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Biochem Flashcards

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1
Q

Recommended Dietary Allowance (RDA)

A

Amounts of nutrients that will provide satisfactory levels of nutrients for most people (2 STDs above average)
Categorized based on sex and age

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2
Q

Dietary Reference Intake (DRI)

A

New dietary guidelines
Goal is to prevent nutrient deficiency and reduce risk of chronic diseases
Includes revised RDA, plus EAR, AI, and UL

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3
Q

Estimated Average Requirement (EAR)

A

Nutrient intake that is estimated to meet the needs of 50% of the people in a designated group

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4
Q

Adequate Intake (AI)

A

Nutrient intake that appears to sustain good health in a group of people
For nutrients that haven’t received enough scientific study

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5
Q

Tolerable Upper Level Intake (UL)

A

Highest level of a nutrient that will pose no risk of harmful effects for 98% of population

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6
Q

MyPlate

A 
Simple nutritional messages
Half of plate fruits and veggies
Balance calories
Avoid oversized portions
Make half of grains whole
Drink water
Compare sodium
Switch to fat free/low fat milk
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7
Q

Malnutrition

A

Disorder of nutrition resulting from imbalance or insufficient diet OR defective assimilation or utilization of nutrients
Both overnutrition AND undernutrition can cause problems

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8
Q

calorie

A

Amount of energy needed to raise temp of 1 g H2O by 1 deg C (15 –> 16 deg C)
1 kcal = 1000 cal = 1 Cal = 4.18 kJ

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9
Q

Respiratory quotient

A

Used to determine energy contribution from 1 type of nutrient in a mixed diet
RQ = vol CO2 produced or exhaled/vol O2 utilized or inhaled
RQ carb = 1, RQ protein = 0.8, RQ fat = 0.7

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10
Q

Daily energy expenditure

A

Amount of energy expended doing daily activities
To calculate:
1. Determine BMR and calculate daily (24 hr) energy requirement for BMR
2. Correct for 10% decrease in BMR during sleep (subtract 10%)
3. Determine energy requirements for daily activity (from table) for remaining hours (not sleeping)
4. Correct for thermogenesis (add 10% for mixed diet)
5. Add

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11
Q

Direct Calorimetry

A

Determine amount of energy in food by combusting in calorimeter and determining amt of heat evolved in combustion (via thermometer)
Measures heat released from physical combustion of a food
Gives higher protein value b/c protein contains 16% N and is incompletely oxidized in the body (mostly excreted as urea, still contains unreleased energy)
Carbs = 4 kcal/g = 17 kJ/g
Protein = 4 kcal/g = 16 kJ/g
Fat = 9 kcal/g = 37 kJ/g
Alcohol = 7 kcal/g = 29 kJ/g

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12
Q

Indirect Calorimetry

A

Estimates caloric yield in body by measuring O2 consumed, CO2 produced, and N eliminated
Gives lower protein value b/c protein is incompletely oxidized in body

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13
Q

Basal Metabolic Rate (BMR)

A

Energy expended to sustain basic life, involuntary life function (respiration, cardiac function, nerve function, etc.)
Depends on lean muscle mass

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14
Q

Thermic effect of food OR dietary induced thermogenesis (DIT)

A

Extra heat produced when food is ingested b/c of work of digestion, absorption, and distribution of nutrients
Energy is lost from food and correction must be made when determining body needs
“Cost” of metabolizing food

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15
Q

Basal energy expenditure (BEE)

A

Calculated based on height, weight, age

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16
Q

Major energy expenditures in human body (3)

A

Basal metabolism
Physical activity
Thermic effect of food

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17
Q

Pepsin

A

Secreted by chief cells in stomach in zymogen form
Digests proteins to polypeptides and AAs
Cleaves at N-terminus of hydrophobic (Phe, Tyr, Leu)

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18
Q

Trypsin

A

Produced in pancreas
Stimulated by cholecystokinin
Acts in duodenum
Activated from zymogen form by enteropeptidase
Hydrolyzes proteins
Activates chymotrypsin
Cleaves at C-terminus of basic (Arg, Lys)

