2. chemical basis of life


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2. chemical basis of life

  1. 2. <ul><li>Water </li></ul><ul><ul><li>found in largest quantities (50-90%) </li></ul></ul><ul><ul><li>normal body temperature- 37 o C or 98 o F </li></ul></ul><ul><ul><li>(<body temperature or hypothermia- metabolic functions bec slower and finally stop) </li></ul></ul><ul><ul><li>(>body temperature or hyperthermia- proceed too rapidly and body proteins break down) </li></ul></ul><ul><ul><li>death at either extreme </li></ul></ul>Inorganic Compounds
  2. 3. <ul><li>Uses of Water </li></ul><ul><ul><li>vehicle for chemical reactions </li></ul></ul><ul><ul><li>regulation of body temperature </li></ul></ul><ul><ul><li>excretion of waste </li></ul></ul><ul><ul><li>acts as solvent </li></ul></ul><ul><ul><li>transport of food, nutrients and essential gases </li></ul></ul><ul><ul><li>protection </li></ul></ul><ul><ul><li>serves as base for body lubricants </li></ul></ul>
  3. 4. <ul><li>Water is a polar molecule </li></ul>THE PROPERTIES OF WATER Which leads to hydrogen bonding
  4. 5. <ul><li>Hydrogen bonds make liquid water cohesive </li></ul><ul><ul><li>Due to hydrogen bonding, water molecules can move from a plant’s roots to its leaves </li></ul></ul><ul><ul><li>Insects can walk due to surface tension created by cohesive water molecules </li></ul></ul>
  5. 6. <ul><li>Like no other common substance, water exists in nature in all three physical states: </li></ul><ul><ul><li>as a solid </li></ul></ul><ul><ul><li>as a liquid </li></ul></ul><ul><ul><li>as a gas </li></ul></ul>
  6. 7. Water is a universal solvent. - It is able to dissolve a large number of different chemical compounds.
  7. 8. <ul><li>Ions - 5% of body weight; dissolved in water </li></ul><ul><ul><ul><li>Important ions: K, Mg, PO 4 , SO 4 , bicarbonates, Na, Cl </li></ul></ul></ul><ul><ul><ul><li>most plentiful salts- Calcium Phosphates (in bones, teeth) </li></ul></ul></ul>Inorganic Compounds
  8. 9. <ul><li>Uses of Inorganic Materials </li></ul><ul><ul><li>provide inorganic chemicals for cellular reactions </li></ul></ul><ul><ul><li>necessary for operation of some cellular activities </li></ul></ul><ul><ul><li>maintenance of proper osmotic condition </li></ul></ul><ul><ul><li>acid-base balance </li></ul></ul><ul><ul><li>formation of bones </li></ul></ul><ul><ul><li>formation of thyroxine </li></ul></ul><ul><ul><li>transport of CO 2 and O 2 </li></ul></ul>
  9. 10. Organic Compounds carbon-containing ; exceptions: CO 2 , CO and carbides Carbohydrates Lipids Proteins
  10. 11. <ul><li>Carbohydrates – C,H,O; C is in the same ratio as H 2 O= (C n (H 2 O) n ) </li></ul><ul><ul><li>oxidize easily and are the most readily-available energy/heat source </li></ul></ul><ul><ul><li>serve as important structural material in some animals and all plants </li></ul></ul><ul><ul><li>literally means ‘ hydrated carbon ’ </li></ul></ul><ul><ul><li>made up of repeating units called sugars . </li></ul></ul><ul><ul><li>Excess CHO--  glycogen or fat (stored in liver or muscles) </li></ul></ul>Note : The larger the carbohydrate molecule, the less soluble it is in water. Organic Compounds
  11. 12. Classification of Sugars according to size and solubility <ul><ul><li>Monosaccharides - simple sugars; single ring structures with 3-7 carbon atoms </li></ul></ul><ul><ul><li>CHO in a ratio of 1:2:1 </li></ul></ul><ul><ul><li>Basic units of carbohydrates </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><li>Glucose, Fructose, galactose- C 6 H 12 O 6 (hexoses) </li></ul><ul><li>Deoxyribose, ribose – pentose ( 5C) </li></ul>
  12. 13. <ul><ul><li>2. Disaccharides - double sugars; made up of two monosaccharides joined together by dehydration synthesis </li></ul></ul><ul><ul><ul><li>Have to be hydrolyzed to be broken down to monosaccharides </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><li> glucose + fructose = sucrose (table sugar) </li></ul><ul><li>2C 6 H 12 O 6 ----  C 12 H 22 O 11 + H 2 O </li></ul><ul><li>lactose( milk sugar)= gluc + gal </li></ul><ul><li>maltose(malt sugar)= gluc + gluc </li></ul>Classification of Sugars according to size and solubility
  13. 15. <ul><ul><li>Polysaccharides - long chains of simple sugars (polymers) linked together by dehydration synthesis </li></ul></ul><ul><ul><li>individual units called monomers </li></ul></ul><ul><ul><li>large, insoluble molecules </li></ul></ul><ul><ul><li>lack sweetness of mono- and disaccharides </li></ul></ul><ul><li>Examples: </li></ul><ul><li>Starch - storage form of CHO in plants (made up of long glucose chains) </li></ul>Classification of Sugars according to size and solubility
  14. 16. Hydrolysis: Amylase maltase Starch - ------- maltose -------2 glucose Glycogen - storage CHO of animal tissues - large molecule and highly branched - can easily be broken down to yield glucose Cellulose – most abundant organic molecule in the planet - chief structural material in plants; provides rigidity - indigestible in man due to complex arrangement of glucose - provides bulk and stimulates bowel movement - enzyme cellulase from bacteria and protozoans digest cellulose to yield glucose
