L4 | LIPIDS

• LIPIDS

  • Group of hydrophobic molecules that play an important role in living organisms ; hydrocarbons
  • Hydrophobic
  • Hydro - water
  • Phobic - fear of
• LIPIDS

  • Soluble in organic solvent
  • Insoluble in polar solvent (e.g. Water)
• PRIMARY FUNCTIONS

  • Energy Storage
  • Protection
  • Insulation
  • Lubrication
  • Hormone precursor
  • Key component of cell membrane
• LIPIDS

  1. TRIGLYCERIDE
  2. PHOSPHOLIPIDS
  3. STEROIDS
  4. WAXES
• FATS

  • solid at room temperature
  • used by animals for insulation, protection, and energy storage
• OILS

  • liquid at room temperature 
  • used by plants for energy storage
• TRIGLYCERIDE

  • Contain two types of subunit molecules: glycerol and fatty acids
• SUBUNIT MOLECULES

  A) GLYCEROL

  B) FATTY ACIDS

  
• FATTY ACIDS

  • Has 3 main parts:
  • Acid group
  • Hydrocarbon chain
  • Methyl group
• FATTY ACIDS

  A) ACID GROUP

  B) HYDROCARBON CHAIN

  C) METHYL GROUP

  
• SATURATED FATTY ACIDS

  • only single carbon to carbon bonds
  • animal fats
  • High shelf life
  • solid

  
• UNSATURATED FATTY ACIDS

  • one to several double bonds 
  • Liquid 
  • Low shelf life 
  • TRANS FAT: has opposite hydrogen atoms
  • Vegetable oils 
• TO BECOME A TRIGLYCERIDE

  • 3 separate fatty acids have to bond with a glycerol molecule through the process of dehydration synthesis
• PHOSPHOLIPIDS

  • similar to triglyceride; contain a glycerol and two fatty acids (nonpolar)
  • difference: a phosphate group (polar) rather than a third fatty acid is attached to the third carbon of glycerol
• PHOSPHOLIPIDS

  • form cell membranes, creating a barrier that regulates entry and exit of substances
  • form micelles or membranes in water
  • Head - polar; hydrophilic
  • Tail - nonpolar; hydrophobic
  • tend to arrange themselves so that only the hydrophilic heads interact with a watery environment and hydrophobic tails crowd inward away from water
• PHOSPHOLIPIDS STRUCTURE

  A) HYDROPHILIC HEAD

  B) HYDROPHOBIC TAIL

  
• STEROIDS

  • Composed of 4 fused rings of carbon (different functional groups are attached)
  • well-known steroid molecule: cholesterol
  • the precursor for the synthesis of other steroids (such as testosterone, estrogen, vitamin D, cortisone)
  • present in plasma membranes where it stabilizes the membrane 
  • maintains cell membrane fluidity 
  • essential for cell integrity 
• WAXES

  • nonpolar and repel water
  • found in protective coatings on leaves and on outer surfaces of animals
  • produced in the ear of some animals to protect the eardrum
• CLASSIFICATION OF LIPIDS

  1. SIMPLE LIPID
  2. COMPLEX LIPID
  3. DERIVED LIPID
• SIMPLE LIPID

  • esters of fatty acids with various alcohols
• TYPE OF ALCOHOL THESE ARE SUBCLASSIFIED AS: (SIMPLE LIPID)

  1. NEUTRAL FATS OR OILS
  2. WAXES
• NEUTRAL FATS OR OILS

  • Alcohol is GLYCEROL
  • esters of fatty acids  with alcohol 
  • Uncharged
• WAXES

  • Alcohol is  other than glycerol
  • esters of fatty acids with higher molecular weight monohydric alcohols
• COMPLEX LIPID

  • esters of fatty acids with alcohol containing additional prosthetic groups.
• SUBCLASSIFIED ACCORDING TO THE TYPE OF PROSTHETIC GROUPS (COMPLEX LIPID):

  1. PHOSPHOLIPIDS
  2. GLYCOLIPIDS
  3. LIPOPROTEINS
• PHOSPHOLIPIDS

  • FA + ALCOHOL + PHOSPHORIC ACID
  • frequently have nitrogen containing bases
  • may be classified on the basis of the type of alcohol present:
  • GLYCEROPHOSPHOLIPIDS
  • SPHINGOPHOSPHOLIPIDS
• GLYCEROPHOSPHOLIPIDS

  • ALCOHOL IS GLYCEROL
• SPHINGOPHOSPHOLIPIDS

  • ALCOHOL IS SPHINGOSINE
• GLYCOLIPIDS

  • FA + ALCOHOL [SPHINGOSINE] + CARBOHYDRATE WITH NITROGEN BASE
  • do not contain phosphate group
• LIPOPROTEINS

  • Lipid with prosthetic group protein
• DERIVED LIPID

  • derivatives obtained on the hydrolysis of group 1 and group 2 lipids which possess the characteristics of lipids. 
• FATTY ACIDS

  • naturally occurring carboxylic acids with an unbranched carbon chain and an even number of carbon atoms.
  • the pathway by which fatty acids are biosynthesized they almost always contain an even number of carbon atom
• LONG CHAIN FATTY ACIDS

  • 12 to 26 carbon atoms
  • found in meats and fish
• MEDIUM CHAIN FATTY ACIDS

  • 6 to 10 carbon atoms
• SHORT CHAIN FATTY ACIDS

  • Fewer than 6 carbon atoms
• ESSENTIAL FATTY ACIDS

  • Essential means you NEED to get them from the diet because the body cannot manufacture them.
• FUNCTION OF ESSENTIAL FATTY ACIDS

  • required for the membrane structure and function
  • Transport of cholesterol
  • Formation of lipoproteins
  • Prevention of fatty liver
  • Needed for the synthesis of another important group of compounds, namely eicosa
• ESSENTIAL FATTY ACIDS:

  1. ΑLPHA - LINOLENIC ACID
  2. LINOLEIC ACID
• ΑLPHA-LINOLENIC ACID

  • an omega-3 fatty acid
• LINOLEIC ACID

  • an omega-6 fatty acid found abundantly in soy oil, sunflower seeds,pumpkin seeds, sesame seeds, corn oil, and in most nuts