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19
Q

Chymotrypsin

A

Produced in pancreas
Acts in duodenum
Activated from zymogen form by trypsin
Hydrolyzes proteins (primarily w/ aromatic ring)
Cleaves at C-terminus of hydrophobic (Phe, Tyr, Trp, Leu, Met)

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20
Q

Elastase

A

Produced in pancreas
Acts in duodenum
Breaks down elastin protein
Cleaves at C-terminus of small (Ala, Gly, Ser)

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21
Q

Carboxypeptidase

A

Produced in pancreas
Acts in duodenum
Activated from zymogen form by enteropeptidase
Cleaves proteins at C-terminus

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22
Q

Aminopeptidases

A

Cleave proteins at N-terminus

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23
Q

Glutathione (GSH)

A

Tripeptide of gamma glutamate, cysteine, and glycine
Antioxidant (counteracts effects of ROS)
Mediates non-specific energy dependent transport of AAs in cells of intestine and kidney

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24
Q

gamma-Glutamyltransferase (GGT)

A

Transfers gamma-glutamyl functional groups from GSH to AA outside cell –> causes transfer of AA across cell membrane
Resynthesis of GSH

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25
Glutamate
Oxidative deamination to form free NH4+ when energy is low (allosteric activation by ADP) Synthesis from alpha-ketoglutarate and free NH4+ when energy level is high (allosteric activation by ATP)
26
Urea cycle
NH4 + Aspartate + CO2 + 3ATP --> Fumarate + Urea + 2ADP + 2Pi + 1AMP + PPi Takes place in liver Energetically expensive
27
Essential Amino Acids
Body can't make or can't make in sufficient amounts, must be taken in from diet ``` Phenylalanine Valine Threonine Tryptophan Isoleucine Methionine Histidine Arginine Leucine Lysine ```
28
Complete proteins
Maintain life and normal growth as sole protein source
29
Partially complete proteins
Maintain life, but not growth
30
Incomplete proteins
Cannot maintain life
31
Chemical store
EAA of a test protein are compared to egg protein (high quality standard) to determine which AA gives largest % deficiency Essentially, the "limiting" AA CS = mg EAA/g test protein/mg EAA per g egg protein x 100%
32
Biological value
Measures % of absorbed AA retained for protein synthesis during growth BV = Dietary N - (Urinary N - Urinary No) - (Fecal N - Fecal No) / Dietary N - (Fecal N - Fecal No) x 100%
33
Digestibility
% of food nitrogen absorbed | D = food N eaten - (fecal N - fecal No)/ food eaten x 100%
34
Protein Digestibility Corrected Amino Acid Score (PDCAAS)
measures limiting AA, but compares it to human requirement of 2-5 yo instead of egg, measures supply of EAA to meet human needs, takes into account digestability
35
Complementary Proteins
2 poor quality proteins that differ in limiting EAA will form higher quality, more adequate protein when mixed Ex. beans (60% Met, 130% Lys) and wheat (95% Met and 40% Lys)
36
Sparing effect
some nutrients can reduce/spare requirements of another by fulfilling one of the demands of the second nutrient (in whole or part) Cystine or cysteine spares methionine (S) Tyrosine spares phenylalanine Carbs spare protein
37
Available carbs
Can be digested and absorbed for use calorically or to make other metabolic products
38
Unavailable carbs
Largely indigestible, provide bulk in diet, aid in elimination Soluble- gums and muscilages as nonstructural plant components, pectins as parts of fruits, resistant starches Insoluble- cellulose in place cell walls
39
Dietary fiber
Comes from plant sources, remains after breakdown in digestive tract Soluble- form gels, delay gastric emptying, slow transit through intestine, decrease nutrient absorption Insoluble- speed up transit time, absorb water, create bulk in feces
40
Crude fiber
remains after acid and alkaline digestion of food in lab | Less than dietary fiber
41
Added fiber
isolated, nondigestible carbs that are added to foods and have beneficial physiological effects in humans
42
Exchange groups
List of foods and serving levels that have approx. same composition of other members of group Allows selecting exchanges w/o extensive calculations Fruits, veggies, starch, milk, meat, fat
