BIOCH200 Lecture Notes - Lecture 7: Purine, Sulfur, Cytidine
5 May 2018
School
Department
Course
Professor
Strength of bonds in Biological Molecules (Greatest to Least strength)
1. Covalent Bonds
2. Ionic Interaction
3. H-Bonds
4. Van der waals interactions → LDF is weaker than dipole-dipole
★Although Ionic interactions, H-bonds, and van der waals interactions are weaker, they are
numerous and increase in strength as the number of bonds increase.
Electronegativity of Atoms
❏Permanent dipoles are in covalent bonds where atoms have different electronegativities.
❏S-H versus O-H → S-H has a weaker dipole-dipole because oxygen has a higher affinity for
electrons → O-H has strongest dipole-dipole interaction.
Amphipathic and amphiphilic
❏Amphipathic → hydrophilic interactions and hydrophobic effect → Most of the molecule hates
water.
❏Amphiphilic → hydrophilic interactions and hydrophobic effect → Most of molecule loves water.
Introduction to Biochemistry; Nucleotides and Nucleic Acids
Protein Versus DNA
❏Protein is high in Sulfur
❏DNA is high in Phosphorus
Hershey-Chase 1952
❏Used bacteriophages to prove that DNA is genetic material.
❏Infection → Blending → Centrifugation.
Nucleotides are involved in;
1. Oxidation-Reduction
2. Energy transfer
3. Intracellular signalling
4. Biosynthetic reactions
5. Storage and decoding genetic information
Nucleotides
❏Include nucleic acids → Deoxyribonucleic acid (DNA) or Ribonucleic Acid (RNA)
❏High energy molecules → NTP’s contain a “high energy” covalent bond
❏Some molecules are electron carriers.
❏Nucleotides are composed of Phosphates nucleotides and a Nitrogen containing base.
Purine and Pyrimidine Bases
❏All bases are aromatic (sharing of electrons) and heterocyclic (more than 1 major atom)
Lone pairs in resonance are incapable of accepting hydrogen bonds
Hydrogen bonding of the bases
❏Pyrimidine Derivative → 2 H-bond Acceptors
❏Uracil → 4 accepters, 2 donors
❏Thymine → 4 acceptors, 2 donors
❏Cytosine → 3 acceptors, 2 donors
❏Purine derivative → 3 acceptor, 1 donor
❏Adenine → 3 acceptor, 3 donor
❏Guanine → 4 donor, 4 acceptors.
Document Summary
Strength of bonds in biological molecules (greatest to least strength: covalent bonds. Ionic interaction: h-bonds, van der waals interactions ldf is weaker than dipole-dipole. Although ionic interactions, h-bonds, and van der waals interactions are weaker, they are numerous and increase in strength as the number of bonds increase. Permanent dipoles are in covalent bonds where atoms have different electronegativities. S-h versus o-h s-h has a weaker dipole-dipole because oxygen has a higher affinity for electrons o-h has strongest dipole-dipole interaction. Amphipathic hydrophilic interactions and hydrophobic effect most of the molecule hates. Amphiphilic hydrophilic interactions and hydrophobic effect most of molecule loves water. Used bacteriophages to prove that dna is genetic material. Nucleotides are involved in: oxidation-reduction, energy transfer. Intracellular signalling: biosynthetic reactions, storage and decoding genetic information. Include nucleic acids deoxyribonucleic acid (dna) or ribonucleic acid (rna) High energy molecules ntp"s contain a high energy covalent bond. Nucleotides are composed of phosphates nucleotides and a nitrogen containing base.
