Nucleic Acid

• DNA


  Genetic storage molecule that indirectly codes for proteins
• Central dogma of molecular biology

  1. DNA serves as a template for the direct synthesis of mRNA

  2. mRNA is read at a ribosome by tRNAs to assemble a specific chain of amino acids which collectively assembled to generate a protein
• DNA


  Directly creates all of the intermediate players of transcription and translation
• Transcription


  The process where DNA directly creates mRNA
• Translation


  The process where mRNA is read by the ribosome and translated into a specific sequence of amino acids to form a protein
• Nucleotides


  The monomers that make up nucleic acids (DNA and RNA)
• Deoxyribonucleotides


  The monomers that make up DNA, composed of a phosphate group, deoxyribose sugar, and one of four nitrogenous bases (adenine, thymine, cytosine, guanine)
• Ribonucleotides


  The monomers that make up RNA, composed of a phosphate group, ribose sugar, and one of four nitrogenous bases (adenine, uracil, cytosine, guanine)
• Phosphodiester bond


  The covalent bond that forms between the 3' carbon of one nucleotide's sugar and the phosphate group of an adjacent nucleotide, linking nucleotides together in a nucleic acid
• 5' end


  The end of a nucleic acid strand that has a phosphate group
• 3' end


  The end of a nucleic acid strand that has a sugar
• Primary structure of nucleic acids

  The sequence of nucleotides in a nucleic acid, written from 5' to 3' end
• RNA


  A single-stranded nucleic acid composed of ribonucleotides, responsible for actively synthesizing proteins
• mRNA


  Messenger RNA, which transmits genetic information from DNA to the ribosome
• rRNA


  Ribosomal RNA, a component of the ribosome
• tRNA


  Transfer RNA, reads the mRNA and links specific amino acids to the growing protein chain
• Chargaff's rules


  The relative abundance of guanine equals cytosine, and the relative abundance of adenine equals thymine, across different organisms
• DNA secondary structure


  The double-stranded, anti-parallel, helical structure of DNA, with base pairing between adenine-thymine and guanine-cytosine
• DNA secondary structure


  • Consistent width
  • Repeating pattern
  • Helical shape
• Watson and Crick used Chargaff's rules and measurements from X-ray crystallography to determine the double-helix structure of DNA
• DNA


  Composed of two strands, one running 5' to 3' connected to a second strand running 3' to 5', this orientation is called anti-parallel
• Base pairing


  The nitrogenous bases from adjacent DNA strands connect according to base pairing, as determined by Watson and Crick
• The consistent width of the DNA supported the A-T and C-G base pairing
• Hydrogen bonding


  The partially positive hydrogens of the nitrogenous bases are attracted to the partially negative oxygens and nitrogens, forming hydrogen bonds
• Proteins


  Biological molecules that serve as cellular machines and are involved in various biological processes
• Amino acids


  The monomers that make up proteins, consisting of a central carbon atom, a hydrogen atom, an amine group, a carboxyl group, and a side chain (R group)
• Peptide bond


  The covalent bond formed between the carboxyl group of one amino acid and the amine group of another, resulting in the formation of a polypeptide chain
• Protein structure


  • Primary structure: the unique amino acid sequence
  • Secondary structure: the regular patterns formed by hydrogen bonding between neighboring amino acids, such as alpha helices and beta pleated sheets
  • Tertiary structure: the specific folding patterns of the polypeptide chain determined by interactions between R groups
  • Quaternary structure: the overall structure of a protein composed of multiple polypeptides
• Sickle-cell anemia is caused by a single amino acid substitution in the hemoglobin protein, resulting in sickle-shaped red blood cells
• Sickle-cell anemia provides an evolutionary advantage in malaria-endemic regions, as the sickle-shaped cells are less susceptible to the malaria parasite
• Primary structure of nucleic acids

  The order of bases in the polynucleotide sequence
• Secondary structure of nucleic acids

  The three-dimensional conformation of the backbone
• Tertiary structure of nucleic acids

  The supercoiling of the molecule
• Types of nucleic acids

  • DNA (deoxyribonucleic acid)
  • RNA (ribonucleic acid)
• Differences between DNA and RNA appear in their secondary and tertiary structures
• Components of a nucleotide

  Nitrogenous base, sugar, phosphoric acid residue
• Polymerization of nucleotides


  1. Forms nucleic acids

  2. Involves 3',5'-phosphodiester bonds
• The order of bases in DNA contains the information to produce the correct sequence of bases in RNA and amino acids in proteins
• Pyrimidine bases


  • Cytosine
  • Thymine
  • Uracil
• Purine bases


  • Adenine
  • Guanine