43
Glycemic index
Ability of carb foods to raise blood glucose Determined by comparing test food w/ glucose Generally correlated to how highly processed carbs are
44
Glycerides (triglycerides)
``` Store calories most efficiently Can be converted to cholesterol, phospholipids, and other lipids when required for building material Part of adipose tissue Protects/pads skeleton and vital organs Heat/cold insulation ```
45
Phospholipids
Form interior and exterior of cell membrane | Precursors for prostaglandins, leukotrienes, thromboxanes
46
Sterols (cholesterol)
Form interior and exterior of cell membrane | Precursors for bile acids, steroid hormones, vitamin D
47
Essential fatty acids
w3 and w6 polyunsaturated fats | Absence from diet causes dermatitis, alopecia, thrombocytopenia, growth retardation
48
Interconversion of FAs
``` Linoleic acid (18:2 ω6) can be desaturated and elongated to arachidonic acid (20:4 ω6) Linolenic acid (18:3 ω3) can be substited for linoleic acid (not converted) Oleic acid (18:1 ω9) will be elongated to 20:3 ω9 FA (no function) in absence of linoleic and linolenic acid Arachidonic acid corrects most EFA deficiencies ```
49
Trans fatty acid
Double bond is trans (happens during saturation process) --> no bend, like a saturated FA Higher MP Increased LDL/HDL ratio Interferes w/ desaturase that catalyzes production of arachidonic acid
50
Body Mass Index
body weight (kg)/height^2 (m) High BMI correlated w/ increased risk of hypertension, dyslipidemia, sleep apnea, female infertility, CVD, osteoarthritis, adult-onset diabetes Healthy <25
51
Satiety
Ventromedial hypothalamus controls eating, responds to bedta agonists
52
Propanolol
Beta agonist that induces eating
53
Isoproterenol
Inhibits feeding
54
Set point theory
Internal mechanism regulates amount of body fat that one carries Body eats to regain whatever amount the body is "set" for or will stop to lose weight until this genetically programmed level is achieved - Exercise lowers set point - Regaining lost weight heightens set point
55
Leptin
Released by adipocytes whose level indicates level of fat in body Stimulates hypothalamus to release neuropeptides to regulate food intake and metabolic activity Inhibited by sleep deprivation Weight gain causes increase in leptin, which decreases food intake and increases energy expenditure
56
Ghrelin
Short term Secreted by parietal cells in stomach fundus Acts on hypothalamus Causes release of GH and increase of food intake Stimulated by fasting, hypoglycemia, sleep deprivation Inhibited by food intake, hyperglycemia, obesity, bariatric surgery
57
Peptide YY
``` Short term Secreted by ileum and colon Acts on hypothalamus Suppresses appetite, lowers food intake Slows down passage of nutrients through gut Opposes ghrelin ```
58
Orexin (A and B)
Produced in lateral hypothalamus Acts on hypothalamus Stimulates appetite an causes commencement of eating Dysfunction causes sleep disorder narcolepsy
59
Effect of fructose on metabolism
Fructose is normally absorbed slow, but paired with glucose (in sucrose) it is absorbed quickly Once in the blood, very efficiently taken into liver (glycemic index is low b/c it doesn't stay in blood) Doesn't go through same pathway as glucose, but produces pyruvate and enters TCA cycle Citrate has nothing to inhibit w/o glycolysis (loses feedback inhibition) Citrate makes more and more FA instead of glycogen Also promotes transcription factors that enhance all these pathways Lipid droplets accumulate in liver
60
Toxic minerals
``` Copper Fluoride Molybdenum Selenium Arsenic ```
61
Selenium
tRNA associated w/ serine is enzymatically converted to selenocysteine, mRNA signals it to insert at neighboring UGA codon Function: antioxidant, regulates thyroid function, contributes to immune response
62
``` Vitamin A (Active form, biological function, deficiency diseases, toxicity, sources) ```
