Nucleotides and Nucleic Acids

• Each nucleotide consists of a pentose sugar, a nitrogen-containing organic base, and a phosphate group
• Nucleotides are phosphate esters of pentose sugars, with the nitrogenous base linked to the C₁ of the pentose sugar, and the phosphate group linked to the C₅ or C₃
• DNA and RNA are nucleic acids made of nucleotides
• In RNA, the pentose sugar is ribose, while in DNA, the pentose sugar is deoxyribose
• Nucleotides become phosphorylated nucleotides when they contain more than one phosphate group, like ADP and ATP
• Nucleotides help regulate metabolic pathways, such as ATP, ADP, and AMP
• Nucleotides may be components of coenzymes
• DNA is a macromolecule found in the nuclei of eukaryotic cells and the cytoplasm of prokaryotic cells
• DNA carries coded instructions used in the development and functioning of living organisms
• DNA is a polymer made of repeating monomeric units called nucleotides
• DNA consists of two polynucleotide strands that are antiparallel
• Each nucleotide in DNA consists of a phosphate group, deoxyribose sugar, and one of four nitrogen bases: adenine, guanine, thymine, cytosine
• DNA strands are joined by hydrogen bonds between nitrogen bases, pairing via complementary base pairing
• Purines always pair with pyrimidines, allowing DNA to twist into a double helix coil for stability
• DNA replication is semi-conservative, resulting in two identical DNA molecules with one old and one new strand
• Errors during DNA replication can lead to mutations, which can be proofread and edited by enzymes
• RNA has ribose as the sugar molecule, uracil as a nitrogenous base, and is usually single-stranded
• There are three forms of RNA: messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)
• Genes on chromosomes contain DNA base triplets that determine the amino acid sequence in proteins
• Genes are transcribed into mRNA, which carries the instructions to ribosomes for protein synthesis
• The genetic code is universal, degenerate, and non-overlapping
• Transcription involves unwinding and unzipping DNA, RNA polymerase catalyzing RNA formation, and mRNA passing out of the nucleus
• Translation involves tRNA bringing amino acids to ribosomes, forming peptide bonds between amino acids, and using ATP for polypeptide synthesis
• After polypeptide synthesis, mRNA breaks down and can be recycled