  15. 17. <ul><li>Chitin </li></ul><ul><ul><li>Second most abundant organic compound on earth. </li></ul></ul><ul><ul><li>Makes up the hard outer skeletons of certain animals </li></ul></ul><ul><li>ex. Insects, crabs, lobsters </li></ul><ul><ul><li>Resistant to breakdown by bacteria and animals </li></ul></ul>
  16. 18. Lipids insoluble in water but dissolve readily in organic solvents as alcohol, chloroform and ether -CHO, but with less O and more C atoms--  more heat
  17. 19. <ul><li>Three forms of Lipids </li></ul><ul><ul><li>Neutral fats - or triglycerides; Fatty acids and glycerol as building blocks (3:1 ratio) </li></ul></ul><ul><li> - most common; for heat loss and protection </li></ul><ul><li> - non-polar and do not mix with water </li></ul><ul><ul><ul><li>may be solid ( fats ) or liquid ( oils ) according to length of fatty acid chains and degree of saturation: </li></ul></ul></ul>
  18. 20. <ul><li>Saturated - with single bonds between C atoms </li></ul><ul><li>-longer fatty acid chains; solid at 20 o C </li></ul><ul><li>- animal fats as butter fat and meat fats </li></ul><ul><li>- encourage build-up of plaques in walls and vessels </li></ul>
  19. 21. <ul><li>Unsaturated - with double/triple bonds between C atoms </li></ul><ul><li>- short FA chains; liquid at room temperature </li></ul><ul><li>- plant sources as olive, peanut, corn </li></ul><ul><li>-margarine as substitute for butter </li></ul>
  20. 22. ** fat deposits in subcutaneous tissue – thicker layer in women
  21. 23. <ul><ul><li>Phospholipids -modified triglycerides with two FA chains + 1 phosphorus-containing group </li></ul></ul><ul><li>- with polar heads and non-polar (hydrocarbon) tails </li></ul><ul><li>- phosphate groups in heads attract water and ions </li></ul><ul><li>- in cell membrane; regulates transport </li></ul>
  22. 24. <ul><ul><li>Steroids – lipids made up of solid alcohol with no fat-like properties </li></ul></ul><ul><li> - fat-soluble and contain little O </li></ul>
  23. 25. Cholesterol - from animal products; CV disorders - component of cell membranes - raw material for Vitamin D synthesis, other steroid hormones ( estrogen, progesterone,testosterone, cortisol and aldosterone) - manufactured in liver, most abundant in brain - attaches to protein to form lipoprotein before it can circulate
  24. 26. <ul><li>Two types of Lipoproteins </li></ul><ul><li>High Density Lipoproteins (HDL) </li></ul><ul><li>- more CHON, less lipid </li></ul><ul><li>- brings cholesterol to liver for elimination </li></ul><ul><li>‘ good cholesterol </li></ul><ul><li>Low Density Lipoproteins (LDL) </li></ul><ul><li>- less CHON, more lipid </li></ul><ul><li>-clogs blood vessels </li></ul><ul><li>- ‘bad cholesterol’ </li></ul>
  25. 27. <ul><ul><li>CHON, sometimes sulfur, phosphorus and trace metals as iron and copper; second most abundant (10-20% of cell mass) </li></ul></ul><ul><ul><li>Building blocks: amino acids --  about 20 aa </li></ul></ul><ul><ul><ul><li>Essential aa ( 8)- taken in with food </li></ul></ul></ul><ul><ul><ul><li>Non-essential (12)- synthesized by body </li></ul></ul></ul><ul><ul><li>aa can be a base (proton acceptor) or an acid (proton donor) </li></ul></ul><ul><ul><li>linked by peptide bonds which break during hydrolysis </li></ul></ul><ul><ul><li>Deficiency: brittle nails, rough scaly skin, rough lackluster hair </li></ul></ul><ul><ul><li>Extreme deficiency: kwashiorkor </li></ul></ul>Proteins
  26. 28. <ul><li>Functions of Proteins </li></ul><ul><ul><ul><ul><li>constitute framework of cytoplasm </li></ul></ul></ul></ul><ul><ul><ul><ul><li>releases energy when oxidized </li></ul></ul></ul></ul><ul><ul><ul><ul><li>source of enzymes and hormones </li></ul></ul></ul></ul><ul><ul><ul><ul><li>repair of damaged/worn-out tissues </li></ul></ul></ul></ul>
  27. 29. <ul><li>Fibrous Protein </li></ul><ul><ul><li>with extended strand-like appearance </li></ul></ul><ul><ul><li>linear, insoluble in water and very stable </li></ul></ul><ul><ul><li>provides support and tensile strength to body tissues </li></ul></ul><ul><ul><li>‘ structural proteins’; most exhibit 2 o structure, others 4 o </li></ul></ul><ul><ul><li>Examples: leather, hair, nuclear membrane, ER, mitochondrion </li></ul></ul>Two types of Proteins
  28. 30. <ul><li>Globular Protein </li></ul><ul><ul><li>compact, spherical, exhibit 3 o to 4 o structures </li></ul></ul><ul><ul><li>water soluble, mobile, chemically active </li></ul></ul><ul><ul><li>‘ functional proteins’ </li></ul></ul><ul><ul><li>dissolved in cellular fluids </li></ul></ul><ul><ul><li>Examples: antibody molecules, enzymes, plasma prteins </li></ul></ul>Two types of Proteins
  29. 31. <ul><ul><ul><li>DNA –chief hereditary material </li></ul></ul></ul><ul><ul><ul><li>RNA- important in protein synthesis </li></ul></ul></ul><ul><ul><ul><li>nucleotides as structural units </li></ul></ul></ul><ul><ul><ul><li>nucleotide- nitrogen base, pentose sugar, phosphate group </li></ul></ul></ul>Nucleic Acids