Lipids

• Lipids are organic compounds formed mainly from alcohol and fatty acids combined together by ester linkage
• Lipids - Insoluble in water, but soluble in fat or organic solvents (ether, chloroform, benzene, acetone).
• Lipids - Includes fats, oils, waxes and related compounds
• Lipids - Widely distributed in nature, both in plants and in animals
• Lipids are hydrophobic, nonpolar molecules.

  SOLUBLE in nonpolar solvents.

  INSOLUBLE in polar solvents, such as water.
• IMPORTANCE OF LIPIDS PART 1

  1. Fats and oils are the principal stored forms of energy in many organisms.
  2. More palatable and storable to unlimited amount compare to Carbohydrates.
  3. They have a high-energy value (25% of body needs) and they provide more energy per gram than carbohydrates and proteins.
• IMPORTANCE OF LIPIDS PART 2

  1. Lipids are important in biological systems because they form the cell membrane.
  2. Several essential vitamins are lipids (Vitamins A,D,E,K)
  3. Lipoproteins, which are complex of lipids and proteins, are important cellular constituents that present both in the cellular and subcellular membranes. So when cholesterol enters in the membrane structure and is used for the synthesis of adrenal cortical hormones, vit D3 and bile acids.
• Other lipids, although present in relatively small quantities, play crucial roles as:

  1. Enzyme cofactors
  2. Electron carriers
  3. Hydrophobic anchors for proteins
  4. “Chaperones” to help membrane proteins fold
  5. Emulsifying agents in the digestive tract
  6. Hormones
• LIPIDS: Fill in the Blank

  A) Fatty Acids

  B) Triglycerides

  C) Waxes

  D) Plasmalogens

  E) Sphingolipids

  F) Glycosphingolipids

  G) Cerebrosides

  H) Phosphatidates

  I) Phosphatidylcholines

  J) Gangliosides

  K) Phosphatidylethanolamines

  
• A fatty acid is a molecule characterized by the presence of a carboxylic acid group attached to a long hydrocarbon chain.
• Fatty acids come in two major varieties:

  1. Saturated
  2. Unsaturated
• The melting point of a fatty acid is influenced by the number of double bonds that the molecule contains and by the length of the hydrocarbon tail.
• Fatty Acids

  • The melting point decreases as the number of double bonds increases
  • As the length of the hydrocarbon tail increases, the melting point increases.
• Saturated Fatty Acids

  • does not have any double bonds
  • A fatty acid is saturated when every carbon atom in the hydrocarbon chain is bonded to as many hydrogen atoms as possible
  • FATS are solids at room temperature
• Unsaturated Fatty Acids

  • An unsaturated fatty acid can have one or more double bonds along its hydrocarbon chain
  • OILS are liquids at room temperature
• Identify the picture:

  A) Saturated Fatty Acid

  
• Identify the picture:

  A) Unsaturated Fatty Acid

  
• Fill in the Blanks

  A) Palmitoleic

  B) Oleic

  C) Linoleic

  D) Linolenic

  E) Arachidonic

  F) 16

  G) 18

  H) 18

  I) 18

  J) 20

  
• Fill in the Blanks

  A) Lauric

  B) Myristic

  C) Palmitic

  D) Stearic

  E) Arachidic

  F) Lignoceric

  G) 12

  H) 14

  I) 16

  J) 18

  K) 20

  L) 24

  
• Omega Fatty Acids - Unsaturated fatty acids can also be classified according to the location of the closest double bond to the methyl end of the carbon chain.
• • Palmitoleic acid is an omega-7 fatty acid.
  • Oleic acid is an omega-9 fatty acid.
  • Linoleic acid is an omega-6 fatty acid.
  • Linolenic acid is an omega-3 fatty acid.
• Identify the ff.

  A) Eicosapentaenoic

  B) Docosahexaenoic

  
• PHYSICAL PROPERTIES OF FATS AND OILS

  • Freshly prepared fats and oils:

  – Colorless

  – Odorless

  – Tasteless
• ESSENTIAL AND NON-ESSENTIAL FATTY ACIDS

  • Essential Fatty Acid - cannot be synthesized in the body and can only be obtained from the diet.
  • Non-essential Fatty Acid - can be made by the human body and do not need to be obtained from diet alone.
• CLASSIFICATION OF LIPIDS

  1. Simple or Homolipids
  2. Compound or Heterolipids
  3. Derived
• Simple Lipids Examples:

  • Fats and Oils
  • Waxes
• Fats and Oils - These are ester of fatty acids with trihydroxy alcohol: glycerol.
• Waxes - Esters of fatty acids with high molecular weight monohydroxy alcohols.
• Compound Lipids Examples:

  • Phospholipids
  • Glycolipids
  • Lipoproteins
  • Sulfo-lipids
  • amino lipids
• Derived Lipids - These include fatty acids, alcohols, mono- and diglycerides, steroids, terpenes and carotenoids.
• TRIGLYCERIDES - The simplest lipids constructed from fatty acids are the triacylglycerols, also referred to as triglycerides, fats, or neutral fats. (TAG)
• Triacylglycerols are composed of three fatty acids each in ester linkage with a single glycerol.
• Mixed triglycerides – different type of fatty acids connected to glycerol (e.g., stearo-diolein and palmito-oleo-stearin)
• Natural fats are mixtures of mixed triglycerides with a small amount of simple TAG
• Common fatty acids in animal fats are palmitic, stearic and oleic acids.
• Form a separate phase of microscopic, oily droplets in the aqueous cytosol, serving as depots of metabolic fuel
• Most natural fats, such as those in vegetable oils, dairy products, and animal fat, are complex mixtures of triacylglycerols. These contain a variety of fatty acids differing in chain length and degree of saturation.
• Waxes are esters of long-chain (C-14 to C-36) saturated and unsaturated fatty acids with long-chain (C-16 to C-30) alcohols.
• Their melting points (60 to 100°C) are generally higher than those of triacylglycerols.
• • Waxes serve as energy store and water repellents
  • Waxes also serve a diversity of other functions related to their water-repellent properties and their firm consistency.