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Structure/Function of Cell Components

Structure/Function of Cell Components. Living things are made of: Carbohydrates Lipids Proteins Nucleic acids CHNOPS Carbon Hydrogen Nitrogen Oxygen Phosphorous Sulphur. Basic Chemistry. Strong Bonds. Atoms make bonds Ionic loss/gain of electrons Covalent electrons are shared

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Structure/Function of Cell Components

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  1. Structure/Function of Cell Components • Living things are made of: • Carbohydrates • Lipids • Proteins • Nucleic acids • CHNOPS • Carbon • Hydrogen • Nitrogen • Oxygen • Phosphorous • Sulphur

  2. Basic Chemistry Strong Bonds • Atoms make bonds • Ionic loss/gain of electrons • Covalent electrons are shared • Polar covalent – unequal sharing of the electrons • Makes the atoms have a partial charge (polarity) • Hydrogen bonds • Between a polar covalently bonded hydrogen atom (e.g. to N or O) and another polar covalently bonded atom e.g. oxygen in a carbonyl group. • Polar covalent bonds, only a partial charge so relatively weak • Van der waals forces • Induced polarity (e.g. in C-H bond) • Hydrophobic Interactions • Non-polar groups tend to cluster together (away from water) • Polar groups tend to move towards water Weak Bonds

  3. CARBOHYDRATES

  4. Carbohydrates • C, H, O • (CH2O)n • Monosaccharides - one monomer • Form rings in solution • Disaccharides - two monomers • Polysaccharides - many monomers • Monomers contain • 5 Carbon atoms - pentose • 6 carbon atoms - hexose

  5. Carbohydrates • Saccharides can exist in solution as linear molecules or rings. • They interconvert between the two forms, but at equilibrium, 99% will be ring

  6. Structural Variation in Carbohydrates • Special carbons • Carbon atoms 1-5 are chiral (optically active) i.e. OH and H groups on the C atoms can be ordered differently. • For C atoms 2-4 the arrangement of OH and H groups determines the monosaccharide . • Orientation of OH on Carbon 5 (in Hexoses) confers D (dextro rotatory) or L (laevorotatory) forms • D points right • L points left • Orientation of OH on Carbon 1 (in Hexoses) determines  (down) or  (up)

  7. Numbering 6 5 4 1 3 2

  8. The molecules are isomers, they differ in the orientation of H and OH on C2-4.

  9. Note Fructose differs in the position of the carbonyl – important in forming rings

  10.  down,  up The OH group on the carbon next to the oxygen (C1)

  11. Forming Rings 1 Rings form between C1 and C5. An O atom acts as a bridge (hence the 6 member ring). 2 Complex rearrangement 3 4 5 6

  12. Disaccharides • Two monosaccharides join together with a glycoside bond • Dehydration (condensation) reaction (elimination of water) • e.g. maltose (2 x glucose) •  -D-glucose joined to  -D-glucose • join at the C1 () and C4 atoms • 1-4 glycoside bond

  13.  1,4, glycosidic bond - cellobiose  1,2 glycosidic bond -sucrose  1,6, glycosidic bond

  14. Polysaccharides • 3 major ones of interest • Starch • Glycogen • Cellulose

  15. STARCH • Comprised two components • Soluble part (20%) - AMYLOSE • Continouous unbranched chain of glucose units (up to 300) joined by 1-4 glycoside bonds. • Insoluble part (80%) – AMYLOPECTIN • Shorter 1-4 chains (24-30), with 1-6 branching Starch, being insoluble exerts no osmotic pressure, so is useful as a storage polysaccharide

  16. GLYCOGEN • Animal storage polysaccharide • Similar to amylopectin, • Lower molecular weight • More highly branched • 1-4 chains (up to 10), with 1-6 branching

  17. CELLULOSE • Linear polymer of glucose units (up to 2800) •  1,4, glycosidic bonds • Cellulose fibre - parallel strands held together by hydrogen bonds

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