BCH Exam 3/Final

• glycogen

  • storage form of glucose in animals
  • readily mobilized - stores a lot of potential energy
  • formation is dependent on concentration of glucose in blood
  • alpha 1,4 glycosidic bonds and alpha 1,6 glycosidic bonds every 10 units
• slow twitch muscles


  aerobic respiration and high cytochrome concentration (where brown color comes from)

  not a lot of glycolysis or glycogen
• fast twitch muscles


  involved in fermentation and glycolysis

  not as many mitochondria and need a lot of glycogen
• glycogen granules


  electron dense and found in cytosol

  glycogen is scattered in liver and provide for the rest of the body
• liver


  involved in controlled glucose release to maintain glucose concentration in blood
• glycogen breakdown

  1. release of glucose from chains (as glucose 1 phosphate)
  2. transfer branches onto chains
  3. hydrolyze alpha 1,6 glucosidic bonds
• glycogen phosphorylase


  release glucose from glycogen chain by adding phosphate

  steps when 4 residues remain before the branch

  release glucose as glucose 1 phosphate (cannot be transported out of cell)
• transferase


  transfers 3 residues of glycogen to another straight chain of glycogen

  allows branched residue to be removed
• alpha 1,6 glycosidase


  hydrolyzes the branched residue at the alpha 1,6 glycosidic bond
• transferase and alpha 1,6 glycosidase are a bifunctional enzyme - found in one protein and has two separate active sites
• glucose-1-phosphate keeps glucose inside the cells (no transporters)
• epinephrine


  fight-or-flight response hormone released by adrenal medula

  signals to make glucose from glycogen due to receptor binding on LIVER

  activates PKA by making cAMP and freeing catalytic site to make active enzyme
• glucagon


  hormone released when glucose concentration in blood is low
• glycogen synthase


  can add glucose to chain only if 4 or more residues are present

  need primer of glucose - glycogenin
• glycogenin


  dimeric enzyme that auto-glycosylates and starts glycogen chain

  8-residue oliogsaccharide/dimer
• triacylglycerol


  highly concentrated energy storage with glycerol backbone

  usually made of different fatty acids (saturated or unsaturated)

  reduced or anhydrous
• bile salts


  synthesized from cholesterol in liver

  stored and secreted by gallbladder (glycocholate)
• chylomicrons


  vary in size and is mostly composed of triacylglycerides

  surrounded by phospholipid membrane with cholesterol

  surface is largely hydrophilic and allows for ball to be soluble
• fat droplets


  TAG storage in adipose cells

  long-term energy storage; store more potential energy than glycogen in carbs
• acetyl CoA carboxylase stimulation

  insulin and citrate
• acetyl CoA carboxylase inhibition


  AMP (low E charge), glucagon, epinephrine, and palmitoyl
• citrate partially activates inactive carboxylase (formation of enzyme filaments); low level activation and causes conformational change
• palmitoyl CoA


  depolymerizes acetyl CoA carboxylase filaments

  16C FA (feedback inhibition) - too much product

  turn off partially active enzyme (inhibits citrate translocase)
• malonyl CoA


  inhibits carnitine acyltransferase I

  blocks entry of FA into mitochondria
• prostaglandins


  stimulate inflammation, modulate synaptic transmission, control ion transport across membranes, regulate blood flow
• acetylsalicylate (asprin)


  reversible inhibitor prostaglandin synthase
• 2 sources of amino acids

  intracellular protein turnover

  dietary protein intake
• intracellular protein turnover (making and destroying proteins)


  not folder/mis-folded, denatured, oxidized

  encoded in amino acid sequence (N-rule) - how long a protein is supposed to live
• all proteins start with methionine and it is removed to expose different amino acid in posttranslational modification
• proteins are tagged with ubiquitin (4 chain) for degradation
• ubiquitin


  small soluble protein that is covalently attached to epsilon-NH groups on Lys of target protein
• urea cycle defects


  no alternative pathway - all leads to hyperammonemia

  leads to brain damage

  treatments aim to circumvent metabolic block

  excrete argininosuccinate instead
• maple syrup urine diease


  defective oxidative carboxylation of branched amino acids

  mental and physical retardation
• phenylketonuria (PKU)


  defect phenylalanine hydroxylase

  Phe accumulates in all body fluids

  severe mental retardation
• glutamate synthesis


  where ammonia is the N nucleophile; Schiff base is reduced by hydride reaction using NADPH followed by protonatio
• NADH or NADPH acts as a biological hydride reducing agent


  can reduce an aldehyde or ketone

  in Glu synthesis it reduces an imine to an amine
• synthetic families


  groups of amino acids derived from the same molecule
• nonessential amino acids


  human beings can biosynthesize these

  syntheses are simple
• essential amino acids


  human beings cannot synthesize these

  syntheses are complex (must be consumed)
• PLP


  transamination reactions are catalyzed by PLP-dependent enzymes