Lipids

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Lipids

• By a fat guy

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Function of Lipids

• Cell membrane structure
• Creates a barrier for the cells
• Controls flow of materials
• Energy Storage
• Fats are stored in adipose tissue
• Hormones and Vitamins
• Hormones communication between cells
• Vitamins assist in the regulation of biological
  processes

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Types of Lipids

• Fatty Acids
• Saturated
• Unsaturated
• Glycerides
• Mono, Di, Tri
• Phosphoglycerides
• Complex Lipids
• Lipoproteins
• Glycolipids
• Steriods Waxes

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Fatty Acid Structures

• Two different structures
• Saturated
• No double bonds
• Unsaturated
• One or more double bonds

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Saturated Fats

• Properties
• Often solid at room temperature
• Contain only single C-C bonds
• Closely packed with strong attraction between
  chains
• High melting point
• Examples
• Lard
• Baking grease

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Unsaturated Fatty Acids

• Properties
• Contain one or more double CC bonds
• Nonlinear chains do not allow molecules to pack
  closely
• Few interactions between chains
• Low melting points
• Liquid at room temperature
• Examples
• Monounsaturated
• Olive, peanut, and canola oils
• Polyunsaturated
• Vegetable oils, chicken, fish, vegetables,
  avocados

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Hydrogenation

• Unsaturated fatty acids can also go through a
  process called hydrogenation. Hydrogenation is
  the process of converting double bonds in oils to
  single bonds. The solid products are used to
  make margarine and other hydrogenated items.
• Unsaturated compounds react with Hv2
• Ni or Pt catalyst
• CC bonds ? C-C bonds

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Glycerides

• Definition- a lipid which consists of a glycerol
  molecule with one , two, or three fatty acids
  attached to it.
• These different types are called monoglycerides,
  diglycerides, triglycerides respectively.
• Fat storage molecules
• side note glycerol-def- the special alcohol
  that forms the backbone of a triglyceride.
• Triglyceride is a regular fat or oil molecule.

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Monoglycerides

• These lipids are also known as monoacylglycerols
• They are fatty acid monoesters of glycerols.
• Due to this, two isomeric forms exist.

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Monoglycerides (cont)

• Monoglycerides are found in very low amounts in
  cell extracts but are intermediates in the
  degradation of diglycerides and triglycerides.
• They are the most polar components of simple
  lipids.
• One hydrocarbon chain and two alcohol groups
• They have detergent properties, therefore
  producing micelles in water solutions

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Diglycerides

• These lipids are also known as diacylglycerols
• Made of two fatty acids attached to a glycerol
  molecule.
• Diglycerides are generated mainly during
  digestion in the stomach and the duodenal part of
  the intestine
• In cell bio, diglycerides are generated from
  phospholipids
• In lipid extracts, diglycerides are always
  present
• In cell extracts, the molecules are generally two
  different fatty acid chains
• Diglycerides are important intermediates in the
  biosynthesis of triglycerides and phospholipids,
  and play a fundamental role in the cellular
  signalling.

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Diglycerides (cont)

• Diglycerides also occur in two isometric forms

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Triglycerides

• These lipids are also known as triacylglycerols
• Made of three fatty acids attached to a glycerol
  molecule
• They are the most abundant dietary lipids (mono
  and di make up lt1)
• They are the form in which we store reduced
  carbon for energy.
• Triglycerides have a chemical structure shaped
  like an E

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Phosphoglycerides

• Phosphoglycerides are lipids that contain a
  phosphate group.
• Uses are production of cell membranes, and
  emulsifying agents.

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Complex Lipids

• Lipids bound to other molecules
• Combination results in a structure
• Four major classes of plasma lipoproteins
• Chylomicrons
• Very-low density lipoproteins (VLDL)
• Low-density lipoproteins (LDL)
• High-density lipoproteins (HDL)

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Function of Lipoproteins

• Chylomicrons- transport triglycerides from
  intestine to other tissues except kidneys.
• VLDL- bind triglycerides in liver and carry them
  to fat tissue
• LDL- carry cholesterol to peripheral tissues
• HDL- bound to plasma cholesterol. Transport
  cholesterol to liver

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Nonglycerides

• Sphingolipids- a type of phospholipid not derived
  from fat. Used primarily in nerve tissue-myelin
  sheathe. In people, 25 of all lipids are
  sphingolipids.
• Steroids- broad class of compounds that all have
  the same base structure. Examples of steroids
  cortisone and cholesterol
• Cholesterol- the principal membrane lipid for
  fluidity.
• Waxes- water insoluble and hard to hydrolyze.
  Often used for a protective coating (leaves,
  skin, fur, etc). Ester of a fatty acid and a
  long chain of alcohol.

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Steroid Structures
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Digestion of Lipids
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Phospholipid Bilayer

• a two-layered arrangement of phosphate and lipid
  molecules that form a cell membrane, the
  hydrophobic lipid ends facing inward and the
  hydrophilic phosphate ends facing outward. Also
  called lipid bilayer.
• Phospholipids contain glycerol, two fatty acids,
  and a phosphate group. The phosphate group is
  polar (hydrophilic), enabling it to interact with
  water. The fatty acid tails are nonpolar
  (hydrophobic) and do not interact with water.