3B_Carbohydrates+(notes)

You will need to:
 * Understand the chemical nature of carbohydrates;
 * Describe the structure and function of carbohydrates;
 * Recall the molecular formulae;
 * Understand that molecular biosynthesis builds new molecules   through energy-dependent rearrangements of matter;
 * Understand the formation of glycosidic bonds;
 * Describe their dietary importance in living organisms;
 * Describe the roles of carboydrates as energy stores, and, in protection, waterproofing, insulating and buoyancy;
 * Understand that pentose and hexose’s are monosaccharides and have roles as monomers;



**Carbohydrate characteristics**

 * Contain the elements C, H, O: CnH2nOn __(n=any number depending on mono, di or polysaccharide)__
 * They are either made from single monosaccharide monomers or from several monosaccharides joined together
 * Monosaccharides are: Trioses – C3H6O3 e.g. glyceraldehyde Pentoses – C5H10O5 e.g. deoxyribose Hexoses – C6H12O6 e.g. glucose, fructose

Carbohydrates are classified as:
 * 1) **Monosaccharides** eg glucose, fructose, galactose
 * 2) **Disaccharides** eg sucrose, maltose, lactose
 * 3) **Polysaccharides** eg cellulose, glycogen, starch
 * 4) Other polysaccharides and polysaccharide derivatives eg pectins, chitin and mucopolysaccharides

**Disaccharides**
What are the other disaccharides?

**Polysaccharides**
- made from condensing many similar monosaccahrides - Polymerization



**Reactions**
What are the various reactions that take place in the formation of all these different forms.

**Starch & Glycogen**

 * Their molecules have many side branches where glucose molecules can be removed from their tips (by enzymes)
 * Their insolubility stops them interfering with osmosis
 * Their compactness provides an efficient way to store lots of glucose for future cellular respiration


 * || [[image:rambio:starch_granules2.jpg height="222" caption="Glycogen granules in skeletal muscles"]] ||
 * Glycogen granules in skeletal muscles ||  || [[image:rambio:starch_granule.jpg height="231" caption="starch_granule.jpg"]] ||
 * Glycogen granules in skeletal muscles || Starch grains in potato cells ||



“Animal Starch” - storage form of carbohydrate in animals and fungi. Formed from condensation of many glucose molecules


 * Cellulose**
 * Made from long, straight chains of glucose
 * Chains cross-linked by H-bonds which holds them tightly together (excludes water)
 * Chemically very inert and insoluble – few ‘tips’ on molecule make it difficult to digest
 * Many molecules form strong fibrils
 * Only some bacteria, fungi and  a very small number of  animals can secrete cellulase  enzymes.

PAUSE - VIDEO

**Function of Starch**

 * 1) Form supporting structures E.g. cellulose cell wall.
 * 2) Source of energy - glucose is the raw material needed for cellular respiration yielding ATP, the energy molecule.
 * 3) Converted into other organic compounds E.g. amino acids
 * 4) For formation of nucleic acids
 * 5) Synthesis of lubricants, e.g. mucus
 * 6) Produce nectar in some flowers.

**Fibre**

 * Indigestible e.g. cellulose
 * Provides bulk to intestinal contents
 * Aids in peristalsis - rhythmic wave like contractions along the gut
 * Prevents constipation
 * Sources : fresh fruits, vegetables, bran, cereals, wholemeal bread

VIDEO Starch = many "simple sugars" Reduction sugars: ability to reduce other chemicals by exchange of electrons (e.g. copper experiment - series of colour change)