASTED) STATE** **Reading: Pages - 952-954** **-** **Post- absorptive state goals:** - - - **Post-absorptive mechanisms can sustain the body for extended periods of time even weeks, as long as adequate levels of water are taken in.** **What happens at the end of the absorptive state:** - - - - **Carbs:** - - **Lipids:** - **Proteins:** - **Post-Absorptive State Processes: IT IS CATABOLIC!** - - - - - **1- Glycogenolysis:** a. b. c. d. e. f. **\*\*glycogenolysis in muscle :** **Glycogen in muscle is broken down into glycogen-6-phosphate and is primarily used to fuel cellular respiration IN THE MUSCLE. If needed pyruvate (O2 present) or lactic acid (O2 absent) can be released into the blood AND then picked up by the liver to be converted into glucose then released back into the blood.** **2- Lipolysis/mobilization/ B-Oxidation:** a. b. c. d. e. f. **B-Oxidation: Fatty acids are taken up into mitochondria and broken down into 2 carbon subunits.** - - **Lipid metabolism in the LIVER:** **\*\*Side note\*\* during the postabsorptive state, your LIVER picks up two things:** **1- free fatty acids** **2- glycerol from bood** - - a. b. **Remember, the goal of the liver during the post-absorptive state is to maintain normal blood glucose levels. So becasue the liver cannot use the AcetlyCoA made from beta-oxidation NOR can it use the ACA from the citric acid cycle it does this:** - **3- Gluconeogenesis** **Glucose is made from non carbohydrate precursors (sources)** - 1. 2. **This proecss occurs in the liver, but the kidneys also do it.** **The glucose being made is used to keep the brain functioning normally. The rest of the body's cells can rely on fats & proteins for energy. - this is called GLUCOSE SPARRING** **4-Proteolysis** **Amino acids are used to make glucose and fuel cellular respiration** - - - - **5- Ketogenesis** - - - - - **There are 3 types of ketone bodies that come from ACA:** 1. 2. 3. - - - **ACETONE:** - - - - - **KETOSIS:** **During a fed state: - low concentration of ketone bodies in blood and few compounds appear in urine** **During a fasted state or Keto-Diet:** - **Ketonemia: high concentration of ketone bodies in blood** **Ketonuria: high concentration of ketone bodies in urine** **What do those 2 conditions indicate? That catabolism of proteins and lipids are under way.** **KETONE BODIES:** - - - **Even during prolonged fasting, ketone body levels do not accumulate that much to cause such problems because:** 1. 2. 3. **KETOACIDOSIS:** - - - - - **Nervous tissue:** - - **Lecture 9: Concept 16.11 on the pancreas & diabetes, and concept 24.7** **Homeostasis and Disorders of metabolism** **What are the 2 goals of metabolism:** **1- Maintain fuel supply for cellular respiration to all cells regardless of metabolic state** **2- Maintain blood glucose concentration within normal range \*\*especially important\*\*** **How does it do this?:** - - **The endocrine cells make up how much of the organ's total mass?** - **What is most of the pancreas is used for?** - **Where are endocrine cells housed?** - **Alpha (a) cells secrete what? Glucagon** **Beta (b) cells secrete what? Insulin \*\* most abundant of the islet cells\*\*\*** **Pancreatic islets are closely associate with what?** - **Hormones are released in bulk by?** - **What determines which hormone is released?** - - **\*\* Incretin:** - - - **What allows the nervous system to influence metabolism?** - **Insulin and glucagon with antagonistically to maintain plasma glucose concentrations** - - **[Absortive state:]** - - - - - - **When insulin binds to receptors on target cells it:** **STOPS: (Metabolic pathways of the post-absorptive state):** - a. b. c. d. e. **STARTS: (Metabolic pathways of the absorptive state):** - a. b. c. d. e. **Insulin's mechanism of Action:** - **Target cells are:** 1. 2. 3. **Insulin makes it easier for glucose to enter the target cells by [stimulating the insertion of a glucose transport protein (door), its called GLUT-4 into their membrane:] \*\*simplified\*\* -** **"*Inserting a transport door made of protein called GLUT-4 in the membrane so glucose can pass through"*** **Then once in the blood, insulin binds to its receptors ON target cells and stimulates:** 1. 