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163 Cards in this Set
- Front
- Back
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What are the essential amino acids?
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Histidine, Isoleucine, Leucine, Lysine, Methionine/Cystine, Phenylalanine/Tyrosine, Threonine, Tryptophan, Valine
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Which two amino acids do humans not synthesize from scratch?
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Cystine and Tyrosine
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Tyrosine is made from what amino acid?
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Phenylalanine
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Cystine is made from what amino acid?
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Methionine
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What amino acid is essential for PKU patients?
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Tyrosine
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What are the four types of bonds in tertiary proteins?
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Hydrophobic Interactions
Hydrogen bonds Ionic Interactions Disulfide bonds |
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What is the general structure of amino acids?
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Central C
Amino group Carboxylic Acid R group side chain (C,H,O,N and S) |
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What are the different types of amino acids?
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acidic, basic, aliphatic/branch, aromatic, and sulfur
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Define Transamination
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process for synthesizing nonessential amino acids
carbon skeleton from a metabolic cycle accepts amino group to become an amino acid (Vitamin B6 required) |
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What does primary protein organization consist of?
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peptide chain- base pairs- simple sequence
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What does secondary protein organization consist of?
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coiling- alpha helix, beta sheets
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What does tertiary protein organization consist of?
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3D interactions among side chains
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What does quaternary protein organization consist of?
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more than one protein connected
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Can a protein still function if the structure has been changed?
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Protein will no longer function
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What does protein denaturation entail?
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breaks hydrogen bonds
breaks down tertiary structure |
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Essential vs. Non-essential
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tryptophan- essential, least common
tyrosine- depends if you have enough phenylalanine |
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High Quality (complete) protein
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provides 9 EAAs in proportion for human use
usually from animal sources |
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Low quality (incomplete) protein
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EAAs pattern does not match human requirements
typically from plant sources one or more EAAs low or missing (e.g. corn low in tryptophan and lysine) |
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Limiting Amino Acids
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EAA present in the least sufficient amount
"All or none" law Nitrogen excreted in urea |
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Protein complementation
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Combine foods with different amino acid patterns to supply EAAs in proper proportion
e.g. grain (low in lysine) + bean (low in methionine) = complete protein yield sufficient EAAs eaten within 24 hours Rarely a problem in the US |
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Which food has the highest quality protein source of tryptophan?
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Meat
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Which food has the highest quality protein of leucine?
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Grain
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Which food has the highest quality protein of methionine?
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Grain
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Which food has the highest quality protein of lysine?
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Meat
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Examples of complete protein meals?
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corn and beans
wheat pita bread and lentils cashew nuts and tofu rice and black beans |
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What is the limiting amino acid of beans and legumes?
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methinonine, tryptophan
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What is the limiting amino acid of tree nuts and seeds?
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methionine and lysine
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What is the limiting amino acid of grains (wheat, rice and oats)?
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lysine
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What is the limiting amino acid of vegetables?
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methionine and lysine
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What is the AMDR of protein?
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10-35% of calories
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Biological Value
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ratio of N retained to N absorbed
measures how efficiently the absorbed food protein can be turned into body tissue how close is the food's AA pattern to that of tissues |
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Protein Efficiency ratio (PER)
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FDA uses for labeling regulations for infant food
compares the weight of gain of a test subject divided by its intake of a particular food protein during the test period. |
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Chemical Score
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EAA in the food divided by an "ideal" amount for that essential AA
the lowest EAA score is the CS for that food |
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Protein Digestability Corrected AA Score
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= chem score x digestibility
(0-1) 1=milk, eggs, soy protein nutrition facts panel rarely list |
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How many essential amino acids are there?
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nine
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Adults need only __% of total protein as essential amino acids
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11%
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Infants and preschool need ___% of total protein as EAA, to accommodate growth and development.
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40%
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The typical diet supplies __% of protein as essential amino acids.
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50%
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Rationale for protein RDA
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Through N balance studies, amount of protein required for nearly all adults to maintain protein equilibrium.
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What is the RDA for protein
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0.8 gm of protein / kg healthy BW/day (56 for 70 kg man)
Increased 25 g/d 2nd and 3rd trimester of preg. lact. |
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Can excess protein be stored as protein?
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NO!
Nitrogen is excreted and carbon skeleton is metabolized |
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Do athletes need more protein?
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no!
