different amino acids There are 20 common amino acids Amino acids can join via peptide bonds Several amino acids occur only rarely in proteins Some amino acids are not found in proteins 3D structure of amino acids Why is the 3D structure (stereochemistry) of amino acids important? Amino acids appear in chiral (mirror image) except for glycine where the R = Hydrogen Chirality of amino acids can only be seen in 3D structure The position of amino group on the left or right side of the α-carbon
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Several naturally occurring penicillins have now been isolated‚ and numerous derivatives of these substances have been synthetically produced. All have structures containing a four-membered β-lactam ring (4 membered cyclic amide) fused with a five-membered thiozolidine ring. The carbon atom of the amide on the β-lactam ring can be bonded to any substituent‚ called the ’R-group’. Penicillins as well as cephalosporins are called beta-lactam antibiotics and are characterized by three fundamental structural
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elements that had not been discovered yet and it contained the atomic mass of the elements. DISADVANTAGES: * When Dmitri put the elements in order of atomic mass‚ he had trouble getting iodine because iodine was similar properties to chlorine and bromine. But iodine had a low atomic mass. So iodine could not be in his rows. This caused Dmitri to break his own rule; he made for the periodic table. DISADVANTAGES: * When Dmitri put the elements in order of atomic mass‚ he had trouble getting
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destruction of the stratospheric ozone is affected (Dobson‚ 2005). Despite this‚ an5thropogewnic causes are taken as the main causes of the depletion at the moment. It is believed that the natural phenomenon causes a temporary destruction but Chlorine and Bromine released as CFCs have more effects. These Chlorofluorocarbons cause effects that cannot be reversed they cannot mix with rain drops or be destroyed by other chemicals. Chlorofluorocarbons can survive in the air for 20 to 120 years causing more destruction
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Competitive Nucleophiles Introduction: The purpose of this experiment was to compare the relative nucleophilicities of chloride ions and bromide ions in two different reactions. One reaction involved n-butyl alcohol and the other involved t-pentyl alcohol. We performed the reactions and compared the percentages of alkyl chloride and alkyl bromide in the product. To perform this experiment‚ we used methods including heating reaction mixture under reflux‚ extraction using a separatory funnel
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Ozone Depletion: An Introduction Planet Earth has its own natural sunscreen that shields us from the sun’s damaging ultraviolet radiation. It’s called the ozone layer: a fragile band of gases beginning 15 kilometres above our planet‚ and reaching up to the 40-kilometre level. Human activities have caused a substantial thinning of this protective covering — not only over the North and South Poles‚ but right over our heads. Stopping ozone layer depletion is one of the major challenges facing the
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drops of the NaOH solution 6. Stir for 20 min 7. Add to an ice bath until crystallization occurs 8. Filter the crude product 9. Recrystallize with 2 mL of EtOH 10. Filter pure product and collect MP and mass 11. Perform a saturation test with a bromine and potassium permanganate solution 12. Obtain NMR from instructor and identify peaks Apparatus: Post Lab: Observations:
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Ngoc Pham Chem162B Lab #2: Trends in Periodic Table Date: 01/10/2011 Lab partner: Ian Bauer Result Section: Table I: The solubility of the alkaline earth metal ions | SO42- | CO32- | C2O42- | IO32- | Mg2+ | S | I | S | S | Ca2+ | I | S | S | I | Sr2+ | S | S | S | I | Ba2+ | I | I | I | S | Key: I- insoluble‚ S-soluble Table II: Color of water (Halide) and Halogen (Hexane) layers | Cl2 | Br2 | I2 | Hexane layer | Clear | orange | Pink | Water layer | Clear‚
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Cooling Water Problems and Solutions Course No: M05-009 Credit: 5 PDH A. Bhatia Continuing Education and Development‚ Inc. 9 Greyridge Farm Court Stony Point‚ NY 10980 P: (877) 322-5800 F: (877) 322-4774 info@cedengineering.com COOLING WATER PROBLEMS AND SOLUTIONS Water is used in cooling systems as a heat transfer medium and frequently also as the final point to reject heat into the atmosphere by evaporating inside cooling towers. Depending on the quality of available fresh
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HSC Chemistry Topic 1 PRODUCT ON of MATERIALS What is this topic about? To keep it as simple as possible‚ (K.I.S.S.) this topic involves the study of: 1. POLYMERS FROM PETROCHEMICALS & BIOMASS 2. ALTERNATIVE FUELS - ETHANOL & THE ALKANOLS 3. REDOX CHEMISTRY & BATTERIES 4. RADIOACTIVITY & ITS USES ...all in the context of society’s use of energy and materials but first) an introduction ... In the previous topic in the Preliminary Course‚ you learnt about carbon chemistry of petroleum Then you
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