3d
biochemistry
biology
biomolecule
brain
cartoon
chain
chemistry
coil
color
computer generated
control
disease
fatal
graphic
health
helix
illustration
isolated
mad cow
medicine
model
molecule
pathology
peptide
prion
protein
red
ribbon
science
secondary
shape
sheet
spongiform encephalopathy
strand
structure
tertiary
three dimensional
transmissible
white background
yellow