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- P bodies
- p53
- [tumor suppressor gene] [detecting DNA damage]
- Pachytene
- Pacinian corpuscle
- Packaging cell (for retroviral gene vectors)
- Pain
- Paleozoic era
- Palindromes
- Pancreas
- [hormones of] [digestive enzymes]
- Pandemic
- Paneth cells
- Pangaea
- Panspermia
- Para-aminobenzoic acid (PABA)
- Paracrine
- Refers to the influence on a cell of chemical signals released by neighboring cells. Compare autocrine and endocrine.
- Parainfluenza virus (PIV)
- Paralogous genes
- Genes in one species that have arisen by duplication of an ancestral gene. Example: genes encoding olfactory receptors. Compare orthologous genes.
- Paramecium caudatum
- Parasitism
- [how parasites evade host defenses]
- Parasympathetic nervous system
- Parathion
- Parathyroid hormone (PTH)
- Parenchyma
- p arm
- Parthenogenesis
- [ and imprinting ]
- Passive immunity
- Patch clamp technique
- Patch test (for contact dermatitis)
- Pathfinder mission to Mars
- Pathogen
- Disease-causing organism or virus.
- Pathogen-Associated Molecular Patterns (PAMPs)
- Pattern Recognition Receptors (PRRs)
- Pax-6
- PCR (polymerase chain reaction)
- P element
- Pemphigoid and pemphigus
- Penicillin
- Pentose
- Pepsin
- Peptide bond
- Peptidoglycan
- Perforin
- Pericycle
- Period (per) gene
- Peripheral membrane protein
- [Schematic (48K)]
- Peripheral nervous system, human
- Peroxisome-proliferator-activated receptors (PPARs)
- Peroxisomes
- [ peroxisomal targeting signal (PTS) ]
- Peroxyacetyl nitrate (PAN)
- Peroxyl (or peroxy) radical
- PERV (porcine endogenous retrovirus)
- Peyote
- pH
- [effect on enzyme action]
- Phage display
- Phagocytosis
- Pharyngula
- Phencyclidine (PCP)
- Phenotype
- Appearance of an organism, resulting from the interaction of its genotype and its environment.
- Phenylalanine
- Phenylketonuria (PKU)
- Pheromones
- [insect] [in humans]
- Philadelphia chromosome (Ph1)
- PhiX-174
- Phloem
- [function in translocation] [structure] [in roots]
- Phosphatase
- Enzyme that removes phosphate groups
- Phosphate group
- Phospholipids
- Photoperiodism, in plants
- Photophosphorylation
- Photorespiration
- Photosynthesis
- [Calvin cycle] [light reactions] [energy relationships in]
- Photosystems I & II
- Phototaxis
- Phototropin
- [ and phototropism ] [ and stomatal opening ]
- Phototropism
- Phylogenetic tree
- [of living hominoids]
- Phylogeny
- Evolutionary history of a species.
- Phylum
- Physiology
- Study of the processes occurring in living organisms.
- Phytochrome
- [in etiolation] [in photoperiodism]
- PIF3 (phytochrome-interacting factor 3)
- Pigment
- Substance that absorbs light, often selectively.[antenna pigments]
- Pilin
- Pineal gland
- Pinocytosis
- PIN proteins
- Pistil
- PISTILLATA (PT)
- Pituitary gland, hormones of
- Pitx1
- Placenta
- [functions] [hormones] [as an allograft]
- Plague
- Planarian
- Plan B
- Plankton
- Plant
- [cells] [growth] [kingdom] [succession] [tissues]
- Plasma
- Fluid matrix of the blood. [Discussion]
- Plasma cell
- Plasma membrane
- Plasmid
- Plasmin
- Plasmodesmata
- Plasmodium falciparum
- [immune evasion]
- Plasmodium vivax
- Plasmolysis
- Plastocyanin (PC)
- Plastoquinone (PQ)
- Platelets
- [ and blood clotting ]
- Platyhelminthes (the flatworms)
- Pleiotropy
- The production by a single gene of more than one effect on the phenotype.
- Plesiomorphic
- Plumule
- Terminal bud of a plant embryo, usually consisting of embryonic leaves and the epicotyl. [Picture]
- Pluripotent stem cells
- Pneumococci (Streptococcus pneumoniae)
- [rough and smooth] [types] [genome]
- Pneumocystis jirovecii
- Poikilothermic
- Having a body temperature that fluctuates with that of the surroundings. Commonly, "cold-blooded".
- Polar body
- [genetic screening of]
- Poliovirus
- Pollination
- Polyadenylation
- Polymer
- Compound whose molecule consists of many repeated units linked together.
