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Biologically Important Molecules

organic compounds - macromolecules made of subunits in living organisms  

  • carbohydrates, proteins, lipids, nucleic acids
  • dehydration synthesis - water molecule removed to bond 2 subunits
  • hydrolysis - exothermic reaction where water is added to break bonds between subunits
  • different structures and arrangments give compounds different characteristics

controlled experiments - has controls used for comparison  

  • unknown solution - may or may not contain the substance that is being tested for
  • positive control - contains the substance that is being tested for; shows what a positive test should look like
  • negative control - doesn't react in the test; shows what a negative result should look like

carbohydrates - molecules made of C, H, and O in ratio 1:2:1  

  • monosaccharides - simple sugars
  • disaccharides - paired monosaccharides
  • polysaccharides - linking together 3 or more monosaccharides
  • reducing sugars - monosaccharides that have free adlehyde (-CHO) or ketone (-C=O) groups that reduce weak oxidizing agents
  • Benedict's test - identifies reducing sugars that can reduce the cupric ions in Benedict's reagent into cuprous oxide
  • iodine test - iodine-potassium iodide reacts w/ coiled molecules of starch to become bluish black; doesn't react w/ other carbohydrates as much

proteins - made of amino acids  

  • each amino acid has amino group, carboxyl group, and variable side chain
  • peptide bond - forms between amino group and carboxyl group of 2 amino acids
  • Biuret test - peptide bonds of proteins produce a violet color when in contact w/ the copper II found in Biuret reagent; individual amino acids do not react

lipids - nonpolar molecules w/ many C-H bonds  

  • dissolve in nonpolar solvents
  • fats (triglycerides) - made of glycerol and 3 fatty acids
  • tests based on lipid's ability to change color w/ fat-soluble dyes (ex. Sudan IV)
  • grease-spot test - lipids produce translucent grease-marks on unglazed paper

nucleic acids - made of nucleotide subunits  

  • either DNA or RNA (differences in sugar structure and organic bases)
  • Dische diphenylamine test - makes deoxyribose into another molecule that bonds w/ diphenylamine to make a blue color
Subject: 
Biology
Subject X2: 
Biology

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