• Created by: H.O.C.
  • Created on: 24-03-21 16:04

What are carbohydrates?

- Carbohydrates are one of 4 main organic compounds which are found in all living organisms

  • 'Organic' means they contain carbon 

- Monosaccharides = single molecules of sugars composed of Carbon, Hydrogen, and Oxygen with the general formula: (CH2O)n, meaning the number of carbon/oxygen is the same but the number of hydrogen is double the number of carbon/oxygen - e.g. C6H12O6 (glucose)

- Monosaccharides bond to each other to form disaccharides which bond to each other to form oligosaccharides and then polysaccharides 

  •  Monosaccharides with 3 carbon = Triose, 4 carbons = Tetrose, 5 carbons = pentose, 6 carbons = hexose
  • Disaccharides are formed when 2 monosaccharides bond to each other, oligosaccharides is when 3-10 monosaccharides bond together, and polysaccharides is more than 10 bonded together

- The monosaccharides forming the carbohydrate polymers is Glucose 

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- Monosaccharides are single molecules of sugars composed of Carbon, Hydrogen, and Oxygen 

- Glucose is the monosaccharide which bonds together to form carbohydrate polysaccharides 

- Glucose has 2 isomers: Alpha-Glucose and Beta-Glucose

  • Isomers mean they have the same chemical make-up but different structures 
  • Alpha-glucose has the first carbon bonded to Hydrogen at the top and a Hydroxyl group at the bottom, Beta-glucose has the first carbon bonded the other way around - OH top, H bottom

What is alpha glucose? - Quora

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- Disaccharides are formed when two monosaccharides bond together in a condensation reaction

  • A condensation reaction is where water is lost
  • When two molecules of monosaccharides need to bond, a molecule of water needs to be released to make space for the bond.
  • Thus a Hydrogen atom and a Hydroxyl group from each molecule bond to make water 

- 2 alpha-glucose = maltose

Sugar Subunits | BioNinja

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- Polysaccharides are formed when 10 or more monosaccharides bond together in a condensation reaction to form a long chain of a polysaccharide

  • This chain is either a straight line or a coilied helix shape depending on isomer of glucose

- Alpha-glucose monosaccharides create a coiled helix shaped amylase polysaccharide

- Beta-glucose monosaccharides create a straight line of cellulose

  • Beta-glucose create a straight line because every other monomer of glucose needs to be flipped around in order for 2 Hydroxyl groups to line up and bond - it's the remaining oxygen of one of the hydroxyl groups that creates the glycosidic bonds 
  • The fact that cellulose polysaccharides are straight means they are able to be parallel to one another.
  • This results in the hydroxyl groups in the monosaccharides to be in close proximity and forming hydrogen bonds because of the polar nature of the hydroxyl group. The numerous hydrogen bonds throughout the parallel lines makes cellulose strong.
  • The lines bond to other lines and form microfibrils which bond to each other to form macrofibrils of cellulose which wrap around plant cells in different directions
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Types of monosaccharides

- Single molecules of sugars include:

  • Glucose (hexose)
  • Fructose (hexose)
  • Galactose (hexose)
  • Ribose (pentose)
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Types of disaccharides

- 2 alpha-glucose monosacc. = 1 maltose disaccharide

  • In germinating seeds, complex carbs, starch, is broken down into maltose disaccharides to provide energy for the plant to grow

- 1 alpha-glucose + 1 fructose monosacc. = 1 sucrose disaccharide

  • Glucose and fructose made during photosynthesis creates sucrose which can be transported around plants in the phloem vessels 

- 1 alpha-glucose + 1 galactose monosacc. = 1 lactose disaccahride

  • Lactose is in the breast milk of mammilian mothers to provide energy to their offsprings

Monosaccharides and disaccharides are both sugars as they are sweet, polysaccharides are not.  

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Types of polysaccharides

- Polysaccharides are made from many simple sugar monosaccharides bonded to each other in glycosidic bonds, formed by condensation reactions

- Alpha-glucose monosaccharides = amylose polysaccharide

- Beta-glucose monosaccharides = cellulose polysaccharide 

  • Amylose and cellulose are glucose molecules bonded to each other in 1,4 glycosidic bonds (carbon number 1 and carbon number 2 bonded together)
  • Amylose is able to arrange itself in different ways. It can connect to the sides of a coil of amylose in a 1,6 glycosidic.

- An amylose polysacc. with 1,4 bonds + some amylose polysacc by 1,6 bonds = amylopectin

- Amylose + amylopectin = starch

- An amylose polysacc. with 1,4 bonds + many amylose by 1,6 bonds = glycogen 

- A cellulose polysacc. + an acetyl amine group = chitin

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