Biochemistry Dr.Guy's

  1. What is vitamin B1? Coenzyme? Functions?
    Thiamine, Thiamine pyrophosphate (TPP), oxidative decarboxylations (decarboxylase enzymes), carbohydrate metabolism (We need TPP to convert pyruvate to acetyl-CoA
  2. What is unique about vit. B1? What will a deficiency cause?
    contains sulfer, Beri-berij (dry, wet, infantile --> numbness of the fingers and toes), Wernicke-Korsakoff's (in alcoholics)
  3. What is unique about vit. B2? What is its name? Coenzyme?
    contains the isoalloxazine ring system (flavin ring - 3 ring system), riboflavin, flavin mononucleotide (FMN), Flavin adenine dinucleotide (FAD)
  4. What are the functions of vit. B2?
    Oxidative reduction reactions (dehydrogenase enzymes) (note: Lose Electrons Oxidation, Gain Electrons Reduction), aids succinic dehydrogenase in the conversion of succinic acid to fumaric acid
  5. What does vit. B2 do with the electrons it accepts? What will a defiency cause? Excess?
    brings them to the electron transport chain to make 2 ATP, chelosis (lips crack), yellow urine (excess)
  6. What is vit B3? What can we make it from? Coenzymes?
    Niacin, half from tryptophan (essential AA), Nicotinamide adenine dinucleotide (NAD), Nicotinamide adenine dinucleotide phosphate (NADP)
  7. What is NAD involved in?
    vasodilator (large amounts), hypocholesterolemic effect, most important conezyme because it is involved in catabolism
  8. What is NADP involved in?
    anabolism, such as fatty acid synthesis
  9. Functions of vit. B3? Deficiency?
    oxidation-reduction reactions (dehydrogenase enzymes), takes electrons to the electron transport chain for 3 ATP, deficiency causes pellagra (Dermatitis, diarrhea, dementia and Death) (also can be from a tryptophan deficiency)
  10. What is vit. B5? What is unique about it? Coenzyme? Function?
    Pantothenic acid (pantothenate) contains sulfur, Coenzyme A, CoASH, forms a thioester bond (high energy), activating molecules, acyl group transfer
  11. What is vit. B6? What is unique about it? Coenzyme? What causes deficiency?
    pyridoxine, specializes in protein metabolism, trans am has a B6 engine, pyridoxal phosphate, pyridoxamine phosphate, oral contraceptives cause deficiency
  12. What are the functions of vit. B6?
    • transaminase (amino acids --> alpha keto acids)
    • Tryptophan --> niacin
    • Alanine --> Pyruvate
    • Glutamate --> Alpha ketoglutarate
    • Aspartate --> oxaloacetate
  13. What is vit. B9? Coenzymes? What vitamins are needed for the formation of THF?
    Folic acid, tetrahydrofolate (THF)/FH4/pteryglutamic acid, vitamin C and NADP
  14. Functions of vit. B9? Deficiency diseases?
    aids in the formation of purines and pyrimidines (RNA and DNA), maturation of RBCs, one carbon transfer, tropical sprue, meagloblastic anemia (masks a B12 anemia), pregnant women
  15. What is vit. B12? Coenzymes? Where is it found? What is unique about it?
    cyanocobalamine, 5-deoxyadenosyl cobolamine, neither animals or plants can make B12, it is made by micro-organisms and found in animal products (vegetarians must supplement), contains a metal trace element (cobalt)
  16. What are the functions of vit. B12?
    formation and maturation of RBCs, hep form the porphyrin ring of hemoglobin (Hb), B12 and folic acid are needed for methyl group synthesis (isomeriztion of methyl malonyl), CoA to succinyl CoA, transfer and metabolism, without B12 we develop a fatty liver
