biochem

• Lipid


  Also known as fats, composed of mostly carbon-hydrogen bonds, rich source of energy, efficient way of storing excess calories
• Lipid


  Play an integral part of the cell membrane of human cells (bilipid layer)
• 1 g carbohydrates = 4 calories, 1 gram protein = 4 calories, 1 gram fat = 9 calories, 1 g of alcohol = 7 grams
• Fatty acids


  Linear chain of C-H bonds (hydrocarbon) that terminate with carboxylic acid group
• Fatty acids


  Only few exist as free (unbound) fatty acids, most are bound to albumin to interact with water (since fatty acids are hydrophobic)
• Fatty acids


  1. Released and transported through with serum albumin

  2. Some are found as part of triglycerides and phospholipids

  3. Esterified with the glycerol backbone of triglycerides (3 fatty acids) and phospholipids (2 fatty acids with phosphate group bind)
• Fatty acids


  Good source of energy, can be made to become acetyl-coenzyme A to make ATP
• Classification of fatty acids based on length

  • Short chain (4-6 C)
  • Medium chain (8-12 C)
  • Long chain (>12 C)
• Classification of fatty acids based on number of C=C double bonds

  • Saturated - if the FA has no double bond
  • Monounsaturated - isang DB
  • Polysaturated - more than one DB
• Cis forms of unsaturated fatty acids

  H atoms near the double bonds are on the same side of the chain, kinky chains (pa "V" ang structure), liquid - oil vegetable, usually from plants
• Trans forms of unsaturated fatty acids

  Hydrogen atoms are on the opposite sides of the chain, straight chains, solid if compact, found in animal fats
• Cis fats are beneficial and can promote good cholesterol, trans fats are considered harmful to Cardiovascular health especially those trans fats which come from unnatural resources (eg. hydrogenated oils in processed foods)
• Hydrogenation


  Usually commercial food establishments get cis forms of fats then convert it to trans fat
• Triglycerides


  Has glycerol backbone esterified with 3 fatty acids, each of the fatty acid can be potentially be different thus forming many possible structural forms, triglycerides that contain saturated fatty acids pack more closely and tend to be solid at room temperature - animal sources, most triglycerides from plant sources such as corn, sunflower seeds, etc. are rich in polyunsaturated fatty acids in cis forms - oil, hydrophobic - non polar charges, neutral lipid, good energy source kasi it has 3 fatty acids, large lipid but light, 80% of the fats in the diet
• Phospholipid


  Same structure as TAG except that the only have two esterified fatty acids, Amphipathic (hydrophobic fatty acids and hydrophilic phosphate head), not purely hydrophobic, glycerol backbone with 2 fatty acid and 1 phosphate group on 3rd carbon, Phosphate head groups can be choline, inositol, serine and ethanolamine, most of the time, one of the fatty acids is saturated while the other one is unsaturated
• Cholesterol


  Composed of 4 fused hydrophobic rings (A, B, C, D) called per-hydro-cyclo-pentano-phenan-threne ring and 1 hydrophilic hydroxyl group (-OH) attached to the A ring, Amphipathic, Hydroxyl groups are oriented outwards while the fused rings are buried in the cell membrane, exclusively synthesized by animals (humans), readily catabolized by cells thus does not serve as source of energy
• Bile production


  Cholesterol is converted to cholic and chenodeoxycholic acids (these are 2 components of the bile) which aids in fat digestion, the liver convert cholesterol to bile
• Steroid hormones


  Some cholesterol are used for steroid hormones, Testes will CORner the OVARY (testosterone, aldosterone, cortisol, androgens, estrogens and progesterones)
• Cholesteryl ester


  Same structure as cholesterol except that the hydroxyl group is replaced by fatty acid, hydrophobic, good source of energy because of the fatty acid
• Types of lipids


  • Triglycerides
  • Phospholipids
  • Cholesteryl ester
  • Cholesterol
• Majority of the lipids are hydrophobic, plasma is composed of 90%
• Lipoproteins


  Composed of lipids and proteins (apolipoproteins), main purpose is to transport energy, the core of lipoprotein essentially represents the cargo transported by lipoproteins, size correlates with its lipids content - higher, large lipoproteins have large core regions - TAG and CE, the larger the lipoprotein, the higher the lipid content than proteins, the lighter it is
• Apolipoproteins


  Protein portion of lipoproteins, found on the surface of the lipoproteins, help maintain the integrity of the lipoprotein, some bind to host cell receptors, some are activators or inhibitors, associates with the lipids because of their amphipathic helix (protein sequences that fold once in contact with a polar/non-polar interface)