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Chapter 4 Nucleic Acids “The Flow of GeneticInformation in the Cell”
Nucleic AcidsPolymers specialized for the storage,transmission, and use of geneticinformation.DNA = deoxyribonucleic acidRNA = ribonucleic acidThe monomeric units (building blocksof nucleic acids) are nucleotides.
NucleotidesConsist of apentose sugar, aphosphate group,and a nitrogen-containing base.
Nitrogenous BasesDNA bases: adenine (A),cytosine (C), guanine (G),and thymine (T)Complementary basepairing: A–T(U) C–GPurines pair withpyrimidines by hydrogenbonding.Instead of thymine, RNAuses the base uracil (U).
Nucleic Acid SynthesisThe “backbone” of DNAand RNA is a chain ofsugars and phosphategroups, bonded byphosphodiester linkages.
Nucleic Acid Synthesis• The two strands of DNA run in opposite directions (antiparallel).
DNAThe two strands of a DNA molecule form a double helix. (anti-parallel)All DNA molecules have the same structure; diversity lies in the sequence of base pairs.
RNASingle StrandedLess Stable then DNAWhat clue does thisgive us to its functionin comparison toDNA?
“The Correct Flow of Genetic Information in the Cell” Central Dogma of Molecular BiologyThe complete set of Not all the informationDNA in a living is needed at all times;organism is called its sequences of DNAgenome. that encode specific proteins are called genes.