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Dr. Greene Week 8 notes

by: Rachel Ferrell

Dr. Greene Week 8 notes NTRI 2000-002

Rachel Ferrell
GPA 4.0

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covers proteins and Vitamins
Nutrition and Health
Michael Winand Greene
Class Notes
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This 7 page Class Notes was uploaded by Rachel Ferrell on Sunday March 6, 2016. The Class Notes belongs to NTRI 2000-002 at Auburn University taught by Michael Winand Greene in Fall 2015. Since its upload, it has received 25 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.

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Date Created: 03/06/16
Rachel  Ferrell   NTRI  2000   3/9/16-­‐3/25/16     Chapter  6:  Proteins     Overview:   • Body  is  made  up  of  thousands  of  proteins   • Contains  nitrogen,  carbon,  hydrogen,  oxygen   • General  functions:   o Regulates  and  maintains  body  functions   o Provides  essential  forms  of  nitrogen  (amino-­‐acids)   • In  developed  world→diet  rich  in  protein   o Issues  with  this?   § Associations  between  protein  intake  and  mortality   § Low  protein→less  mortality  (in  ages  50-­‐65)   § Low  protein→more  mortality  (in  ages  66+)   • In  developing  world→  protein  deficiencies   • Aside  from  water,  protein  makes  up  major  part  of  lean  body  tissue   o About  17%  body  weight   Protein  Structure:   • Amino-­‐acids=  building  blocks  of  proteins   o Nitrogen  bonded  to  the  central  carbon   o Unique  form  of  carbs/fats   • Proteins  in  body→  made  up  of  only  20  amino  acids   o 9  are  essential   § some  are  limiting  (not  found  in  high  amounts  in  food)   o 11  are  nonessential   o New  category:  Conditionally  essential  amino  acids   § Infants  or  disease  states  (need  more  amino  acids  then  usual)   • Sequence  of  amino  acids=  primary  structure   o Leads  to  higher  order  structure   o Leads  to  specific  shape  (native  conformation)   o Shape  =  function   Amino-­‐Acid  Structure:   • Central  carbon   • Acid  group  (carboxyl)   • Amino  group  (nitrogen)   • Side  group  (R-­‐group)→what  makes  each  amino  acid  unique   • Hydrogen   • How  are  they  connected  together?  Peptide  bonds   o 2  amino  acids→dipeptide   o 3  amino  acids→tripeptide   o Many  amino  acids→  polypeptide   o Some  proteins  have  multiple  polypeptide  chains   Disruption  of  Normal  Protein  Structure:   • Denaturation=  when  protein  begins  to  unfold→loses  its  shape/function   o Heat   o Strong  acids/bases   o Heavy  metals   Protein  Primary  Structure:   • Primary  structure→determined  by  genes/DNA  in  cell’s  nucleus   • Info  in  primary  structure  is  transcribed  into  messenger  RNA  (mRNA)   • mRNA  leaves  nucleus→  rough  ER→ribosomes→  get  translated  into  proteins   Protein  Synthesis:   • DNA  coded  instuctions   • Copies  of  codes   o Transferred  to  the  cytoplasm(via  mRNA)   • Amino  acids  added  one  at  a  time   o With  aid  of  transfer  RNA  (tRNA)   • Requires  energy   Central  Dogma  of  Biology:   • DNA→RNA→protein   How  to  change  Protein  Structure:   • Genetic  alerations   • Can  change  proteins  primary  structure   • Silent  mutation=  no  change  in  amino  acid  sequence   • Other  mutations→  do  cause  a  change  in  the  amino  acid  sequence,  therefore  protein/  function   o Leads  to  genetic  diseases   o Sickle  Cell  Anemia   § Single  base  substitution   § One  change  in  amino  acid→changes  hemoglobin  protein  structure   § Hemoglobin  binds  to  oxygen  in  red  blood  cells   § RBC→becomes  sickle  shaped   Digestion  of  Proteins:   • Predigestion→cooking   o Heat  denatures  proteins,  softens  food   • Digestion  begins  in  stomach   o 1.  Acid  (HCL)  denatures  proteins   o 2.    Pepsin  (enzyme)  breaks  peptide  bonds  of  proteins  reslting  in  protein  fragments   § pepsin  is  released  by  cells  in  the  stomach  and  activated  by  the  acidic  environment   o What  controls  pepsin  and  stomach  acid  release?   § Gastrin-­‐  a  hormone   § Released  in  response  to  thinking  about  food  and  chewing  digested  food   • In  the  stomach  is  partially  digested  proteins  and  other  nutrients→chyme   • Movement  into  small  intestine   o Release  of  CCK  (hormone)-­‐chyme  stimulates   o CCK  causes  pancreas  to  release  proteolytic  enzymes  (cleaving/  breaking  proteins  such  as   trypsin  and  chymotrypsin)   o Pepsin  inactivation  (elevated  pH)   • Several  peptidases  are  found  in  the  brush  border  of  small  intestine   • Small  peptides  (2-­‐3  amino  acids  in  length)  and  free  amino  acids  are  absorbed  by  active  transport   • Any  intracellular  peptides  are  digested  by  enzymes  within  cells   Amino  Acid  Absorption   • Taken  up  by  capillaries  and  taken  to  the  liver  via  the  portal  vein   • Liver   o Used  as  the  building  blocks  for  liver  proteins   o Broken  down  for  energy   o Released  into  blood   o Converted  to  nonessential  amino  acids,  glucose,  or  fat   Are  some  Individuals  Sensitive  to  Proteins?:   • Gluten  is  a  protein  found  in  grains  like  wheat,  rye,  and  barley  that  gives  baked  goods  their  doughy,   elastic  structure   • Celiac  disease=  incomplete  gluten  breakdown  in  small  intestine  leaving  small  peptides  and  amino   acids   o Inflammatory  response  to  small  peptides  and  amino  acids   o Autoimmune  response,  genetic   o Prevalence  in  US=  1  in  133   o In  people  with  related  symptoms=  1  in  56   o To  test,  do  a  blood  test  to  test  for  antibodies.  Then,  they  can  do  an  intestinal  biopsy     o ***will  be  a  test  question  on  celiacs   Infant  Digestion  of  Proteins:   • up  to  4-­‐5  months  of  age   o the  GI  tract  is  somewhat  permeable  to  small  proteins.  Whole  proteins  can  be  absorbed     o If  breastfed,  this  allows  antibodies  to  be  passed  from  the  mother  to  baby   o Reccommendations   § Waiting  until  the  infant  is  at  least  6-­‐12  months  of  age  before  introducing  some  foods   that  can  cause  allergies.  Introduce  new  foods  in  a  step-­‐wise  manner   Functions  of  Proteins  in  the  Body:   • 1.)  Producing  vital  body  structures   o body  is  in  a  state  of  constant  protein  turnover=  producing  and  disassembling  proteins   o What  happens  with  protein  inadequacy?   § Producing  proteins  slows  down   § Muscles,  blood,  proteins,  and  vital  organs  decrease  in  size   § Brain  resists  breakdown   • 2.)Maintaining  fluid  balance   o blood  proteins  attract  fluids   o What  happens  with  protein  inadequacy     § Fluid  shifts  into  tissues→edema  (swelling)   • 3.)  Contributing  to  acid-­‐base  balance   o Acts  as  buffers→maintain  pH  within  a  narrow  range   o Keeps  blood  slightly  alkaline  (above  7)   • 4.)  Forming  hormones  and  enzymes   o Hormones   § Communication  between  cells   o Enzymes   § Catalyze  reactions  in  cells   • 5.)  Transport  and  Signaling  Receptors   o Transport   § bring  nutrients  into  the  cell   o Signaling  receptors   § Communication  in  the  cell   • 6.)  Contributing  to  immune  function   o Antibodies  production   o What  happens  with  protein  inadequacy   § Decrease  in  immune  function   • 7.)  Providing  energy   o prolonged  exercise/  calorie  restriction   o however,  fats/carbs  are  primarily  used  for  energy   § because  they  are  efficient→  it  wastes  calories  to  metabolize  amino  acids  for  energy   • 8.)  Forming  glucose   o Amino  acids→converted  to  glucose  when  glucose  is  low   o During  starvation→  muscle  wastes  away  and  edema  results  from  protein  breakdown   o Glucogenic  Amino  Acids=  used  to  make  glucose  (not  every  AA  can  be  used  to  make   glucose)   • 9.)  