Illustration created for the fourth edition of Biology: How Life Works, published by Macmillan. Authors: James Morris; Daniel Hartl; Andrew Knoll; Robert Lue; Melissa Michael; Andrew Berry; Andrew Biewener; Brian Farrell; N. Michele Holbrook; Jean Heitz; Mark Hens; John Merrill; Randall Phillis; Debra Pires; Elena Lozovsky; Jessica Liu. Copyright Macmillan