  17. What causes deficiency of B12?
    most due to lack of intrinsic factor which is secreted by the parietal (oxytinic) cells of the stomach, IF binds to B12 and carries it to the distal ileum where it is absorbed into the blood stream, strict vegetarians, elderly (lack of IF) and people with GI problems
  18. What occurs with vit. B12 deficiency?
    megaloblastic anemia (B9 or B12) --> pernicious anemia (B12 only)
  19. What is biotin? Where is it made? Functions? What interfers with absorption?
    vitamin and coenzyme, 1/2 is made in the GI tract, carboxylation reactions (carboxylase enzymes, transfer of CO2) ex. synthesis of lipids (acetyl-CoA to malonyl CoA) and Pyruvate --> oxaloacetate, avidin (raw eggs) interferes with absorption
  20. What is vit. C? Who can make it? Deficiency?
    ascorbic acid, some animals and plants can make vit. C from glucose, humans lack the enzyme, deficiency will cause scurvy
  21. Functions of vit. C?
    • hydroxylation reactions (hydroxylase enzymes, transfer OH group)
    • Cholesterol to bile acids (hypocholesterolemic effect)
    • helps make steroids in the adrenal cortex
    • synthesis of collagen and elastin
    • helps abosorb iron in the GI tract
    • Helps convert folic acid to FH4
    • preservative - antioxidant of CYTOPLASM
  22. What vitamins are fat soluble (in order of depletion)?
    KDEA (we have longest storage time for vitamin A, shortest for vitamin K)
  23. What is a monosaccharide?
    single sugar unit, may be a polyhyroxy aldehyde (aldose - carbonyl group is at the end such as glucose) or a polyhydrosy ketone (ketose - carbonyl group is not at the end such as fructose)
  24. What are the two ring forms that sugars may take?
    pyranose (six-membered, most stable, ex. glucose) and furanose (five-membered, ex. fructose)
  25. How much of our energy stores are carbohydrates?
    only a small amount, most is stored as triglycerides because it is more effiecient
  26. Name monosaccharides based on number of carbons.
    triose is 3, tetrose is 4, pentose is 5, hexose is 6, heptose is 7
  27. What is glyceraldehyde?
    aldotriose, reference compound, if OH is on the right then it is D-glyceraldehyde, if OH is on the left it is L-glyceraldehyde
  28. What is ribose?
    aldopentose, part of RNA and DNA
  29. Three important aldohexoses?
    glucose, mannose, galactose
  30. What is Dihydroxyacetone?
    ketotriose, only sugar without a chiral carbon
  31. two ketopentoses?
    ribulose and xyulose
  32. What is fructose?
  33. What is the reducing power of sugars?
    has the ability to donate hydrogens, carbonyl group does this, it is also know as the "Free anomeric carbon", sucrose is the only exception (does not have reducing power)
  34. What is maltose?
    glucose + glucose in an alpha1-4 link
  35. What is isomaltose?
    glucose + glucose in an alpha 1-6-O-glycosidic bond
  36. What is lactose?
    milk sugar, glucose + galactose
  37. What is sucrose?
    glucose + fructose
  38. What is cellobiose?
    hemicellulose, glucose + glucose in beta links
  39. What are the three most common polysaccharides?
    cellulose, starch and glycogen, contain 100 to 1000s of monosaccharides
  40. What is cellulose?
    most abundant polysaccharide (undigestable)
  41. What is starch?
    storage form of glucose in plants, two types are amylose (straight chain, alpha 1-4 links only) and amylopectin (80%, branches, alpha 1-4 and alpha 1-6 links)
  42. What is glycogen?
    animal storage form of glucose, it is like amylopectin but more highly branched (more condensed)
  43. What are mucopolysaccharides?
    protective polysaccharides found in connective tissue - chiton (skin of insects), hyaluronic acid (lubricates joints), chondroitin sulfate (bones and joints), heparin (anticoagulant in liver), glycosaminoglycans