- Polymerase chain reaction (PCR)
- Polymorphism
- Polyol
- Polyp
- Abnormal growth of tissue that is still benign and polyclonal. Some polyps tend in time to develop a malignant clone of cells. [in colon]
- Polypeptide
- [polypeptide antibiotics]
- Polyploidy
- Polysaccharide
- Polysome
- [in protein synthesis] [picture]
- Polytene chromosomes
- Pongid
- Group of primates to which the great apes (e.g., chimpanzee, gorilla, orangutan) belong. [Evolutionary relationships]
- Pons
- Populations
- [ how regulated ] [ human ] [ cycles ]
- Porifera (the sponges)
- Porphyria, inheritance of
- Positron-emission tomography (PET)
- Post transcriptional gene silencing (PTGS)
- Postzygotic isolating mechanisms
- Potassium channels
- involvement in hereditary deafness
- Potential
- [action potential] [excitatory postsynaptic potential (EPSP)]
[inhibitory postsynaptic potential (IPSP)] [resting potential]
- PPM
- Parts per million. [More]
- Prader-Willi syndrome
- Precocenes
- Precursor
- Substance from which another substance is formed.
- Precursor activation
- Predation
- Living by devouring other organisms.
- Pregnancy
- [in humans] [hormones]
- Pre-messenger RNA (pre-mRNA)
- Prenatal Diagnosis
- Pressure-Flow theory
- Prezygotic isolating mechanisms
- Primary host
- Host normally used by a parasite during the adult stage of its life cycle.
- Primary structure (Protein)
- Primary transcript
- Primates
- Primitive
- Similar to that occurring in the early evolutionary history of the structure or organism in question.
- Primordial germ cells (PGCs)
- Prion diseases
- Producer
- An organism that can synthesize organic molecules from inorganic ones (i.e., an autotroph). Producers start food chains.
- Profundal zone
- Progeria
- Progesterone
- Progestin
- Any steroid that mimics the effects of progesterone.
- Prokaryote
- An organism whose cell contains neither a membrane-bound nucleus nor other membrane-bound organelles such as mitochondria and plastids. Includes the "true" bacteria and the archaeans. Sometimes spelled procaryote.
- Prolactin (PRL)
- Proline
- [structure] [in collagen]
- Promoter
- Region of DNA, usually on the 5' side of a gene, that is needed for the initiation of the transcription of that gene. RNA polymerase and other transcription factors bind to the promoter. [bacterial promoters] [eukaryotic promoters] [part of response element]
- Pronucleus
- The sperm nucleus and egg nucleus within the fertilized egg before their fusion to form the diploid zygote nucleus. [in humans] [making transgenic animals]
- Proopiomelanocortin (POMC)
- Prophage
- Prophase
- [in mitosis] [in meiosis I]
- Proprioception
- Prostaglandins
- [role in birth] [role in allergies]
- Prostate gland
- Prosthetic group
- The nonprotein part of a conjugated protein. Metal ions and a variety of organic molecules (e.g., vitamins, sugars, lipids) can serve as prosthetic groups. Prosthetic groups are usually bound covalently to their proteins. [More]
- Protease
- Enzyme that hydrolyzes peptide bonds whether in proteins or peptides. [serine proteases] [of HIV] [inhibitors]
- Proteasomes
- Proteinase
- Enzyme that hydrolyzes the peptide bonds of proteins.
- Protein C
- Protein chips
- Protein Kinases
- [PKA (cAMP-dependent)] [and long-term memory] [PKC (calcium-dependent)] [PKG (cGMP-dependent)]
- Proteins
- [general discussion]
[protein synthesis] [protein kinesis] [protein domains]
- Proteobacteria
- Proteoglycans
- Proteome
- Prothallus
- Prothoracicotropic hormone (PTTH)
- Protists
- Proton
- Positively charged particle found in the nuclei of all atoms. The hydrogen ion (H+) is a proton. [More]
- Protonema
- Proto-oncogene
- A normal cellular gene that, when mutated or inappropriately expressed, can cause a cell to become cancerous. Designated c-onc. They normally participate in the control of the cell cycle. [More]
- Protoplast
- A cell (plant or bacterial) from which the cell wall has been removed.
- Protostomia
- Protozoa
- Proximal
- Situated near the place of origin or attachment.
- Prozac
- Pseudoautosomal region
- Pseudocyclic photophosphorylation
- Pseudogene
-
Nonfunctional gene present in the genome of a population. Pseudogenes arise from two different mechanisms:
Pseudogenes are designated with the Greek letter psi, e.g., ΨHBBP1 is a nonfunctional version of the gene encoding the beta chain of human hemoglobin. The human genome contains some 15,000 pseudogenes.
- Psychedelic drugs
- PTTH
- Pulmonary system
- [human lungs] [their blood supply] [lungs of other vertebrates]
- Pupa
- Pupil (of human eye)
- Purines
- [analogs used as immunosuppressants]
- Pyramids of energy, biomass, and numbers
- Pyrethroids
- Pyrimidines
- PYY3-36