IB DP Biology: SL复习笔记2.6.4 Skills: DNA, RNA & Protein Synthesis

Drawing DNA & RNA Nucleotides & DNA Double Helix

Drawing simple diagrams of the structure of single nucleotides of DNA and RNA

  • Simple shapes can be used to draw the main building blocks of nucleotides and the DNA double helix
    • Advanced drawing skills are not required!
  • Pentagons can represent pentose sugars
  • Circles can represent phosphates
    • Often shown as a circle with the letter P inside: ℗
  • Rectangles can represent bases
  • Covalent bonds can be shown with solid lines
  • Hydrogen bonds can be shown with dashed lines
    • Or with complementary shapes that fit together (see diagrams)


Simple shapes can be used to represent parts of nucleotide molecules


Two nucleotides shown bonded together covalently within a strand


When drawing the base pairing, the opposite strand should be antiparallel to the first. The presence of hydrogen bonding is shown, but the numbers/lengths of bonds is not required


An alternative way to draw a DNA strand is to use complementary shapes for the bases

Exam Tip

Simple, hand-drawn shapes will suffice in an exam. Expert tip - a large drawing is always easier for an examiner to read (and award marks for) than a small one!Read the question carefully; examiners often want a whole nucleotide to be identified in your diagram and to ensure your diagram includes all 4 complementary bases.You don't have to remember the number of hydrogen bonds between the bases.Also, remember to draw DNA strands as antiparallel (one upside-down versus the other) but you don't have to be able to draw a helix shape!