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DGA foci for protein
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increase intake of fruits, vegetables, whole grains, and low-fat milk
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Protein function- energy
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5-10% of energy used in body (expensive energy)
prolonged exercise if there are insufficient total kcalories, then dietary (and body) protein is used for energy |
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Protein function- glucose formation
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gluconeogenesis for brain and RBC between meals and low CHO diets
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Protein function- structure
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CT, bone matrix, epidermal cell walls (skin), lipoproteins, antibodies, etc
collagen, actin, myosin, plus hemoglobin make up 50% of the body's protein |
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protein function- protein hormones and enzymes
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insulin, pituitary hormones
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Protein function- fluid balance
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Normal protein levels in the blood keep the plasma fluids inside the blood vessels. If the protein levels go down (deficiency) then the plasma fluids can leak out into the tissues and cause edema or swelling.
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Nitrogen Balance
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positive- bodybuilder, pregnant women, children
equilibrium- healthy adult negative-elderly, bedridden, astronauts |
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What are the major uses of Amino Acids in the body?
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fat, glucose, energy, protein synthesis
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What is deamination?
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amine groups taken off turn into urea then into urine
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What is kwashiorkor?
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apathy, diarrhea, listlessness, no growth, infections, changes in hair color, massive edema with subcutaneous fat
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What is Marasmus
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wasting, skin and bones, no subcutaneous fat
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What happens with excess protein?
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45% kcal from protein – weakness, nausea, diarrhea, death (“rabbit starvation”)
Maximum rate of urea synthesis/excretion at 250 g protein/d (approx. 40% kcal) High protein does not prevent loss of lean tissue during negative energy balance. |
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Effects of a high protein diet?
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Decreased fiber
Decreased folate Decreased Mg Decreased phytochemicals Increased saturated fat Increased cholesterol Increased Ca loss in urine (minimal) Increased colon CA (link to red meat, heterocyclic amines during cooking) Increased excretion of N (concern for those in early stages of kidney disease, e.g. diabetics) |
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For what diets is osteoporosis a risk?
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for diets with protein and vegetarian diets
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Vegetarian advantages
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Lower rates of some chronic diseases (CHD, hypertension, type II diabetes, obesity, some cancers)
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Vegetarian disadvantages
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Nutrient deficiencies if uninformed – B12, Fe, Zn
Deficiencies and growth retardation in children of uninformed vegetarian mothers Less nutrient-dense sources of lysine, methionine, vitamins B12, D, Ca, Fe, Zn, riboflavin |
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What is the American Dietetic Association opinion on vegetarianism
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Well-planned vegetarian diets are appropriate for all stages of life and can have all of the required nutrients
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Structure of ethanol
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HO-CH2-CH3
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What is the ADH pathway of alcohol?
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Ethanol -> Acetaldehyde -> Acetyl CoA -> Citric Acid Cycle -> NADH -> ETC -> ATP
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What is the MEOS pathway of alcohol?
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Ethanol becomes Acetaldehyde with the NADPH and produces water
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Why don't alcohol and drugs mix?
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MEOS metabolizes “xenobiotics” (drugs, carcinogens, alcohol)
alcohol is hazardous to the body if not quickly metabolized, so the drugs have a prolonged effect |
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Metabolism of alcohol is similar to metabolism of what other substance?
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fat
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Important benefits of alcohol usage?
(for less than one drink per day) |
increases HDL cholesterol
decreases blood clotting relaxes blood vessels decreases blood pressure |
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What are the major risks of alcohol usage?
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heart rhythm disturbances
heart muscle damage increased blood triglycerides and homocysteine increased blood clotting increased blood pressure risk of diabetes osteoporosis brain and skeletal muscle damage increased risk for cancer |
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By how many years does alcohol abuse effect life expectancy?
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15 years reduced
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DGA foci for alcohol
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drink in moderation (1 for women, 2 for men)
some people should not drink alcohol alcohol can impair function |
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What did President Faust say about alcohol and addictions?
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Some people seem to be born with a weakness for these substances so that only a single experimentation will result in uncontrollable addiction.
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What is the order of the GI tract?
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oral cavity -> esophagus -> stomach -> small intestine (duodenum, jejunum, ileum) -> large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon) -> rectum -> anus
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What is the order of the sphincters?
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lower esophageal/cardiac -> pyloric -> sphincter of Oddi -> ileolcecal
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what is the function of the cardiac sphincter?
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prevents backflow of acid from the stomach
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what is the function of the pyloric sphincter?
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controls flow of chyme into the small intestine
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what is the function of the sphincter of oddi?
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control the flow of bile into the small intestine
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what is the function of the ileocecal sphincter?
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prevents backflow from the large intestine into the small intestine
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What is peristalsis?
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movement of food through GI tract
in the esophagus and intestine wave pushing food along |
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What is segmentation
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mixing and churning food
no net movement |
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What happens inside the stomach and how long does it take?