Fat soluble Active form: alcohol (retinol), acid (retinoic acid), aldehyde (retinal) Biological function: vision (rhodopsin), differentiation of epithelial cells (normal mucosal secretion), growth/reproduction (spermatogenesis) Deficiency: skin lesions, night blindness, infection, Xeropthalmia Toxicity: Polar bear syndrome- rash, hair loss, hemorrhage, birth defect, fracture, liver failure, death Sources: animal foods
63
Pro-vitamin A | Active form, biological function, sources
Fat soluble Active form: B-carotene (2 molecules of A) Biological function: antioxidant Sources: plants
64
``` Vitamin D (Active form, biological function, deficiency diseases, toxicity, sources) ```
Fat soluble Active form: 1,25-dihydroxyvitamin D3 Biological function: maintain homeostasis of plasma Ca2+ concentration - active form stimulated by PTH - production stimulated by low serum phosphate - opens "valves" from intestine, kidney, and bones to deposit Ca2+ in blood - calcitonin closes valves when levels get high enough and Ca2+ is deposited in bones Deficiency: Ricketts (children)- poor calcification of bones, bow-legged; osteomalacia (adults)- demineralization of skeleton Toxicity- anorexia, excessive thirst, vomiting, weight loss, hypercalcemia, Ca2+ deposition in soft tissues, atherosclerosis, cardiomyopathy Sources: fish oils, egg yolks, butter, milk, (NOT IN PLANTS), steroid prohormone formed in skin
65
``` Vitamin K (Active form, biological function, deficiency diseases, toxicity, sources) ```
Fat soluble Active form: K1 (phylloquinone), K2 (menaquinone), K3 (menadione) Biological function: gamma-carboxylation of glutamic acid (helps Ca2+ bind better), 4 blood clotting factors and osteocalcin for bone metabolism Deficiency: newborns are deficient b/c gut is sterile, bleeding (K3 causes RBC lysis) Toxicity: none Sources: green leafy veggies, intestinal bacteria, very little in breast milk, very little in liver
66
``` Vitamin E (Active form, biological function, deficiency diseases, toxicity, sources) ```
Fat soluble Active form: alpha-tocopherol (b/c of alpha-T binding protein) Biological function: antioxidant, prevents oxidation of PUFA in membrane Deficiency: reproductive failure, hemolytic anemia, muscular dystrophy, nerve damage Toxicity: high doses interfere w/ vit K metabolism Sources: vegetable oil, wheat germ, nuts, green leafy veggies
67
Vitamin C
Water soluble Active form: ascorbic acid Biological function: antioxidant (regenerate vit E, fight bacterial infection), hydroxylation (w/ Cu or Fe) for collagen biosynthesis, degradation of cholesterol, synthesis of biogenic amines Deficiency: Scurvy (swollen legs, loose teeth, bleeding gums, poor wound healing) Toxicity: none Sources: citrus fruits, potatoes Other: deficiency caused by poor nutrition, smoking, oral contraceptives, wound healing
68
Thiamin (B1) | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: thiamin pyrophosphate (TPP) Biological function: energy releasing, co-enzyme for pyruvate decarboxylase (TCA cycle), alpha-ketoglutarate (TCA cycle), transketolase (pentose-phosphate shunt) Deficiency: Beri beri (mental confusion, anorexia, muscle weakness, peripheral paralysis, edema, muscle-wasting, tachycardia, enlarged heart), Sudden Unexplained Nocturnal Death Toxicity: none Sources: whole grains, enriched flour, meat
69
Riboflavin (B2) | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD) Biological function: energy-releasing, coenzyme for ETC (oxphos), succinic dehydrogenase (TCA cycle), FA oxidation, AA oxidases, monoamine oxidase, xanthine oxidase, glutathione reductase Deficiency: glossitis (tongue), dermatitis, lesions of mouth, skin, scrotum, cheilosis (cracked lips), sebhorreic dermatitis (lesions of nasal-labial folds, eyelids, ears, vulva, anus, free border of prepuce) Toxicity: none Sources: milk, grain, meat, poultry, fish
70
Niacin (B3) | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: NAD+, NADPH Biological function: energy releasing, coenzyme in glycolysis, TCA cycle, FA synthesis and oxidation Deficiency: Pellagra (3Ds), mental changes (fatigue, insomnia, apathy, hallucination, confusion, loss of memory) Toxicity: none Sources: meat, poultry, fish, grain, can be produced from tryptophan
71