Contributing  to  Satiety   o makes  you  feel  full   o can  contribute  to  calorie/weight  control   Amino  Acids  Fate  in  Cells:   • breakdown  of  amino  acids   o release  nitrogen  in  form  of  ammonia  (NH3)   o ammonia  converted  to  urea  by  liver   o kidney  converts  urea  into  urine     Protein  Need:   • if  you  aren’t  growing  (adults)   o only  need  enough  to  replace  protein  you  lose  daily   o What  are  you  replacing?   § Normal  protein  breakdown  (protein  turnover)   o Goal=  protein  balance   • Protein  RDA=  0.8  g/kg  of  a  healthy  body  weight   o Ex.  body  weight=  154  lbs   o Divide  by  2.2  lb/kg   o Then  multiply  by  0.8g/kg   o Answer=  56  g  of  protein     • Food  and  Nutrition  Board→upper  range=  35%   • In  the  U.S.   o Men→  100g     o women→65g     o both  eat  more  protein  than  needed   • Western  diet   o 70%  dietary  protein  is  from  animal  sources   o beef,  poultry,  milk,  bread,  cheese   • Issue  with  high  protein  diet?   o Animal  meat   § No  fiber,  few  vitamins/phytochemicals   § High  in  saturated  fat  and  cholesterol   o Red  meat/  processed  mean→colon  cancer   o Can  put  stress  on  kidneys   o Can  lose  calcium  in  urine   Alternatives  to  Protein:   • Vegetarians=  no  meat   • Semi-­‐vegitarians=  no  red  meat   • Veagan=  no  animal  products   o All  use  complementary  proteins   o Nutrient  deficiency  concerns     § Vitamin  B12,  Iron,  Zinc,  Calcium,  Omega-­‐3   • Animal  proteins  tend  to  be  “complete”  or  “high-­‐quality”   o Contains  all  essential  amino  acids   • Plant  proteins  tend  to  be  “incomplete”  or  “low-­‐quality”   o Low  in  one  or  more  essential  amino  acid   Plant  Sources  of  Protein:   • Nuts→trees   • Seeds→  vegetables/flowering  plants   • Legumes→  pods  that  have  one  row  of  seeds   Vegetarian  Diet/  Protein:   • Grains/nuts→  low  in  lysine  (amino  acid)   • Vegetables  and  legumes→  low  in  methionine  (amino  acid)   • Complementary  proteins=  combining  more  proteins  together  to  get  all  essential  amino  acids   Examples  of  some  Complete  Protein  in  Plants:   • Quiona   o Grain  like  crop   • Amarantin   o Seeds,  leafy  greens   • Soybeans   • Buckwheat   Protein  Consumption:   • Can  protein  consumption  be  an  issue  in  general?   o Gluten  sensitivity   o Other  sensitivities   o Food  protein  Allergies   § Immune  system  mistakes  proteins  for  foreign  invaders   § 90%  of  food  allergies     • soy,  peanuts,  tree  nuts,  wheat,  milk,  eggs,  fish,  shellfish   Protein  Calorie  Malnutrition:   • in  the  developed  world:   o diet  is  typically  rich  in  protein   • in  the  developing  world:   o protein  deficiency  is  an  issue   o important  to  focus  on  protein  diet  planning   o stunts  growth   o increase  risk  of  infection   • somewhat  rare  in  developed  countries   o seen  in  certain  populations   Protein  Energy  Malnutrition:   • Maramus=  starvation/  insufficient  protein  and  calories   • Kwashiorkor=  enough  calories  but  not  enough  protein   • Diesases  commonly  found  in  Africa   • What  about  the  US?  Protein  deficiency?   o Only  in  rural  areas;  not  widespread   o Hospital  in-­‐patients   o Long-­‐term  care  residents   o Community  dwelling  adults   o Dialysis  patients   o All  have  in  common?→  older  adults  +65               Chapter  8:  Vitamins:     Definition:   • 1.)  Organic  substances  needed  in  only  small  amounts  for  the  proper  functioning  of  our  body   • 2.)  Essential  (body  doesn’t  make  enough  or  at  all)   • 3.)  