  44. What part of carbohydrate digestion occurs in the mouth?
    salivary alpha amylase (ptylain, secreted by salivary glands) - hydrolyzes many of the alpha1-4 glycosidic links of starch
  45. What part of carbohydrate digestion occurs in the small intestine?
    pancreatic alpha amylase works on any alpha 1-4 bonds missed by salivary amylase, it will NOT work on beta 1-4 links as found in cellulose
  46. What are the products of amylase?
    glucose, maltose, isomaltose
  47. What carbohydrate digestion occurs in the intestinal mucosa?
    disaccharides are broken down as part of "intestinal juice" and carbs are absorbed as monosaccharides, monosaccharides in food do not need to be hydrolyzed prior to absorption
  48. What are the catabolic pathways of carbohydrate metabolism?
    glycolysis and glycogenolysis
  49. What are the anabolic pathways?
    gluconeogenesis and glycogenesis
  50. What pathways lower blood sugar levels?
    those activated by insulin and inhibited by glucagon and cortisol --> glycolysis (breakdown of glucose) and glycogenesis (synthesis of glycogen)
  51. What pathways raise blood sugar?
    those activated by glucagon and cortisol and inhibited by insulin --> gluconeogensis (synthesis of glucose) and glycogenolysis (breakdown of glycogen)
  52. What does glycogenesis do?
    remove glucose from the blood, convert it to UDP-glucose then add it to the glycogen chain
  53. What does glycogen synthase do? When is it active?
    adds glucose to glycogen, synthase a (active) is present under control of insulin, synthase b (inactive) is present under the control of glucagon and epinephrine
  54. What does glycogenolysis do?
    remove glucose from glycogen and put it in the blood via glycogen phsphorylase - phosphorylase b (inactive) is present under the control of insulin, phosphorylase a (active) is present under the control of glucagon and epinephrine
  55. How do glucagon/epinephrine release glucose?
    bind to adenylate cyclase which converts ATP to cAMP which activates phosphorylase and deactivates synthase
  56. How do the glucagon and epinephrine pathways differ?
    epinephrine --> glucose stays in the cell, glucagon --> glucose leaves the cell to raise blood glucose
  57. What is anaerobic glycolysis?
    does not use oxygen, breaks down glucose to 2 lactate and 2 ATP, occurs in cytoplasm
  58. What is aerobic glycolysis?
    usese oxygen and mitochondria to yield 36 ATP per glucose
  59. What are the rate limiting enzymes of glycolysis?
    • hexokinase (muslce)/glucokinase (liver)
    • phosphofructokinase
    • pyruvate kinase
    • all allosteric enzymes
    • all participate in a reaction that produces glucose
  60. What activates the rate limiting enzymes?
    insulin, high levels of ADP
  61. What inhibits the rate limiting enzymes?
    glucagon and high levels of ATP
  62. What are the steps of glycolysis?
    Image Upload 1
  63. What happens to pyruvate?
    converted to acetyl-CoA and enters Kreb cycle or lactate dehydrogenase converts it to lactate, using one NADH
  64. What enzymes are used in place of the rate limiting enzymes of glycolysis in gluconeogenesis?
    • Pyruvate carboxylase, PEP carboxykinase --> pyruvate kinase
    • Fructose 1,6 diphosphatase --> phosphofructokinase
    • Glucose 6 phosphatase --> hexokinase/glucokinase
  65. What activates the enzymes of gluconeogenesis?
    cortisol and glucagon
  66. Where does the TCA (kreb, citric acid) cycle take place? What reaction is required for it to start?
    mitochondria, pyruvate must be converted to acetyl-CoA, NADH, FADH2 and CO2 first (requires NAD, FAD, Mg+, TPP, lipoic acid, CoA and biotin, pyruvate dehydrogenase)
  67. What 4 things can happen to pyruvate?
    • Decarboxylation --> acetyl-CoA
    • Reduction --> lactic acid
    • Carboxylation --> oxaloacetate
    • Transamination --> alanine
  68. What yields acetyl-CoA? What can acetyl-CoA become?
    pyruvate, AAs, Fatty acids --> acetyl-CoA --> fatty acids, cholesterol, ketone bodies, TCA cycle
  69. TCA cycle
    • Image Upload 2
    • Can I Keep Selling Sex For Money Officer?
