carbohydrates-monosaccarides and disaccharides

• A condensation​ reaction between two monomers e.g monosaccharides forms a molecule called a disaccharide  ,through the formation of a glycosidic bond, and a molecule of water is eliminated.  If these condensation reactions continue to occur, then a long chain called a polysaccharide will form which is held together by multiple glycosidic bonds​
• Which 3 elements make up a carbohydrate?

  Carbon, hydrogen and oxygen​
• Why are carbohydrates an important food group?

  They should be your body's main source of energy
• Give some examples of carbohydrates. Can you describe their functions/importance?​

  Glucose, starch, sucrose, cellulose
• where n is the number of carbons in the molecule. ​

  ​

  Therefore, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules.

  
• what is this

  A) glucose

  
• formula for glucose

   C₆H₁₂O₆
• what is this

  A) alpha glucose

  
• what is this

  A) beta glucose

  
• Two monosaccharides can be joined together to make a disaccharide. A disaccharide is made up of 2 sugars​
• • Maltose is a disaccharide formed from two glucose monomers​​
  • Sucrose is a disaccharide formed from a glucose monomer and a fructose monomer​
  • Lactose is a disaccharide formed from a glucose monomer and a galactose monomer​
• monomer small units from which larger molecules are made​Monomers are usually made from carbon​

  They can join together in long chains to forms polymers​
• • Hydrolysis reactions break chemical bonds using water ​
  • ​This can split a polymer into its component parts
• • Polysaccharides are long chains of many monosaccharides joined together by glycosidic bonds. ​
  • There are three important polysaccharides:​

  1. Starch​
  2. Glycogen​
  3. Cellulose​
• Polysaccharides-Starch​

  • Used by plants as an energy store​- can by hydrolysed when needed and used for respiration​
  • Compact​-a lot can be stored in a small space​
  • Large​-does not diffuse out of cells​
  • Insoluble​-doesn’t affect water potential so water is not drawn in by osmosis​
  • Branched​-greater area for enzymes to act on so hydrolysis can happen rapidly​
• • Starch is a polymer of alpha glucose​
  • it is a mixture of two polymers: amylose and amylopectin.​
  • Amylose make up of around 20-30% of the total starch.​
  • Amylose is a linear polysaccharide consisting of long chains of glucose molecules bound together via alpha 1-4 glycosidic linkages.​
• Amylose

  • The long chain of amylose can fold onto itself .​
  • When the chain of amylose folds onto itself, a spiral-shaped structure is formed known as a helix. ​
  • The helix is kept in shape by the hydrogen bonds between the hydrogen atoms and the hydroxyl groups of glucose molecules. ​
• • Amylopectin is a branched-chain polysaccharide composed of glucose units linked primarily by α-1,4-glycosidic bonds but with occasional α-1,6-glycosidic bonds, which are responsible for the branching.​
• • Glycogen is the energy reserve carbohydrate of animals. ​
  • Practically all mammalian cells contain some stored carbohydrates in the form of glycogen, but it is especially abundant in the liver (4%–8% by weight of tissue) and in skeletal muscle cells (0.5%–1.0%). ​
  • Like starch in plants, glycogen is found as granules in liver and muscle cells.​
• • Glycogen is structurally quite similar to amylopectin.​
  • The α-glucose monomers are joined together via condensation reactions and are held in place by 1,4 and 1,6-glycosidic bonds. ​
  • Glycogen is more highly branched than amylopectin and the branches are shorter. ​
• • The fact that glycogen is a highly branched molecule means it has a larger surface area for enzymes to attach to. ​
  • This means that it is readily broken down back into glucose when cells are running low on glucose. ​
  • The glucose can be broken down to release energy.​
• • Like amylose, cellulose is a linear polymer of glucose. ​
  • It differs, however, in that the glucose units are joined by β-1,4-glycosidic linkages.​
  • All the glucose molecules in cellulose are in beta orientation meaning that the OH groups of the carbon number 1 are oriented upwards. 
• cellulose

  • When 2 molecules of β  glucose line up to form glycosidic bonds , the OH group on carbon atom 1 can only line up along side the hydroxyl group of carbon atom 4 if one of the molecule is rotated at 180 to the other.​
  • The OH group on carbon atom 1 projects above the ring and the hydroxyl group on carbon atom 4 projects below the ring. ​