genbio2

• Friedrich Miescher isolated the material "nuclein" when studying pus cells from surgical bandages


  1844–1895
• Nucleotides

  The basic units of DNA, composed of a phosphate group (P), a sugar (deoxyribose), and a nitrogenous base (A, C, G, or T) that encodes genetic information

  
• Nucleic Acid

  The main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing
• Nucleic Acids

  • Deoxyribonucleic Acid (DNA)
  • Ribonucleic Acid (RNA)
• DNA structure

  • Nitrogenous base
  • Pentose sugar (Deoxyribose in DNA, Ribose in RNA)
  • Phosphate group
  • Glycosidic bond (connects sugar and base)
  • Phosphoester bond (connects phosphate and sugar)
• Nucleoside


  The complex of a sugar and a base. Four types are present in DNA.

  
• Polypeptide chain


  Chain of the nucleotides showing sequences of nitrogenous bases

  
• Purines

  2 rings, e.g. Guanine, Adenine
• Pyrimidines

  1 ring, e.g. Cytosine, Thymine, Uracil

  
• DNA Helix

  • Twisted ladder-like structure of the two strands of DNA
  • The two strands are antiparallel (going in opposite directions)
• Rosalind Franklin and Maurice Wilkins performed x-ray crystallography technique to analyze the structure of DNA
• RNA

  • Single-stranded
  • Has the base uracil instead of thymine in DNA
  • Has ribose instead of deoxyribose in DNA
  • A product of transcription of DNA
• Amino Acids


  The subunits or monomers of proteins
• Levels of Protein Structure

  • Primary (Amino Acid to Amino Acid, Polypeptides, Peptide bond)
  • Secondary (Helix or pleated sheet, Hydrogen bond)
  • Tertiary (3D structure, Covalent and weak non-covalent interactions)
  • Quaternary (Multiple folded protein subunits forming a single complex, More complex molecular interactions)
• Protein Data Bank (PDB) is an enormous collection of published experiments on the structure of DNA, RNA and proteins
• Differences between DNA and RNA

  • DNA is double-stranded, RNA is single-stranded
  • DNA uses the base Thymine, RNA uses the base Uracil
  • DNA uses the sugar Deoxyribose, RNA uses the sugar Ribose

  
• Central Dogma of Molecular Biology


  It describes the flow of genetic information from DNA to RNA to Proteins

  
• DNA Replication

  1. Initiation (Helicase unwinds DNA, Replication forks and bubbles)

  2. Elongation (RNA Primase adds complementary RNA primer, DNA Polymerase reads template and adds new nucleotides, Leading and Lagging strands)

  3. Termination (DNA Polymerase removes RNA primer, DNA Ligase joins Okazaki fragments, Helicase rewinds DNA)
• Types of RNA

  • mRNA (Messenger RNA, Encodes amino acid sequence)
  • tRNA (Transfer RNA, Brings amino acids to ribosomes)
  • rRNA (Ribosomal RNA, With ribosomal proteins, makes up ribosomes)
  • snRNA (Small nuclear RNA, With proteins, used in RNA processing)
• Transcription (RNA Synthesis)

  1. Initiation (RNA Polymerase binds to promoter, TATA box)

  2. Elongation (RNA Polymerase moves along gene, adds new RNA nucleotides)

  3. Termination (RNA Polymerase reaches terminator region, all enzymes and factors released)
• Translation (Protein Synthesis)

  1. Initiation (mRNA 5' G-cap binds ribosome, Start codon AUG and anticodon with Methionine bind P site, Next tRNA enters A site)

  2. Elongation (Codon recognition, Peptide bond formation, Translocation)

  3. Termination (Stop codon reached, all parts release)
• When translating an mRNA sequence, identify the location of the start codon AUG, divide the succeeding sequence into segments of three nucleotides until a stop codon is reached

  
• Application: Replication

  • Check the Parent (Template) Strand
  • Get the complementary strand using the template strand
• Application: Transcription

  • Transcribe the complementary strand to get the mRNA sequence
• Application: Translation

  • Find the AUG start codon, form the codons, translate into amino acids