Describe the differences between amino acids and nucleotides
Main points | |
Key idea: | Components |
(each) Amino acid: · Has an amino (NH) gp, a carboxyl (COOH) gp, a H atom & a R gp attached to a central α carbon atom (each) Nucleotide: · Made up of a pentose sugar, a nitrogenous base & a phosphate gp · Ref to 3 phosphate gps in each ‘free’ nucleotide | |
Key idea: | Ionization |
Amino acids: · In H2O, COOH & NH gps ionize, form –ve charged & +ve charged gp, respectively · Ref to amphoteric property (i.e. –ve charged COOH accepting a H+, -ve charged NH donating H+); i.e. aa act as pH buffer Nucleotides: · In H2O, the phosphate gp is -ve charged, hence nucleotide is soluble in H2O · Also result in net -ve charges of RNA & DNA polynucleotides (DNA migrate toward +ve electrode during gel electrophoresis due to -ve charges along sugar phosphate backbone) | |
Key idea: | Types |
Amino acids: · 20 (naturally occurring) aa distinguished by identity of R gp · Ref to aa categorized into polar uncharged, non-polar uncharged & charged (basic or acidic) aa Nucleotides: · 4 diff types of nucleotides in DNA distinguished by base - cytosine, guanine, thymine & adenine · In RNA, bases are same except for uracil replacing thymine | |
Key idea: | Formation of bonds |
Amino acids: · Diff R gps allow for formation of ionic, H, disulfide bonds or hydrophobic interactions b/w aa; result - sec, tertiary & quarternary struc of a protein Nucleotides: · H bonds b/w complementary bases (C and G, A and T), result - formation of double helix struc of DNA | |
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) For this type of essay question, you could answer in a table format too (v) If time permits, draw and label a general amino acid and nucleotide | |
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