nucleotides and nucleic acids

• Communicable diseases are caused by common pathogens and can be prevented through transmission control measures.
• Plant defenses against pathogens include physical barriers, chemical defenses, and biological control.
• Non-specific immune responses include phagocytes, blood cells, the T lymphocyte response, the B lymphocyte response, primary and secondary immune responses, antibodies, opsonins, agglutinins, and anti-toxins.
• Types of immunity include innate immunity, active immunity, and passive immunity.
• Autoimmune diseases are conditions where the immune system attacks the body's own tissues.
• Principles of vaccination include the selection of the right antigen, the choice of delivery method, and the timing of administration.
• Sources of medicine include traditional medicine, herbal medicine, and modern medicine.
• Antibiotics are a type of medicine used to treat bacterial infections.
• Conservation agreements are methods of maintaining biodiversity.
• The binomial system is a classification system for species.
• The classification of the three domains is a system for classifying species.
• The classification of the five kingdoms is a system for classifying species.
• The phylogeny of species is a system for classifying species.
• DNA and RNA are nucleic acids: polymers that are made up of many repeating units (monomers) called nucleotides.
• Each nucleotide is formed from a pentose sugar (a sugar with 5 carbon atoms), a nitrogen-containing organic base, and a phosphate group.
• DNA nucleotides contain a deoxyribose sugar with hydrogen at the 2' position, a phosphate group, and one of four nitrogenous bases: adenine (A), cytosine (C), guanine (G) or thymine (T).
• RNA nucleotides contain a ribose sugar with a hydroxyl (OH) group at the 2' position, a phosphate group, and one of four nitrogenous bases: adenine (A), cytosine (C), guanine (G) or uracil (U).
• The presence of the 2' hydroxyl group makes RNA more susceptible to hydrolysis, which is why DNA is the storage molecule and RNA is the transport molecule with a shorter molecular lifespan.
• Purines and pyrimidines are the nitrogenous base molecules that are found in the nucleotides of DNA (A, T, C, G) and RNA (A, U, C, G).
• Purines, such as adenine and guanine, have a double ring structure, while pyrimidines, such as cytosine, thymine and uracil, have a single ring structure.
• DNA and RNA are polymers (polynucleotides), meaning that they are made up of many nucleotides joined together in long chains.
• Separate nucleotides are joined together via condensation reactions.
• A condensation reaction between two nucleotides forms a phosphodiester bond.
• The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as the sugar-phosphate backbone (of the DNA or RNA molecule).
• In condensation reactions, a molecule of water is released, while in hydrolysis reactions, a molecule of water is added.