phospholipid.mp

% a simple lewis diagram of a phospholipid
numeric u;
u = 1pc;

beginfig(0)
  % hydrophilic head
  label(btex ${\rm CH}_{2}$ etex, (0,0));
  draw (u, 0)--(1.75u,0);
  label(btex ${\rm CH}$ etex, (2.5u, 0));
  draw (3.25u, 0)--(4u, 0);
  label(btex ${\rm CH}_{2}$ etex, (5u, 0));
  draw (5u, 0.5u)--(5u, 1.5u);
  label(btex ${\rm O}$ etex, (5u, 2u));
  draw (5u, 2.5u)--(5u, 3.5u);
  label(btex ${\rm P}$ etex, (5u, 4u));
  draw (4.6u,3.9u)--(3.4u,3.9u);
  draw (4.6u,4.1u)--(3.4u,4.1u);
  label(btex ${\rm O}$ etex, (3u, 4u));
  draw (5.5u, 4u)--(6.5u,4u);
  label(btex ${\rm O}$ etex, (7u, 4u));
  draw (5u, 4.5u)--(5u, 5.5u);
  label(btex ${\rm R}$ etex, (5u, 6u));
  draw (0,-0.5u)--(0,-1.5u);
  label(btex ${\rm O}$ etex, (0, -2u));
  draw (5u,-0.5u)--(5u,-1.5u);
  label(btex ${\rm O}$ etex, (5u, -2u));
  % hydrophobic tails
  draw (0,-2.5u)--(0,-3.5u);
  label(btex ${\rm C}$ etex, (0, -4u));
  draw (0.5u, -3.9u)--(1.5u,-3.9u);
  draw (0.5u, -4.1u)--(1.5u,-4.1u);
  label(btex ${\rm O}$ etex, (2u, -4u));
  draw (0,-4.5u)--(0,-5.5u);
  label(btex ${\rm CH}_{2}$ etex, (0,-6u));
  draw (0,-6.5u)--(0,-7.5u);
  label(btex ${\rm CH}_{2}$ etex, (0,-8u));
  draw (0,-8.5u)--(0,-17.5u);
  label(btex ${\rm CH}_{3}$ etex, (0,-18u));
  % tail 2
  draw (5u, -2.5u)--(5u,-3.5u);
  label(btex ${\rm C}$ etex, (5u, -4u));
  draw (5.5u, -3.9u)--(6.5u,-3.9u);
  draw (5.5u, -4.1u)--(6.5u,-4.1u);
  label(btex ${\rm O}$ etex, (7u, -4u));
  draw (5u, -4.5u)--(5u,-5.5u);
  label(btex ${\rm CH}_{2}$ etex, (5u,-6u));
  draw (5u, -6.5u)--(5u,-7.5u);
  label(btex ${\rm CH}_{2}$ etex, (5u,-8u));
  draw (5u, -8.5u)--(5.25u,-9.5u);
  label(btex ${\rm CH}$ etex, (5.5u,-10u));
  draw (5.5u,-10.5u)--(5.75u,-11.5u);
  label(btex ${\rm CH}$ etex, (6u,-12u));
  draw (6u, -12.5u)--(6.25u,-13.5u);
  label(btex ${\rm CH}_{2}$ etex, (6.5u,-14u));
  draw (6.5u, -14.5u)--(6.75u,-15.5u);
  label(btex ${\rm CH}_{2}$ etex, (7u,-16u));
  draw  (7u, -16.5u)--(7.25u,-17.5u);
  label(btex ${\rm CH}_{3}$ etex, (7.5u,-18u));
endfig;
end;