2. 3. **of glucose by activating the pathways of the absorptive state \*\* see anabolic processes\*\*** **\*\*\*GLUT-4 transporters:** - - - - **Insulin secretion: Stimulate, Amplify or Inhibit:** 1. - - - **\*\* parasympathetic stimulation of GI tract and pancrease Increases during and following a meal. The parasympathetic input to *beta* cells also stimulates insulin secretion\*\*\*** 2. - 3. - **\*\* during times of stress or physical exertion, insulin secretion is inhibited.** **Which hormones reinforce this by being release from the adrenal medulla? \*\* hint\*\* ADRENAL:** - **Why?** - **[Post-absorptive state:]** - - - a. b. c. d. **Factors that influence the stimulus for Glucagon secretion:** 1. 2. 3. **Abnormally elevated plasma glucose concentration is also called?** - **What causes it?** - **TYPE 1 DIABETES:** **Type 1 Diabetes:** - - - - a. b. - - - - **Symptoms:** a. **\*\* Certain neurons in the hypothamalamus which govern hunger are insulin dependent - since there's no insulin, it increases feelins of hunger\*\*\*** b. c. d. e. f. g. h. i. - - - j. **Treatments:** - - **TYPE 2 DIABETES** **Type 2 diabetes:** - - - a. b. c. - - - **Complications:** - - - - - - **Treatment:** - - - - - - - a. b. c. d. **Lecture 10: Protein and nucleic acids** **Read concepts : 2.10- 2.12** **Protein review:** - - - - **A complete protein: 1 or more polypeptide chain that is folded, coiled or twisted into a specific shape: [conformation ]** **Proteins make up 50% of the mass of a cell** **Their main functions: enzymatic protein (selective acceleration of chemical reactions), storage protein (storage of amino acids), defensive proteins (protection against disease), and transport proteins (transport of substances)** **Other Protein functions:** 1. **Ex:// insulin- a hormone secreted by the pancreas causes other tissues to take up glucose which regulates blood sugar concentration.** 2. **Ex: Receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells. (Ex. Post synaptic cleft)** 3. **Ex:// motor proteins are responsible for the undulations of cilia and flagella. Actin and myosin are responsible for muscle contractions.** 4. **Ex:// keratin being the protein of hair and other skin appendages, collage and eslatin proteins provide fibrous framework in animal connective tissues** **Amino Acids:** **Contain:** 1. 2. 3. 4. **Remainder group : R-group** **Buffering capacities:** - - **R-Groups:** - - **What are the 3 types of R groups:** 1. 2. 3. **Non-polar R-goups: G, A, V, L, M, P, W** - - - **Polar R-Goups: S, T, C, Y, N, Q** - - - **Electrically charged R-goups:** - - - **Amino acids with a carboxyl (c ) in the R-goup are acidic - releases H+ ( D or E)** **Amino acids with nitrogen (N ) in the R-group are basic - accept H+ (K, R or H)** **Hydrophobic:** - - ![http://upload.wikimedia.org/wikipedia/commons/5/50/Cartoon\_of\_protein\_hydrophobic\_interaction.jpg](media/image6.jpg) ![](media/image5.jpg) **Amino acids with a carboxyl (C ) in the R-group are acidic - Releasing H+** **Amino acids with nitrogen (N ) in their R-group are basic, accepting H+** **Polypeptides:** - - **There are 4 structural levels of proteins:** 1. 2. 3. 4. **Primary: (looks like a snake)** - - - - **Secondary: Looks like a helix** - - - - **Tertiary structure: (3D shape - looks like a ghost)** - - - a. b. c. **\*\* so the three types of R-goups plus disulfide bonds\*\*\*** d. ![](media/image1.jpg) - a. b. **Quaternary structure:** - - **Protein denaturation:** - - - **By heat:** - - **By alcohol:** - - - **Nucleic Acid:** - - **Nucleotides (monomers):** - - **Nigrogenous base: they make up the genetic code** - - - - - **1 Sugar: make up the structural backbone of the strand** - - **1 phosphate group: make up the structural backbone of the strand** **The genetic code is always read in the 5' to 3' direction** **Differences between DNA & RNA:** - - - - - - - - - **Lecure 11: protein synthesis** **Concept 3.11 - Focus figure 3.4** **How do the instructions for making a protein (DNA) get converted into a protein?** - **There are two steps:** 1. 2.

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