Summary of Textbook Section 5.2

Assignment:
Write a summary of 5.2

Section 5.2: Carbohydrates provide fuel and building material

defining key terms

• carbohydrate - "organic compound made of sugar molecules" (Campbell, 820)
• monosaccharide - "sugar containing one sugar unit" (Campbell, 827)
• disaccharide - "sugar containing two monosaccharides" (Campbell, 822)
• polysaccharide - "long polymer chain made up of simple sugar monomers" (Campbell, 829)
• starch - "polysacchardie in plant cells that consists entirely of glucose monomers" (Campbell, 830)
• glycogen - "polysaccharide in animal cells that consists of many glucose monomers" (Campbell, 824)
• cellulose - "polysaccharide consisting of glucose monomers that reinforces plant-cell walls" (Campbell, 821)

Sugars (page 95,96)

• contain elements C, H, and O
• ratio of 1C 2H and 1O
• basic formula: CH2O
• most natural sugar molecules ring-shaped

image of glucose (taken from http://www.crsbooks.net/appendix.html on Sep. 1)

Monosaccharides

• one sugar unit
• common e.g. glucose, fructose, and galactose
• (esp. glucose) "the main fuel supply for cellular work" (Campbell, 95)
• cells extract stored energy from breaking down the molecules
• carbon skeletons of monosaccharides used as "raw material for manufacturing other kinds of organic molecules" (Campbell, 95)
• when not put to use, made into larger carbohydrates or make fat

image of sucrose (taken from http://www.unisanet.unisa.edu.au/08365/h&p1bmol.htm on Sep. 1)

Disaccharides

• made from two monosaccharides during dehydration reaction
• most common disaccharide: sucrose, "a glucose molecule linked to a fructose molecule" (Campbell, 96)
• sucrose "is a major carbohydrate in plant sap, and it nourishes all parts of the plant" and the ingredient of table sugar (Campbell, 96)
• sucrose can be used as glucose and fructose immediately once consumed

image of starch (taken from http://www.sciencecollege.co.uk/SC/biochemicals.html on Sep. 1)

Polysaccharides (a.k.a. complex carbohydrates) - "long chains made up of simple sugar monomers" (Campbell, 96)

Starch

• a polysaccharide, "starch is found in plant cells and consists only of glucose monomers" (Campbell, 96).
  
• starch chains, coiled like telephone lines outside the cells, are sugar stockpiles
• humans and many animals absorb stored glucose of starch by breaking down starch chains in digestive systems
• items with much starch include potatoes, rice, and corn
• starch in plant cells, no animal cells
  

Polysaccharide

• starch: in plant cells
  
• glycogen: in animal cells; "like starch, is a chain of many glucose monomers... [but] is more highly branched than a starch polymer. Glycogen in stored in liver and muscle cells" (Campbell, 96)
  
• cellulose: plant, serves as building blocks; "They protect cells and stiffen the plant, preventing it from flopping over" (Campbell, 97). A.k.a fiber, not digestible by humans and many animals, helps digestive system, no direct nutrients
  
• all made from glucose, but bonding is different; cellulose stronger thanks to hydrogen bonds between monomers, "forming cable-like fibers in the tough walls that enclose plant cells" (Campbell, 97).
• "Most carbohydrates are hydrophilic" thanks to the hydroxyl groups included in sugar units (Campbell, 97).
• Cellulose do not melt in water, unlike monosaccharides and disaccharide.
  

Forgive the incorrect image citations, but shouldn't the essence that I try not to take credit more important? Ha ha ha ha.... this is really tiring.... could we go back a couple decades, to the times of pen and paper?

Concept check:

1. Differences of mono and disaccharides. Give examples of each. Monosaccharides (glucose) are sugars containing 1 sugar unit, while a disaccharide (sucrose) contains 2 units, or 2 monosaccharides.
   
2. Compare starch, gylcogen, and cellulose. All 3 made from glucose, the difference is in their structures. Structures directly affecting function, they are all used for different purposes. Starch is the form in which plants store energy, and gylcogen, the form for animals. Cellulose is a special polysaccharide that reinforces cell-walls and assist human digestion. Commonly known as fiber.
   
3. How do animals store excess glucose molecules? Animals store excess glucose by putting them together, forming larger carbohydrates, or in this case, gylcogen.