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2-3 hours
store, mix, dissolve, and continue digestion of food dissolve food particles with secretions kill microorganisms with acid release of protein-digesting (pepsin) enzyme lubricate and protect stomach surface with mucus regulate emptying of dissolved food into Small intestine |
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What happens inside the small intestine and how long does it take?
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3-10 hours
mixing and propulsion of contents lubrication of mucus digestion and absorption of most substances using enzymes made by the pancreas and Small intestine |
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What happens inside the large intestine and how long does it take?
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24-72 hours
mixing and propulsion of contents absorption of sodium and potassium and water storage and concentration of undigested food lubrication with mucus formation of feces |
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What are the three accessory organs?
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liver, gallbladder and pancreas
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What is the function of the liver?
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Production of bile to acid in fat digestion and absorption and receive nutrients from portal vein
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What is the function of the gallbladder?
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storage, concentration and later release of bile into the small intestine
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What is the function of the pancreas?
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secretion of sodium bicarbonate and carbohydrate, fat, and protein digesting enzymes
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Where is salivary amylase produced, what are its substrates and what are the end products?
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salivary glands
substrate: starch, glycogen products: maltose and dextrins |
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Where is pepsin produced, what are its substrates and what are the end products?
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stomach glands
substrate: protein products: peptides and peprones |
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Where is gastric lipase produced, what are its substrates and what are the end products?
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stomach glands
substrate: triglycerides products: fatty acids, monoglycerides |
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Where are trypsin and chymotrypsin produced, what are its substrates and what are the end products?
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pancreas
substrate: protein and peptides products: polypeptides, smaller peptides chymotrypsin- more coagulating |
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Where is carboxypeptidase produced, what are its substrates and what are the end products?
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pancreas
substrate: polypeptides products: smaller peptides, free amino acids |
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Where is pancreatic amylase produced, what are its substrates and what are the end products?
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pancreas
substrates: starch, glycogen, dextrins product: maltose |
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Where is lipase produced, what are its substrates and what are the end products?
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pancreas
substrate: triglycerides products: monoglycerides, free fatty acids |
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Where is aminopeptidase produced, what are its substrates and what are the end products?
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intestinal wall
substrate: peptides products: amino acids, smaller peptides |
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Where is maltase produced, what are its substrates and what are the end products?
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intestinal wall
substrate: maltose product: glucose |
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Where is sucrase produced, what are its substrates and what are the end products?
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intestinal wall
substrate: sucrose product: fructose, glucose |
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Where is lactase produced, what are its substrates and what are the end products?
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intestinal wall
substrate: lactose product: glucose, galactose |
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Where is enterokinase produced, what are its substrates and what are the end products?
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intestinal wall
substrate: trypsinogen product: trypsin |
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What is cystic fibrosis?
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a hereditary disorder characterized by lung congestion and infection and malabsorption of nutrients by the pancreas
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What is a zymogen?
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inactive enzymes (synthesized with extra AAs)
activated when, where needed |
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What do chief cells make?
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pepsinogen
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What do goblet cells make?
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mucus
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What do parietal cells make?
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HCl
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What is the emulsifier of the digestive tract?
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liver makes bile
gallbladder stores bile pancreas adds base to buffer |
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What is the difference between bile acids and bile salts?
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bile acids are protonated and bile salts are ionized
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What are the causes of gall stones?
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blockage
inadequate digestion limited absorption acids and gases in colon foamy, greasy stools |
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What is CCK and what is its function?
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stimulates release of pancreatic enzymes, bile from gall bladder
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What is gastrin and what is it's function?
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triggers stomach release of HCl, pepsinogen, increase motility
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What is GIP and what is its function?
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signals stomach to limit gastric juices, slow motility
released from small intesetine |
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What is secretin and what is its function?
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stimulates release of pancreatic bicarbonate
small intestine in response to chyme |
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What are the types of absorptive mechanisms?
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passive diffusion
facilitated absorption active transport penocytosis - forms vesicles |
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What does the stomach absorb?
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20% of total alcohol
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What does the small intestine absorb?
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calcium, magnesium, iron, fat-soluble vitamins, glucose, water-soluble vitamins, amino acids, 80% of alcohol, fats, sodium, potassium, water, bile, vitamin B12
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What does the colon absorb?
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sodium, potassium, water, acids and gases
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How are the monosaccharides absorbed?
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glucose- active transport
galactose- active transport fructose- facilitated diffusion requires sodium |
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How are proteins and amino acids absorbed?
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amino acids, dipeptides and tripeptides absorbed
about 11 different transport proteins, categories of amino acids only amino acids transported into portal vein immature digestive tract in infants may predispose to allergies by absorbing whole proteins |
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How are lipids absorbed?