Noncaloric   Criteria  to  be  Classified  as  a  Vitamin:   • the  body  in  unable  to  synthesize  enough  of  the  compound  to  maintain  health   • absence  of  the  compound  from  the  diet  for  a  defined  period  produces  deficiency  symptoms   • can  be  reversed  when  the  compound  is  resupplied   • a  compound  does  not  qualify  as  a  vitamin  merely  because  the  body  cannot  make  it   Megadoses  of  Vitamins:   • Megadose   o Beyond  estimates  of  need   o Or  not  in  a  balanced  diet   o 2-­‐10  times  normal  human  needs  (RDA)   o hard  to  do  by  eating  foods,  easy  to  do  with  supplements   • increases  risk  for  toxicity  symptoms     • proven  useful  in  treating  several  non-­‐deficiency  diseases   o Niacin  and  cholesterol   • Issues   o Over-­‐supplementation  can  lead  to  vitamin  levels  building  up  over  time   o Vitamins  can  be  stored  within  the  body   o Which  ones  have  potential  for  reaching  toxicity  levels?   § Fat  soluble  vitamins→especially  Vitamin  A   Vitamin  Preservation:   • The  riper  the  food→the  more  vitamins   • Vitamins  lost  from  the  time  picked  to  the  time  consumed   o Best  to  eat  as  soon  as  possible  after  harvest   • Water  soluble  vitamins  destroyed  by  improper  storage  or  excessive  cooking   o Heat,  light,  air,  cooking  in  water,  alkalinity   • Fresh  is  best,  then  frozen   • How  to  preserve  vitamins  in  food:   o 1.)  Freezing→best  method   o 2.)  Blanching→  also  works   § destroys  enzymes  that  degrade  vitamins  (heat  denatures  proteins)   Two  Classes  of  Vitamins:   • 1.)  Fat  soluble   o vitamins  A,D,E,  and  K   o absorbed  in  chylomicrons   o stored  in  liver  and  fatty  tissue   o not  readily  excreted   • 2.)  Water  soluble   o vitamins  C  and  B   o absorbed  in  capillaries     o in  general  not  stored  to  a  great  degree   o excess  excreted  in  urine   Vitamin  A:   • Consists  of  Retinoids  and  Carotenoids   • Deficiency  or  toxicity  can  cause  severe  problems     o Narrow  range  of  optimal  intakes   • Retinoids   o Three  active  forms  of  Vitamin  A  (performed)   § Retinol   § Retinal   § Retinoic  acid   § Exist  only  in  animal  products   • Carotenoids   o Contained  in  plant  pigments   o Phytochemicals-­‐  polyphenols   o Principle  pigment  for  red,  orange,  yellow,  and  green  colored  fruits  and  vegetables   o Some  are  precursors  to  Vitamin  A   § Can  be  turned  into  Vitamin  A:  Provitamin  A   o Beta-­‐carotene   § Carotenoid  that  can  be  sufficiently  absorbed  and  converted  to  retinol   Functions  of  Vitamin  A  and  Carotenoids:   • Health  of  epithelial  cells  and  immune  function   o Maintains  health  of  epithelial  cells  that  line  internal  and  external  surfaces   § Lungs,  intestines,  stomach,  bladder,  eyes,  skin   o Serve  as  important  barriers  to  infection   • Vision   o Night  blindness=  vitamin  A  deficiency  disorder  that  results  in  loss  of  ability  to  see  under   low-­‐light  conditions   o Vitamin  A  important  for  light-­‐dark  vision  and  color  vision   § Retina  consists  of  rods  and  cones   § rods→detect  black  and  white,  night  vision   § cones→  color  vision   o Carotenoids  for  vision   § Lutein  and  zeaxanthink  in  high  concentrations  in  retina   • Found  in  leafy  greens   • Help  prevent  macular  degeneration   • Food  sources  may  help  decrease  risk  of  cataracts   • Cardiovascular  disease  prevention   o Carotenoids  may  decrease  risk  by  preventing  oxidation  of  LDL   o Recommendation  to  consume  5  serving  a  day  of  fruits  and  vegetables   • Overall  growth,  development,  and  reproduction   o Vitamin  A  binds  to  receptors  on  DNA  to  increase  synthesis  or  proteins  required  for  growth   o Important  for  the  differentiation  and  maturation  of  cells  in  early  fetal  growth   o Deficiency  can  cause  stunted  growth  in  children   • Possible  cancer  prevention   o Potential  benefits  but  also  potential  risks   § Lowers  risk  of  skin,  lung,  bladder,  and  breast  cancer   o Megadose  supplements  pose  potential  risk  for  toxicity   § Not  recommended   o Carotenoids   § Decrease  risk  of  lung  cancer,  oral  cancers,  prostate  cancer  in  men          


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