  70. What are the total energy yields from glycolysis and TCA cycle per molecule of glucose?
    • Glycolysis: 2 NADH + 2 ATP = 8 ATP
    • PDH complex: 2 NADH = 6 ATP
    • TCA cycle: 6 NADH + 2 FADH2 + 2 GTP = 24 ATP
    • Total: 38 ATP
  71. What is the pentose phosphate pathway?
    hexose monophosphate pathway - does NOT make ATP, located in the cytoplasm, anaerobic, provides NADPH for fat and steroid synthesis, provides ribose for nucleic acid synthesis, allows for the interconversion of sugars
  72. Where does the electron go in the electron transport chain?
    NADH --> FAD --> FADH2 --> ubiquinone (Coenzyme Q10) --> cytochrome B --> C1 --> C --> A --> oxidase --> A3 --> O2 --> H2O
  73. What steps yield ATP? What steps require Cu2+/Fe2+? What is the final electron acceptor?
    • NADH --> FAD, B --> C1, A --> oxidase
    • A --> oxidase --> A3
    • O2 is the final electron acceptor, yielding water
  74. What is an uncoupler?
    substances that uncouple the electron cascade, ex. dinitrophenol --> diminishes the electron transport chain significantly
  75. What is the connection between electron transport chain and increased thyroid hormone?
    thyrotoxicosis --> electron transport chain will yield heat but no ATP
  76. What is saponification? What lipids are saponifiable?
    hydrolysis of a lipid in the presences of alkaline metal hydroxide, any lipid containing fatty acids
  77. What lipids are non-saponifiiable?
    Do NOT contain fatty acids - vitamins ADEK, cholesterol, steroids, prostagladins
  78. What are saturated fatty acids?
    no double bonds, animal fat, palmitic acid (16 carbons), stearic acid (18 carbons)
  79. What are unsaturated fatty acids?
    one or more double bonds, vegetable fat, double bonds are CIS, essential fatty acids are all unsaturated
  80. What are the essential fatty acids?
    • linoleic - 18 carbons, 2 double bonds (between carbons 9 and 10 and 12 and 13, octadecadienoic (omega 6) - essential because our body cannot make a double bond between 12 and 13
    • Linolenic - 18 carbons, 3 double bonds, octadecatrienoic (omega 3)
    • Arachadonic - 20 carbons, 4 double bonds, eicosatetrenoic (omega 6) - prostagladins are made from
  81. What are triglycerides?
    depot fat (fatty acids are not stored), stored in adipocytes, NOT found in membranes (other lipids are)
  82. What are phospholipids?
    phosphoglycerol (PL) used for structure (cell membrane)
  83. What are the three different forms of vitamin A?
    retinal (aldehyde, most active), retinol (alcohol), retinoic acid (maintain growth)
  84. What are the functions of vitamin A?
    vision is #1 (rhodopsin - purple pigment found in the rods of the retina, regenerate when you sleep), opsin and all trans retinal (converted to 11-cis-retinal which becomes rhodopsin), growth (regenerate bone), mucous (IgA), maintains keratinized tissues
  85. What are the symptoms of vitamin A deficiency?
    Xeropthalmia (young, dry eyes --> blindness) and nyctalopia (adult, night blindness, dark spots on liver)
  86. What are the forms of vitamin D?
    • cholecalciferol (D3) - animal form (inactive)
    • ergocalciferol (D2) - plant form (inactive)
    • 7-dehydrocholesterol --UV light--> cholicalciferol (skin) --25-hydroxylase--> 25-hydroxycholecalciferol --1-hydroxylase--> 1,25-dihydroxycholecalciferol (active form)
  87. What is the most important enzyme (control point) in activation of vitamin D? What hormone will promote the activation of vitamin D?
