PAIN and Analgesia* Control* Paracrine Factors* PARAXIAL MESODERM and Intermediate mesoderm* Somites and Their Derivatives* Parkinson Disease* Petals* Pharmacogenetics* PHENYLKETONURIA Phenylketonuria*

PHEROMONES in Vertebrates* PHLOEM Structure and Function* PHOSPHOLIPASES Degradation of Membrane Phospholipids* PLANT Life Cycles* POLARITY Anterior-Posterior* Dorsal-Ventral* POLYMERASE CHAIN REACTION PCR* POLYTENE CHROMOSOMES Polytene Chromosomes* Pollination* POPULATION GENETICS of Modern Human Evolution* Prions*

PRONUCLEI Mammalian   ◊ Nonequivalence* Proprioceptive Sensory Feedback* Protease Complexes* PROTEOMICS Description PROTEIN STRUCTURE Classification* Quaternary   ◊ Subunit–Subunit Interactions* PROTEIN PHOSPHORYLATION and Long-term Synaptic Plasticity* PROTEIN–DNA INTERACTION Role* PROTEIN–NUCLEIC ACID INTERACTION Major Groove Recognition Determinants Pyruvate Dehydrogenase Complex