genbio ver..2

• Friedrich Miescher (1844–1895) - isolated the material “nuclein” when studying pus cells from surgical bandages.
• Nucleotides - Nucleotides are 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 - Nucleic acids are 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.
• STRUCTURE OF DNA

  nitrogenous base

  pentose sugar

  
  

  deoxyribose

  ribose

  
  

  phosphate group
• Ribose - sugar in RNA
• deoxyribose - deoxygenated sugar present in DNA.
• glycosidic bond – connects the pentose sugar to the nitrogenous base
• Polypeptide chain – chain of the nucleotides showing sequences of nitrogenous bases
• phosphoester bond – connects phosphate group to the pentose sugar
• Purines – 2 rings, ex. Guanine Adenine (PuGA)

  Pyrimidine – 1 ring, ex. Cytosine, Thymine, Uracil (PyCTU)
• • DNA Helix the twisted ladder-like structure of the two strands of DNA
• • Nucleoside the complex of a sugar and a base. Four types are present in DNA.
• The cyclic bases are classified to purines and pyrimidines.
• The two strands of DNA are said to be antiparallel.

  Meaning, the direction of the strands of the DNA are going in opposite directions.
• Rosalind Franklin and Maurice Wilkins -performed x-ray crystallography technique to analyze the structure of DNA.
• RNA - is known to be single-stranded,
• RNA -       have the base uracil instead of thymine in DNA
• -       Amino acids are the subunits or monomers of proteins.
• RNA -       have ribose instead of deoxyribose in DNA,
• RNA -       a product of transcription of DNA
• CENTRAL DOGMA OF MOLECULAR BIOLOGY

  -       It describes the flow of genetic information from DNA to RNA to Proteins
• Primary structure

  Amino Acid to Amino Acid (Polypeptides)

  Forms peptide bond
• Protein Data Bank (PDB)

  PDB is an enormous collection of published experiments on the structure of DNA, RNA and proteins.
• Secondary structure

  May be in the form of a helix or a pleated sheet. Forms hydrogen bond.
• Tertiary structure

  3D structure

  Stabilized by covalent and weak non-covalent interactions.
• Quaternary structure

  When multiple folded protein subunits form a single complex

  Requires more complex molecular interactions
• Steps in Replication

  Initiation, Elongation, Termination
• Replication

  DNA Replication is semi-conservative.

  Meaning,

  Each newly synthesized molecule contains 1 “parent template” strand and 1 new “daughter” strand
• Replication

  Step 1: Initiation

  Helicase unwinds DNA forming a “replication fork”

  Multiple replication forks along a DNA molecule create replication bubbles
• Replication

  Elongation
• RNA Primase

  Adds a complimentary RNA primer to each template strand as a starting point for replication
• DNA Polymerase

  Reads the template strand (3' to 5') and adds new complimentary nucleotides (5' to 3')
• DNA synthesized

  • Leading strand (in the or towards the direction of the replication fork)
  • Lagging strand (the one moving away from the replication fork)
• The polymerases synthesize DNA in the 5' to 3' direction
• Leading strand


  • Replicates continuously
• Lagging strand


  • Replicated discontinuously
• Okazaki fragment


  The segment of DNA produced in lagging strand