    1-hydroxylase, PTH
  88. What are the functions of vitamin D?
    steroid hormone with 3 target sites: intestines (increases calcium binding/absorption), bone (takes calcium and PO4 from bone and puts it in the blood, PTH also elevates blood calcium levels), kidney (increases reabsorption of calcium and PO4 in renal tubule)
  89. What is the relationship between calcium and PO4?
    inverse relationship (when one increases body will work to decrease the other)
  90. What does a deficiency of vitamin D caused by? What does it cause?
    Steatorrhea (fatty stool) will prevent absorption of vitamin D --> rickets, osteomalacia, osteoporosis (don't absorb calcium), pigeon breast, bow leg, knock knees
  91. What is vitamin E? What are its functions?
    Tocopherol (vegetable oil, wheat germ), antioxidant, protects the carbon double bonds in cell membranes from oxidants (free radicals), protects the fatty acid chains in the vegetable oil that we eat
  92. What are the main antioxidants?
    Vitamins ACE and selinium (cannot function without vitamin E though)
  93. What will a deficiency in vitamin E cause?
    hemolytic anemia - premature infant with immature RBC, cell membranes are susceptible to free radicals, vitamin E therapy is given to premature infants to prevent this
  94. What are the forms of vitamin K? Where is it from?
    phyloquinone, menaquinone, menadione, microorganisms in our large intestine make 1/2 of our vitamin K, the rest we get from large green leafy vegetables
  95. What will a deficiency of vitamin K be caused by?
    infants may have deficiency because their intestinal flora are not yet developed, adults only become deficient if they have obstructive jaundice, antibiotics or sulfur drugs, patients with steatorrhea
  96. What are the functions of vitamin K?
    coagulation: produces Prothrombin (II), stuart factor (IX), christmas factor (X), VII
  97. What is the sphincter of oddi?
    opens into the descending portion of the duodenum
  98. What is the hepatopancreatic ampulla?
    ampulla of vater - joining of the common bile duct and the pancreatic duct before enetering the duodenum
  99. What does secretin do?
    acid chyme from the stomach will activate specific cells in the duodenum to produce secretin which will travel to the exocrine pancreas which secretes bicarbonate ions into the duodenum, raising the pH to 7-8 so proper lipid digestion can occur
  100. What is cholecystokinin?
    pancreozymin - stimulates gall bladder to release bile into the duodenum (emulsifies lipids), stimulate pancreas to release zymogens for protein digestion, presence of fat in chyme will activate cells in duodenum to produce cholecystokinin
  101. What does bile do?
    made in liver, concentrated in gallbladder - emulsifies lipids in the duodenum which increases the surface area and forms mixed micelles
  102. What is a mixed micelle?
    NOT a lipoprotein! It is made from lipids and bile salts, it does NOT have a protein coat
  103. What is pancreatic lipase?
    enzyme made in pancreas which hydrolizes triglycerides into fatty acids and monoglycerol in the duodenum
  104. What occurs after fatty acids and monoglycerols enter the intestinal epithelium?
    they recombine to form triglycerides again which aggregate with phospholipids and cholesterol and are coated with protein to form chylomicrons
  105. What are chylomicrons?
    lipoprotein, formed in the intestinal mucosa
  106. How are chylomicrons absorbed?
    enter the lacteal of a villus, transported via lymph to the thoracic duct to the left subclavian vein then arrive at liver through the hepatic artery where they are broken down by lipoprotein lipase into free fatty acids and glycerol which enter liver cells and recombine into triglycerides
  107. how are lipids transported through the body?