Biotin | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: biotin Biological function: energy releasing, carboxylation rxns- acetyl CoA carboxylase (FA synthesis), pyruvate carboxylase (oxaloacetate formation), propionyl CoA carboxylase (FA and AA metabolism), B-methylcrotonyl CoA carboxylase (Leu degradation) Deficiency: rarely, but can occur w/ large amounts of raw eggs (GASTON), pregnant women, infants, alcoholics, elderly, long-term antibiotics usage --> dry skin, dermatitis Toxicity: none Sources: liver, milk, egg yolk, synthesized by intestinal bacteria
72
``` Pantothenic acid (Active form, biological function, deficiency diseases, toxicity, sources) ```
Water soluble Active form: CoASH Biological function: energy releasing, part of CoA, involved in acylation rxns Deficiency: unlikely, but neuromotor disorders Toxicity: none Sources: whole grains, liver, kidney, egg yolk
73
``` Folic acid (Active form, biological function, deficiency diseases, toxicity, sources) ```
Water soluble Active form: tetrahydrofolic acid (THF) Biological function: hematopoetic, 1C metabolism in AA, purine, and thymine metabolism Deficiency: fetus development- spina bifida Toxicity: none Sources: liver, dark green leafy veggies, wheat germ, whole grains Other: deficiency can occur from B12 deficiency, pregnancy, alcoholics, drugs
74
B12 | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: cobalamin Biological function: hematopoetic, methionine synthetase, methylmalonyl CoA mutase Deficiency: megaloblastic anemia, pernicious anemia, nerve damage Toxicity: none Sources: liver, meat, eggs, sea food, made by intestinal bacteria, NOT IN PLANTS Other: deficiency can result from antibiotics
75
Pyridoxine (B6) | Active form, biological function, deficiency diseases, toxicity, sources
Water soluble Active form: pyridoxal phosphate Biological function: multiple effect, coenzyme (transamination, decarbosylation) Deficiency: dermatitis, cheilosis, glossitis, anemia, neurological changes Toxicity: nerve damage to arms and legs Sources: grains, meat, fish, fruits, veggies Other: deficiency from oral contraceptives, drugs, protein intake
76
Pyruvate | key junction: can produce...
``` Lactate Oxaloacetate Alanine G6P Acetyl CoA ```
77
Acetyl CoA | key junction: can produce...
Fatty Acids CO2 Cholesterol Ketone bodies
78
Glucose-6-Phosphate | key junction: can produce...
Glycogen Pyruvate Ribose-5-phosphate
79
Acute stress response
Catecholamines (epinephrine) * ** Muscle: increase glycolysis (but no TCA cycle), increase glycogenolysis, decrease glycogen synthesis, increase lipolysis - Liver: decrease glycolysis, increase glycogenolysis, decrease glycogen synthesis, increase gluconeogenesis, decrease FA synthesis - Adipose: increase lipolysis
80
Long-term stress response
Glucocorticoids (cortisol) - Muscle: increase protein degradation to produce AAs * ** Liver: gluconeogenesis (w/ AAs and glycerol), increase glycogen sythesis - Adipose: increase lipolysis
81
Fed state | What happens to carbs? proteins? fats?
Carbs: insulin stimulates uptake of glucose by muscle and fat, promotes glycogen storage in liver and fat Proteins: insulin stimulates AA uptake and protein synthesis in liver and muscle Fats: insulin stimulates storage of fats as triglycerols by stimulating synthesis of VLDL in liver (carried to fat tissues)
82
Fasting state
1. Glycogenolysis (liver): stimulated by glucagon --> increases [cAMP] --> stimulates PKA --> activates phosphorylase kinase (inhibits glycogen synthase) --> converts glycogen phosphorylase b to a --> degrades glycogen to G1P --> G6P --> glucose 12-30 hours 2. Gluconeogenesis: requires lactate (anaerobic resp in muscle and RBC), glycerol (lipolysis in adipose tissue, activated by glucagon), AAs (muscle breakdown) 3. FFA converted to acetyl CoA via B-ox --> converted to ketone bodies that can be used later in brain
83
Starvation
Triacylglycerols become primary fuel 1. Ketone bodies used in brain as fuel after 3-5 days 2. Gluconeogenesis by liver slows so AAs and proteins are spared 3. Blood glucose maintained around 65 mg/dL for 50-60 days, while adipose stores are depleted and muscle is used 4. Death from cardiomyopathy/muscle weakness, NOT hypoglycemia

Foundations 1 (8 decks)

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