macro carbs

• Carbohydrates


  • Commonly called sugars; Energy source
  • Polar and water soluble
  • Variety of cellular functions, including energy storage and structure
  • Stoichiometric formula: (CH2O)n ; where n is the number of carbon atoms in the molecule
  • Ratio of C to H to O = 1:2:1 in carbohydrate molecules

  
• Carbohydrate subtypes


  • Monosaccharides
  • Disaccharides
  • Polysaccharides

  
• Monosaccharides


  • Sugar polymers / building blocks of sugar
  • React with other monosaccharides to form disaccharides, oligosaccharides, and polysaccharides
  • No. of carbon atoms, usually 3-7
  • Most mono s. names end w/ suffix 'ose'

  
• Monosaccharides


  • Glucose (blood sugar)
  • Fructose (fruit sugar)
  • Galactose (milk sugar)

  
• Monosaccharides


  • Depending on the number of C, there may be triose (3 C), pentoses (5 C), hexoses (6 C)
  • If the sugar structure has an aldehyde gp. attached to it (fxnal gp. w/ structure R-CHO), it is an aldose
  • If it has a ketone gp (RC(O)=R'), it is a ketose
  • Aldoses have a carbonyl gp at the end of the carbon chain
  • Ketoses have a carbonyl gp at the middle of the carbon chain

  
• Glucose, Galactose, and Fructose are all hexoses

  
• Monosaccharides


  • Can exist as linear chain or as ring-shaped molecules
  • Structural isomers −same chemical formula but different arrangement of atoms
  • Glucose and Galactose are aldoses; Fructose is a ketose
  • In aqueous solutions, they are usually found in ring forms

  
• Isomers


  Molecules with the same chemical formula but with atoms of different arrangements, shape, or orientation/structure
• Types of Isomers


  • Structural Isomers
  • Stereoisomers

  
• Disaccharide


  • Monosaccharides undergo a dehydration reaction
  • Hydroxyl group of one monosaccharide combines with the hydrogen of the other monosaccharides, releasing water, forming a covalent bond
  • Known as a glycosidic bond
  • Glycosidic bonds can be alpha or beta type
  • Joining 2 mono s. together (glucose + fructose) yields formation of disaccharide, sucrose (table sugar)
  • An alpha-glycosidic bond forms when both carbons have same stereochemistry; Beta-glycosidic bond occurs when the two carbons have different stereochemistry

  
• Common Disaccharides


  • Lactose = glucose + galactose monomers
  • Maltose = glucose + glucose
  • Sucrose = glucose + fructose

  
• Polysaccharides


  • Made up monosaccharides (polymers)
  • Contain repeating units of glucose
  • Long chain monosaccharides linked by glycosidic bonds
  • For energy storage and structural molecules
  • Chain maybe branched/unbranched

  
• Important Polysaccharides


  • Starch
  • Glycogen
  • Cellulose
  • Chitin

  
• Starch


  • Made by plants as stored energy
  • In plants, excess glucose is stored as starch in different plant parts including roots and seeds
  • When starch is consumed, it is broken down by enzymes (salivary amylase) into smaller molecules (maltose, glucose)
  • Humans make similar molecules of stored energy in a form of glycogen

  
• Glycogen


  • Stored form of glucose in humans and other vertebrates
  • Animal equivalent of starch is highly branched molecule usually stored in liver and muscle cells
  • Broken down to release glucose via glycogenolysis

  
• Cellulose


  • Provides scaffolding and holds up plants
  • Water insoluble and indigestible to animals
  • The way glucose subunits are joined, every monomer is flipped relative to the next, resulting in linear, fibrous structure
  • Beta 1-4 linkage cannot be broken down by human digestive enzymes
  • Cellulases breakdown cellulose into glucose monomers that can be used as energy source

  
• Oligosaccharides


  • Commonly composed of 2-10 monosaccharides
  • Often found in the surface of cell membranes and functions in cell-cell recognition and signaling
  • Glycoproteins and Glycolipids

  
• Blood Type


  Type O has the least saccharide containing blood type on the surface of its RBCs; while AB has the most