    • insoluble in water, must be transported attached to protein
    • chylomicron - carries exogenous triglycerides from diet, made in the intestinal mucosa
    • VLDL - carries endogenous triglycerides made in the liver and some free cholesterol
    • LDL - carries mainly cholesterol esters
    • HDL - carries mainly protein and phospholipids
  108. Where does fatty acid oxidation occur? What are the products?
    mitochondria (fatty acid synthesis occured in cytoplasm) --> acetyl CoA, FADH2, NADH
  109. How are fatty acids activated?
    By acyl CoA synthetase (adds a CoA and ATP) - converts fatty acid to fatty acyl-CoA which can be moved into the mitochondria by carnitine (note: lysine is the precursor to carnitine)
  110. What are the steps of beta oxidation?
    • dehydrogenation - FADH2 is formed
    • hydration
    • dehydrogenation - NADH is formed
    • thiolytic cleavage - produces Acetyl-CoA and fatty acid which is 2 carbons shorter than the original, steps are repeated until only acetyl-CoA is left
  111. How many FADH2, NADH and acetyl-CoA are formed by beta oxidation?
    • Acetyl-CoA = # of carbons/2
    • FADH2 = NADH = # of acetyl-CoA - 1
  112. What is ketogenesis?
    ketone bodies are made from excess acetyl-CoA in the liver from incomplete oxidation of fatty acids
  113. What are the ketone bodies? Where are they used?
    acetone, acetoacetate (acetoacetic acid - 2 acetyl units), beta hydroxybutarate (3 acetyl units) - acetoacetate and beta hydroxybutarate are metabolized in muscle and heart, acetone is excreted through the lungs
  114. What is ketoacidosis?
    too many ketones in the blood --> low pH --> coma and death
  115. What conditions can cause ketoacidosis?
    diabetic (can't use insulin, all energy must come from fat --> excess acetyl-CoA is converted to ketones) and fasting (body breaks down fat stores)
  116. Where does acetyl-CoA come from for fatty acid synthesis?
    acetyl-CoA is shuttled from the mitochondria to the cytosol via citrate
  117. What are the building blocks of fatty acids?
    malonyl-CoA (acetyl CoA carboxylase converts acetyl-CoA with the help of biotin)
  118. How are fatty acids synthesized?
    acetyl-CoA (first 2 carbons) and malonyl-CoA are combined giving CO2 and a 4 carbon unit --> reduction using NADPH, dehydration and another reduction using NADPH creates a 4 carbon fatty acid, malonyl-CoA groups continue to be added until you have enough carbons
  119. Where is cholesterol made? From what?
    cytoplasm, acetyl-CoA --> Hydroxyl methylgluteral CoA (HMG) (regulator) --> mevalonate --> squalene
  120. Basic structure of an amino acid.
    Image Upload 3
  121. How are proteins made?
    amino acids are linked together by peptide bonds
  122. What is unique about glycine?
    it is the only amino acid without a chiral carbon (it is optically inactive), hydrogen side chain, important in the formation of collagen and elastin, makes purine rings and porphyrin ring of heme
  123. Why do amino acids make good buffers?
    they are amphoteric - can act as an acid (proton donor) or a base (proton acceptor), most are in their zwitterion form at neutral pH (have both a + and - charge)