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large fat droplets enter SI after meal
bile acids and lecithin emulsify fats into smaller particles, especially bile acids lipase breaks down fat products are absorbed through villi via micelles and reform into triglycerides combine to form chylomicrons |
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Process of cell sloughing and disease
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cells lifespan 2-5 days
replacement requires nutrients SI rapidly deteriorates during nutrient deficiency, allergic reaction, infection, chemotherapy downward spiraling cycle of malnutrition |
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What does gastrin do?
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stimulates parietal cells to produce HCl
stimulates chief cells to produce pepsinogen |
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How much protein per day should a body builder get?
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.8g protein/kg healthy body weight/day
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Why are plant protein sources better than animal protein sources?
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plants also provide fiber, vitamins and minerals
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What is nitrogen needed for in the body?
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to help make protein for body cells and other stuff
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What are some functions of proteins?
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buffers, body structures, provide energy
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How does dietary protein help the blood?
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To put proteins in the blood to create osmotic pressure
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Biological value
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the amount of N retained/the amount of N absorbed
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What happens when serum protein concentration is decreased?
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nutritional edema
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What are the hairlike projections that cover the microvilli of absorptive cells in the small intestine?
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glycocalyx
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What does the colon absorb?
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minerals-sodium and potassium
kcal from bacterial metabolism gases from bacterial metabolism water |
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What is the process of digesting fat?
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enters the small intestine
emulsified broken down by lipase absorbed |
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Which hormone stimulates the gallbladder to release bile acid?
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Cholecystekinin (CCK)
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What does pepsin do?
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breaks proteins into shorter peptides
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T/F are enzymes activated in the place that they were produced?
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False! Then you would digest yourself! They are activated by compounds when they get to the right place
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Define prebiotics:
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they consume substances that favor colonization of the GI tract by beneficial bacteria
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Define probiotics:
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they consume live bacteria that have beneficial effects in the GI tract
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Transamination requires what vitamin
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vitamin B6
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What does the citric acid cycle yield?
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NADH, FADH2, GTP
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What two vitamins does the citric acid cycle require?
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niacin and riboflavin
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What moves fatty acids from cytosol to mitochondria?
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carnitine
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What are the products of beta-oxidation?
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AcetylCOA, NADH, FADH2
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Why do you need carbs to use fat for energy?
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fat- produces AcCOA, need more than that to run TCA
carbs- produce oxaloacetate which you need to run TCA |
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Where do the electrons from the ETC end up?
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They go to oxygen to form water
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What enters the citric acid cycle with Acetyl-CoA
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glycolysis-bridge
some amino acids beta oxidation |
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Can fatty acids make glucose?
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fatty acid -> acetylCoA
acetyl-CoA CAN'T become pyruvate, so it can't become glucose |
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Why do we get more energy from fatty acids than from glucose?
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fatty acids are more reduced so you get more energy
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Do long chain fatty acids and short chain fatty acids go to the same place?
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short chain go to the portal vein
long chain go through the lymph system |
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What does pancreatic amylase do?
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digests starches into maltose
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Where do maltase, sucrase and lactase work?
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the cells of the small intestine
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Where do the protein digesting enzymes come from?
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the pancreas
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What vitamins are used to convert pyruvate to acetyl-CoA?
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niacin, riboflavin, pantothenic acid, thiamin
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What are ketogenic amino acid skeletons converted to?
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acetyl CoA
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What happens to glucogenic amino acid skeletons?
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go to the TCA cycle OR
glycolysis |
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What is rabbit starvation?
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the majority of your calories come from protein, so you get urea poisoning
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How efficiently is glucose converted to ATP?
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>40%
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Which alcohol metabolic pathway is utilized when you don't drink a lot of alcohol?
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Alcohol Dehydrogenase pathway
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How is alcohol metabolized?
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it is converted to acetyl-CoA and enters the citric acid cycle
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Glycogenolysis
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glycogen + lysis (to cut)
breaking down glycogen to produce glucose |
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Glycolysis
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breaking down of glucose to produce pyruvate
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gluconeogenesis
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production of glucose from non-carb sources
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glycogenesis
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the joining of glucose molecules to produce glycogen
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lipogenesis
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the building of fatty acids from acetyl-CoA
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ketogenesis
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the production of acetone from acetyl-CoA
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oxidative phosphorylation
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production of ATP from energy liberated in oxidation reactions
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What does secretin do?
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releases bicarbonate
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Where is aminopeptidase secreted?
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the small intestine
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Study amino acids
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get your notes out from your folder!
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