To test a hypothesis, a scientist could... a- make observations

b- perform experiments

c- look to the scientific literature to find data

d- all of the above

Six amino acids have side chains that are polar but not charged. these are serine (ser), threonine (thr), cysteine (cys), asparagine (asn), glutamine (gln), and tyrosine (tyr). these amino acids are usually found at the surface of proteins, as discussed in the proteins 2 module.