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Today’s Outline

Today’s Outline. NO TEST! Postponed until Tuesday Hand back first lab assignment Finish up lecture on carbohydrates Hand out study guide Q&A about test Begin Protein lectures. Lecture 6: Carbohydrate Wrap Up and Protein. Will Brown Bio 200 01/19/2012. Objectives and Content.

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Today’s Outline

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  1. Today’s Outline • NO TEST! Postponed until Tuesday • Hand back first lab assignment • Finish up lecture on carbohydrates • Hand out study guide • Q&A about test • Begin Protein lectures

  2. Lecture 6: Carbohydrate Wrap Up and Protein Will Brown Bio 200 01/19/2012

  3. Objectives and Content • Objective: Finish up carbohydrates and begin discussion on protein. Also discuss the test. • Contents: • Carbohydrates – Fiber in the body • Protein • Introduction • Protein synthesis • Protein digestion and absorption

  4. Polysaccharides Fiber Made in plants Indigestible Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Soluble Pectins Amylose Straight chain Pectins Soluble Amylopectin Branched Insoluble Cellulose Cellulose Insoluble

  5. Putting Fiber to Work: the Colon • High fiber diets promote colon health • Adds mass to stool making it easier to excrete • Larger size stimulates stronger muscle contractions • Low fiber diets results in small hard stool that is difficult to pass • Diverticula-small pouches that form between the bands of muscle-think of it as a hernia in the colon • Diverticulosis-asymptomatic pouches • Diverticulitis-painful inflamed pouches, can result in hospitalizations • Numerous studies have shown fiber can reduce colon cancer risk

  6. Putting Fiber to Work • Helps reduce Obesity • Usually takes longer to chew • Makes you feel full but doesn’t supply as many calories-insoluble fiber • Helps regulate blood glucose-slows absorption of digestible carbs • Helps lower cholesterol • Inhibits absorption of cholesterol from intestine • ↓ insulin levels because of effects on blood sugar • Insulin also stimulates cholesterol synthesis in the liver

  7. Carbohydrate Needs • RDA for Carbohydrate = 130g • Should comprise 45-65% of daily calories • Example: for 2000 calorie diet that is between 900 to 1300 calories=~300g • On Nutrition Facts labels they use the 60% to calculate “% carbohydrate” • Look for nutrient dense carbohydrates • Fruit, vegetables, beans, etc. • RDA for fiber = 25g for women, 38g for men • Based on reducing cardiovascular disease • Most americans fall below these limits • Women = 13; Men = 17

  8. Carbohydrate Intake and Health Issues • Ketosis-breakdown of fatty acids • Can result in acid-base imbalance • Lactose intolerance • High fiber diets (>60g/day) – must be accompanied with high fluid intake • Can result in intestinal blockages • Decreased nutrient uptake – Zn+ and Fe+ • Can reduce calories in small children • High Sugar diets – Increases caloric intake but not nutritional intake • Upper limit = 25% of calories from “added sugar”; WHO suggests 10% • Increased weight gain • Insulin spikes that can lead to insulin resistance • Increased cavities (AKA: dental caries)

  9. This ends the material covered by the first exam.

  10. Proteins

  11. What are Proteins? • They are long polymers of Amino Acids that are strung together to form functional structures • Accounts for ~17% of lean body mass • Proteins perform most of the functional parts of cells and in the body • Antibodies are made from 4 different proteins bonded together • Can act as signaling molecules,

  12. Why are proteins important in the diet? • Provides an available form of Nitrogen • Critical in maintenance and regulation of body • Clotting cascade is protein based • Fluid balance • Enzymatic function • Can be used as energy – 4 kcal/g • When not enough are consumed then metabolism slows incredibly • Not enough amino acids to support production of critical proteins

  13. What are Amino Acids? OH H H AcidGroup AmineGroup O = C – C – N – H R Functional Group

  14. OH OH OH H H H H H H H H O = C – C – N – H C – C – N – H O = C – C – N – O = C – C – N – H Peptide Bond = O R R R R H2O

  15. Amino Acids • There are 20 AA that the body needs to function • 11 are “nonessential” with respect to diet • Can be made by the body in appreciable amounts • 9 are “essential” • Can not be made by the body • Some AA are known as “Branched-Chain” AA • Used by muscle to make energy

  16. Protein Synthesis • http://www.youtube.com/watch?v=41_Ne5mS2ls

  17. Protein Synthesis http://bookbuilder.cast.org/bookresources/41/41887/159540_1.jpg

  18. Protein Structure • Primary – the amino acid sequence • Secondary – Alpha helix or Beta pleated sheet Ala-Gly-Val-Ala-Phe-Iso-Gly-Asp http://www.flashcardmachine.com/biochemistrychapter-6.html http://click4biology.info/c4b/7/images/7.5/betapleated.gif

  19. Protein Structure • Tertiary – a-helix and b-pleated sheet that is folded to form a functional structure • Quaternary – two or more tertiary structures that combine to form a functional protein Tertiary structure Quaternary structure http://chemistry.umeche.maine.edu/CHY431/5abp-1.jpg http://molbiol-tools.ca/Protein_tertiary_structure.htm

  20. Amino Acid Requirements • Adults = 11% of total proteins must be essential AA • Infants through preschool = 40% of protein must be essential AA • Later childhood = 20% • A typical diet has 50% of protein as essential AA

  21. Protein Show DownPlant vs. Animal • 2 different sources • Plant – known as low quality or incomplete protein • Plant proteins usually low or deficient in 1 of the 9 essential AA • Animal – known as high-quality protein • Animal tissue closely resembles our own tissue; easy to meet human protein needs • If low in one of the 9, then all protein synthesis stops… Why?