  124. Alanine
    methyl side chain, can be transaminated to pyruvate
  125. What are the branched chain AAs?
    Leucine, valine, isoleucine
  126. What AAs are purely ketogenic?
    leucine and lysine
  127. Which AAs are both ketogenic and glucogenic?
    isoleucine, phenylalanine, threonine, tryptophan, and tyrosine
  128. What is unique about proline?
    interupts alpha helix, ring attaches to amino group
  129. What do we make from tryptophan?
    1/2 of our niacin (B3) and serotonin
  130. What happens to phenylalanine?
    Phe --> Tyr --> L-dopa --> dopamine --> norepinephrine --> epinephrine
  131. What is PKU?
    Phenylketonuria - Phe cannot be converted to Tyr so Phe builds up in the brain and causes irreversible damage, must restrict Phe intake from diet
  132. What is unique about methionine?
    thioester side chain, contains sulfur, homocysteine is a product of demethylation of methionine, limiting AA in legumes
  133. What is unique about serine?
    active center of enzymes, binds trace elements
  134. What is unique about threonine?
    alcohol in the side chain
  135. What is unique about cysteine?
    thiol (sulfur) side chain, two can join via disulfide bond to make cystine
  136. What amino acids are acidic?
    Aspartic acid (aspartate) and glutamic acid (glutamate) - the inhibitory neurotransmitter, GABA is made from the decarboxylation of glutamic acid
  137. What amino acids are basic?
    histidine, arginine (urea cycle, spermatogenesis and DNA formation), lysine (precursor to carnitine)
  138. What AAs are aromatic?
    phenylalanine, tyrosine, tryptophan
  139. What AAs contain alcohol (hydroxyl group)?
    serine and threonine
  140. What are the non-standard amino acids?
    hydroxyproline (collagen and elastin), hydroxylysine (collagen), ornithine and citrulline (urea cycle)
  141. What are the essential AAs?
    VAL MET LEU and took a TRP to an ILE but because of HIS LYS she had to pay THR PHE
  142. What is the primary structure of an AA?
    linear AA sequence, polypeptide (long AA chain)
  143. What is the secondary structure of an AA?
    Alpha helix, beta sheet (for strength and rigidity) - recurring arrangement held together by hydrogen bonds
  144. What is the tertiary structure of an AA?
    bending and folding of a chain upon itself --> globular
  145. What is the quatenary structure of an AA?
    aggregation of two or more polypeptide chains bound by strong non-covalent bonds
  146. What are some fibrous proteins?
    collagen, elastin, alpha keratin
  147. What is collagen?
    33% glycine, hydroxyproline, hydroxylysine (proline and lysine are hydroxylated by vitamin C after they are incoporated in the polypeptide) --> without vitamin C we will not form collagen
  148. What is elastin?
    stretchy - ligaments, skin, blood vessels - 33% glycine, proline (some hydroxyproline - still need vitamin C), NO hydroxylysine
  149. What is alpha keratin?
    strongest protein in the body, found in hair and nails, when steam heat hair it breaks the intrachain H-bonds but not the disulfide bonds so alpha keratin --> beta keratin (straight)
  150. What are bases are in RNA? DNA?
    DNA has Adenine, Guanine, Thymine, and Cytosine, RNA has Adenine, Guanine, Uracil, Cytosine
  151. What is a nucleoside composed of?
    base (purine or pyrimidine) and sugar (deoxyribose and ribose)
  152. What is a nucleotide composed of?
    base, sugar and phosphate
  153. What forms can adenine take?
    Adenosine (ribonucleoside), Adenylate (AMP, ribonucleotide)
  154. Which bases are purines?
    Adenine, Guanine (You become PURe with AGe)
  155. Which bases are pyrimidines?
    Cytosine, Uracil, Thymine (you CUT PYRIMIDS)
  156. What is B9 needed for?
    the synthesis of purines and pyrimidines
  157. What bonds link DNA and RNA?
    3,5 phosphodiester bonds between phosphate and sugar (between adjacent nucleotides in the same chain), hydrogen bonds between bases (between chains)
  158. What is replication?
    DNA --> DNA
  159. What is transcription?
    DNA --> RNA
  160. What is translation?
    RNA --> protein
  161. What is a ribosome?
    the cellular organelle consisting of 2 subunits, on which mRNA are translated into proteins (the factory for building proteins)
  162. What is mRNA?
    RNA molecule transcribed from a complementary DNA strand which is able to be translated in the ribosome (blueprints for the building of a protein)
  163. What is tRNA?
    small RNA molecule that brings the appropriate amino acid to the ribosome (the truck that brings the material)
  164. What is a codon? anticodon?
    codon is a sequence of 3 nucleotides in an mRNA molecule specifying an AA. An anticodon is 3 bases in a tRNA molecule that are complementary to 3 bases of a specific codon in mRNA
