Textbook Notes (368,432)
United States (206,039)
Nutrition (22)
NTR 306 (22)
Chapter 7

NTR 306 Chapter 7 Metabolism Notes.docx

6 Pages
Unlock Document

NTR 306
Deanna Staskel

Chapter 7: Metabolism Energy from Food:  During digestion, o Energy-yielding nutrients are broken down to [feasting]  Monosaccharides  Fatty acids  Glycerol  Amino acids o Fasting – the body breaks down stored macronutrients from stored glycogen (glucose); body fat (triglycerides); amino acids  During metabolism o They are converted into a usable form of energy for cells [ATP], water a2d CO o BODY ALWAYS NEEDS ENERGY SO METABOLISM NEVER STOPS Cellular Energy & ATP: Cells are unable to use macronutrients directly for energy! ATP (adenosine triphosphate):  Only source of energy that can be used directly by cells  High energy molecule o Composed of adenine, ribose and 3 phosphate molecules o  Must continually ‘recharge’ ATP to provide a constant supply of energy  When cells need energy, a phosphate group is broken off of ATP o Releases energy & inorganic phosphate (ADP) Anabolic and Catabolic Reactions: Anabolic reactions – use ATP to combine smaller molecules (like glucose) into larger compounds (like glycogen) and release small amounts of heat  During times of plenty, favored by metabolism  Excess carbohydrates are o stored as glycogen in the liver and muscle o stored as fat in the adipose tissue  Protein is used for building body proteins o Excess converted to fat and stored  Excess dietary fat is stored in adipose tissue  Glucose + glucose  glycogen  Glycerol + fatty acids  triglycerides  Amino acids + amino acids  protein Catabolic reactions – break down larger molecules into smaller compounds and release ATP and heat  Liver glycogen providing blood glucose  Muscle glycogen is used for fuel by the muscles  Adipose tissue released fatty acids to be transformed into ketone bodies in the liver and used by the brain as fuel  Body proteins are converted to glucose  Glycogen  glucose  Triglycerides  glycerol + fatty acids  Protein  amino acids Chapter 7: Metabolism METABOLISM TAKES PLACE WITHIN CELLS:  Cytosol/cytoplasm o Fluid portion of the cell o Site of anaerobic metabolism in the cell  Mitochondria o “the powerhouse of the cell” o The site of all aerobic metabolism o Contained in all cells  Except RBCs when they mature o Some have more than others, making some more metabolically active than others  Liver and heart cells have a lot Carbohydrates to Energy:  Glucose is the most important macronutrient for ATP production! o Important for brain and RBCs o Unique b/c it can produce ATP anaerobically & aerobically  Derived from ingestion, digestion and absorption of carb-rich foods o Or broken down from glycogen stores  Glycogenolysis o Or converted to glucose from amino acids, glycerol, lactate  Gluconeogenesis Glycolysis:  Breakdown of glucose  First step in forming ATP from glucose  Takes place in the cytosol of the cell  10-step catabolic process  1 six-molecule glucose process to two 3C molecules of pyruvate o Net of 2 molecules of ATP o 2 H are transposed to ETC Pyruvate:  An intermediate product formed during the metabolism of carbohydrates  Creation occurs in the cytoplasm of the cell  No oxygen is required to form it  Small amount of energy is formed o 2 ATPs + 2 NADH + H per glucose  Without adequate oxygen, pyruvate remains in the cytoplasm and is converted to lactate (lactic acid) o It is released into the blood and taken to the liver o Lactate is then converted to glucose  Can then undergo glycolysis to pyruvate again  Called the Cori Cycle Pyruvate to Lactate:  Pyruvate reduces to lactate to prevent H ions from building up in the cell +  During intense exercise+ lactate is not produced fast enough to keep up with H production o The buildup of H ions reduces pH in the muscle cell  Leads to the “burning” sensation in muscles after exercise Chapter 7: Metabolism Pyruvate to Acetyl-CoA:  After emerging from glycolysis, the 2 pyruvate are transported into the mitochondria o Pyruvate  acetyl-coenzyme A (acetyl-CoA)  The starting product in the TCA cycle  2 pyruvate + 2 coenzyme A + 2 NAD  2 acetyl-CoA + 2CO +22 NADH Anaerobic Metabolism:  Produces more ATP per minute  Limited in use o Provides only 1-1.5 minutes of maximal activity  Involved in high-intensity, short-duration activities o Ex: sprinting, heavy weight lifting Aerobic Metabolism:  Produces less ATP per minute  Is able to produce ATP indefinitely  Involved in low-intensity, long duration activties Enzymes, Cofactors & Coenzymes: Enzymes – protein catalysts that cause chemical reactions  Remains unchanged after the reaction Cofactors – inorganic components of an enzyme needed for the enzyme’s activity  Often a mineral  Must be attached to the enzyme’s active site Coenzymes – organic molecules that function as enzyme helpers  Accepts and donates H , electrons and other molecules during reactions +  NAD (nicotinamide adenine dinucleotide) o Derived from B vitamin [niacin (B3)] o Reduced to NADH +  It accepts 1 H atoms  FAD (flavin adenine dinucleotide) o Derived from B vitamin [riboflavin (B2)] o Reduced to FADH 2 +  It accepts 2 H atoms Triglycerides: Glycerol and fatty acids can be derived from diet OR lipolysis [enzymatic breakdown of triglycerides (from adipose tissue) into glycerol and fatty acids by hormone-sensitive lipase]!  Glycerol o Gluconeogenesis – converts glycerol to glucose in the liver  Fatty acids o Ketogenic – normally converted to acetyl CoA (fatty acid oxidation)  Acetyl-CoA can form ketones if glucose supply is inadequate o Fatty acid oxidation  Series of chemical reactions that break down fatty acids to molecules of acetyl-CoA  Fatty acid is taken apart 2C at a time  Hydrogen and electrons are released to ETC  Each 2C pairs are joined by other CoA and converted to acetyl-CoA  The acetyl-CoA then enters the TCA Cycle to produce energy Amino Acids:  Major role is as building blocks from proteins and other-containing compounds  If the AA is not used to build protein, the amine group must be removed through deamination o Ammonia, toxic to cells, is converted to urea o Deamination leaves an alpha-keto acid Chapter 7: Metabolism  Occurs mainly in the liver o Alpha-keto acids can be converted to acetyl CoA  To enter the TCA cycle or converted to body fat (lipogenesis) o OR converted by the liver to pyruvate to glucose (gluconegogenesis)  Excess can be used for energy production, converted to glucose or stored as fat  Used, in a limited extent, for energy in diets low in kilocalories and/or carbohydrate  Supply less than 10% of our daily ATP needs  Can be derived from dietary protein or breakdown of stored muscle  Proteolysis – breakdown of proteins (from body tissues) into amino acids
More Less

Related notes for NTR 306

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.