  22. Protein Synthesis http://bookbuilder.cast.org/bookresources/41/41887/159540_1.jpg

  23. Protein Show DownPlant vs. Animal • Can plant proteins meet the protein needs? • Yes, combining proteins from more than one source you can make up for deficiencies in each other • Called complimentary proteins • Mixing up the diet makes up for deficiencies • Most Americans could eat more vegetable protein • Contain no cholesterol and little saturated fat • Vegetables also supply a number of other essential nutrients • Good sources of plant protein: nuts and legumes

  24. Plant Protein: Nuts and Legumes • Nuts – Pecans, Pistachios, and Walnuts • Hard shell with edible kernel • Grows on a tree • For a 1 oz. serving • 14-19 g of fat • 160-190 kcal • 6-10 g protein • Legumes – Kidney Beans, Peanuts, Black-eyed peas • Pods that grow in a row • Most are the dried seeds we know as beans • For a ½ c serving • 100-150 kcal • 5-10 g protein • <1 g of fat • 5 g fiber

  25. Protein Digestion

  26. Protein Digestion • Where does protein digestion begin? • Similar to carbs, it begins with cooking • Cooking denatures proteins; making them unfold • Remember structure=function • Begins breaking down connective tissue • Also makes them safer to eat by killing pathogenic organisms • Unlike carbs, no enzymatic breakdown in the mouth; only mechanical breakdown

  27. Protein Digestion: Stomach • Enzymatic breakdown begins • Pepsin – breaks polypeptide chain into smaller peptides and amino acid chains • Under the control of the hormone Gastrin • Gastrin also increases stomach acid production • Stomach acid can also hydrolyse the peptide bond • To a lesser extent then Enzymatic breakdown

  28. + H2O + 2 H+ OH OH OH H H H H H H H H O = C – C – N – O = C – C – N – H O = C – C – N – H C – C – N – H = O R R R R + H H

  29. Protein Digestion: Small Intestine • Protein, as part of the chyme, moves into duodenum • Presence of protein in the SI causes release of hormone Cholecystokinin (CCK) from wall of SI • Acts on pancreas to release enzymes such as Trypsin • Pancreatic enzymes break down proteins into amino acid chains of ≥3 • Enzymes released from the SI wall causes further breakdown • Also can be broken down inside absorptive cells

  30. Protein Absorption

  31. Protein Absorption • Knowing what you know about absorption, what method do you think is used for amino acid uptake? • Active transport – AA are to big and to polar for diffusion • Enter the liver via hepatic portal vein • Combined to make protein • Released into blood stream • Broken down for energy • Converted to nonessential AA, glucose or fat • Fat is the last thing made

  32. Protein Absorption: InfantsA Special Case • Up to 5 months in age SI is more permeable than in later infancy • Whole proteins can be absorbed into the body • Antibodies from mothers milk • It is recommended that allergenic foods be given after 6 months in age • Cow’s milk • Eggs

  33. How does the body use proteins?

  34. Protein: Vital Structures • Protein make up most of the structure with in the body; ie: muscle, connective tissue, extra-cellular matrix, etc. • If protein is not the main structure than protein does impacts it in some way; ie: proteins and enzymes involved in bone remodeling

  35. Protein: Vital Structures • Your body is in a constant state of change • Build up vs. Break down • “Each kind of tissue has its own turnover time, related at least partially to the workload endured by its cells. Epidermic cells, forming the easily damaged skin of the body, are recycled every two weeks or so. Red blood cells, in constant motion on their journey through the circulatory system, last only 4 months. As for the liver, the human body's detoxifier, its cells' lives are quite short - an adult human liver cell has a turnover time of 300 to 500 days. “ - h ttp://dbs.cordis.lu/cgi-bin/srchidadb?C ALLER=NHP_EN_NEWS&ACTION=D&SESSION=&RCN= EN_RCN_ID:24286 Previous Item Back to Titles Print Item

  36. Protein: Vital Structures • Proteins breakdown • Enzymes, like amylase, that are secreted into the intestines are digested and the amino acids reused • Certain proteins as part of their function are consumed by what ever process they are involved in – CYP3A4 and drug dexification • Old proteins suffer environmental damage so are recycled • Proteins can be deliberately targeted for breakdown – ubiquitination • Your body degrades and recycles about 250g of protein a day

  37. Proteins: Fluid Balance • Blood pressure forces fluid out of the capillaries • Capillaries are semi-permeable membrane • Hydrostatic pressure • Proteins are to large to be forced out of the capillary • As the protein concentration inside ↑, it draws back the water • Osmotic pressure

  38. Proteins: Other Key Functions • Act as buffers in the blood or secrete buffers into the blood • Provide immunity – antibodies • Sugar regulation – glycogen breakdown done by enzymes, or protein can be catabolized into glucose • Cause satiety – makes you feel fuller longer

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