• energy balance- ingested energy equals energy needs of body (can't create or destroy energy)
• translation: you need to maintain your current weight

• ingest energy less than energy needs
• translation: you will lose weight (wasting state)
  • breakdown functional tissue (muscle)

• ingested energy more than energy needs of body
• translation- you will gain weight (adipose cells have no limit to how much fat they can store)

• energy needed in a state of inactivity
  • how we measure nitrogen balance
• average = 24 kcal/kg of body wt/24 hrs

1. fats broken down by lipases into fatty acids
2. go into enterocyte as micelle
3. tag with cholesterol, phospholipids to form chylomicron
4. enters into lymphatic system

1. broken down by proteases to AA's
2. enter enterocyte via transporters
3. exit via transporter into portal circulation

1. broken down into dissacharides by alpha amylase: maltose, isomaltase
2. broken down by brush border glycosidases in small intestines into:
   1. glucose
   2. galactos
   3. fructose
3. enter enterocyte via transporters
4. enter portal circulation

1. preproinsulin form at first
2. pre signal carries peptide to ER membrane
3. translation continues, and signal sequence (pre) is clipped off
4. proinsulin stored in granules
5. proinsulin granules activated via proteolysis
   1. Ser proteases break broteins in two separate locations
6. produces C peptide and insulin WITHIN vesicles
7. when three molecules of insulin come together and form a hexemer with zinc, you have functional insulin

1. GLUT2 picks up increased glucose concentration from the blood
2. glucokinase phosphorylates glucose (make G6P)
3. runs through glycolysis and other metabolic processes
4. this leads to metabolite that stimulates the release of calcium into the cytosol
5. promotes movement of vesicles to membrane and to be exocytosed
6. insulin released into blood

1. sensed by receptors in plasma membrane
2. insulin bind to alpha receptors, leading to confirmation change in beta subunits of the receptor
3. these receptors have Tyr kinase activity, and insulin leads to autophosphorylation of Tyr residues
4. leads to series of metabolic events that dephosphorylates proteins

1. pancreas sense low blood sugar
2. bind to plasma receptors in liver and adipose
3. works via trimeric G protein
   1. dissociation of protein into alpha-GTP and beta-gamma
   2. activates adenyle cyclase
   3. increases cAMP
   4. activates PKA (cleave off catalytic subunit)
   5. phosphorylate various enzymes

1. glucose go down conc. gradient into liver
2. glucose phosphorylated by glucokinase (high concetration of glucose activate GK) form G6P (glucose is trapped)
3. ATP will allosterically regulate PFK and PK
4. from G6P, undergo glycogenesis to create glycogen
   1. in conditions of increased size of glycogen, could also be converted to fatty acids

• glucose polymer
• alpha 1,4 and alpha 1,6 glycosidic bonds
• synthesized bound to glycogenin
  • has enzymatic activity (phosphorylate Tyr) and put glucoses onto it (about 8 glucose monomers)

1. glycogenin has enzymatic activity (phosphorylate Tyr) and put glucoses onto it (about 8 glucose monomers)
2. add glucose to non-reducing ends

1. G6P converted to G1P via mutase
2. G1P uses UTP to converted to UDP-glucose and pyrophosphate via pyrophosphorylase
3. UDP-glucose combine with primer (piece of glycogen) to form UDP and glycogen with a glucose on non reducing end via glycogen synthetase
   1. if the linear chain becomes to long, branching enzyme will move the glucose and make alpha 1,6 links

• via glycogen synthase (phosphorylated via PKA)
  • inactive in phosphorylated form
  • active in dephosphorylated form
  • allosteric modulation- can be activated via binding of G6P in spite of if the enzyme is phosphorylated

muscle

liver

epinepherine

norepinepherine

1. 7 acetyl CoA, CO2 and ATP form malonyl CoA and ADP via acetyl-CoA carboxylase (coenzyme: biotin)
   1. rate limiting step
2. 7 malonyl CoA, acetyl CoA, and 14 NADPH form palmitate, 14 NADP and 8 CoA via fatty acid synthase

• inactive in phosphorylated form
• positive allosteric modulator: citrate

• dimer made of two identical subunits
• each subunit contains many domains (each domain is an enzyme)
• each chain running in opposite directions head to tail

1. acetyl CoA added to KS domain via ACP
2. swing to MAT bound acetate added to malonyl group bound to ACP via carboxylation to produce beta keto fatty acyl ACP (C4)
3. beta keto fatty acyl ACP swings to KS domain (reductase) where reduced by NADPH
4. beta hydroxy fattay acyl CP swing to DH where we remove water producing enoyl ACP
5. enoyl-ACP swing to ER domain (reductase) where it is reduced by NADPH the product is C4 fatty acyl CoA
6. repeat seven times
7. when it reaches C16, complex hydrolyzed by thioesterase domain