  165. How much plasma proteins are in the blood? Where are they made?
    6 to 8 mg of proteins/100mL of blood (note: all of these are made in the liver except gamma globulins which are made in the blood)
  166. What is albumin?
    most abundant plasma protein (55%), globular, contributes 80% of the osmotic pressure in the capillaries
  167. What are gamma globulins?
    immunoglobulins (antibodies), 11% of plasma proteins, 5 families - IgG, IgA, IgM, IgE, IgD, production is stimulated by antigens
  168. What are enzymes?
    all enzymes are proteins (but not all proteins are enzymes), they act as biocatalysts, increase the rate of reaction by decreasing the energy of activation
  169. What is a cofactor?
    required for the activation of an enzyme, may be mineral (inorganic - Ca, K, Cu, Zn, Mn, Mo) or conezymes (organic - derived from B vitamins)
  170. What is the michaelis-menton constant?
    Km = the concentration of a specific substrate at which a given enzyme yields 1/2 of its maximum velocity, lower Km indicates higher attraction of enzyme to substrate (faster reaction)
  171. What are the major classes of enzymes?
    oxidoreductase, transferase, hydrolase, lyase, ligase, isomerase
  172. What are oxidoreductases?
    catalyze oxidation-reduction reactions - LEO the lion says GER - ex. dehydrogenases - have NAD, FAD, FMN or NADP as their active center
  173. What are transferases?
    catalyze reactions where a group is transferred - ex. aminotransferases (transaminases - catalyze reactions in which an amino group is transferred, must have B6), kinases (catalyze reaction in which a phosphate is transferred), transcarboxylases (catalyze a reaction in which CO2 is transferred)
  174. What are the 2 most common transport proteins?
    myoglobin (one chain, one oxygen) and hemoglobin (4 chains, 4 oxygen)
  175. What is the structure of hemoglobin?
    2 alpha subunits and 2 beta subunits, each with a heme group which each contain an iron which can bind one oxygen
  176. What are the forms of iron?
    ferrous (Fe2+ - absorbed and carried in hemoglobin), ferritin (Fe3+ - storage form, "store in a tin"), transferrin (Fe3+ - blood transport)
  177. What is cooperativity?
    once the initial oxygen binds to hemoglobin it becomes easier for the 2nd, 3rd and 4th to bind
  178. Where is the affinity of Hb for oxygen high and low?
    low in the tissue because low partial pressure of oxygen, high in the lungs where partial pressure of oxygen is high
  179. What is the bohr effect?
    a high pH will cause a shift to the left (Hb will have a higher affinity for oxygen at a given partial pressure), a low pH will cause a shift to the right (Hb will have a lower affinity for oxygen at each partial pressure)
  180. What is gastrin?
    stimulated by the presence of food in your stomach or distention of the stomach (stomach movement), produced at the antrum by the enteroendocrine cells, gastrin stimulates the chief cells of the stomach to produce pepsinogen (zymogen)
  181. What activates pepsinogen?
    HCl then it activates itself
  182. What is cholecystokinin?
    pancreozymin - stimulates gall bladder to release bile and the exocrine pancreas to release zymogens into the small intestine (trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B)
  183. What activates the zymogens?
    proteolytic enzymes (split off AAs), trypsinogen is activated by enterokinase to become trypsin, trypsin then activates the other zymogens
  184. What do transaminases do?
    transfer a nitrogen from an AA to an alpha keto acid to make an AA or to be converted to UREA for excretion, these enzymes are used to moniter liver disease in the blood GOT or GPT, liver converts toxic ammonia to non-toxic urea which is excreted by kidneys in urine
  185. Urea cycle
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Biochemistry Dr.Guy's
Flashcards based on Dr.Guy's board review