biology

• Nucleic Acids


  Composed of nucleotides
• Nucleotides


  • Monomers of Nucleic acids
  • Components of other molecules (ATP, GTP etc)
• Components of nucleotides

  • Pentose sugar: Ribose or deoxyribose
  • Phosphate
  • Nitrogenous base: Adenine (A), Thymine (T), Guanine (G), Cytosine (C) or Uracil (U)
• Nucleoside

  Pretty much the same thing as a nucleotide but it does not have the phosphate
• Types of nucleic acids

  • DNA (deoxyribonucleic acid)
  • RNA (ribonucleic acid)
• DNA

  Deoxyribonucleic acid, a nucleic acid arranged in a double helix with two strands
• DNA

  • Template (antisense) strand: 3'-5'
  • Coding (sense) strand: 5'-3'
• DNA nucleotides composed of

  • Deoxyribose
  • Phosphate
  • Nitrogenous bases A, T, C and G
• Polymerization


  Performed by DNA polymerase (an enzyme)
• Phosphodiester linkages


  Linkages between nucleotides in the DNA backbone
• Hydrogen bonds


  Bonds linking the double helix together between nitrogenous bases: 2 hydrogen bonds: A-T and A-U, 3 hydrogen bonds: C-G
• Location of DNA in eukaryotic cells

  • Nucleus
  • Mitochondrial Matrix
  • Chloroplast Stroma
• Location of DNA in prokaryotic cells


  Cytosol
• Chargaff's rules


  States that in the DNA of any species and organism, the amount of guanine should be equal to the amount of cytosine and the amount of adenine should be equal to the amount of thymine. As well as this, a 1:1 stoichiometric ratio of purine and pyrimidine bases should exist.
• Nitrogenous Bases

  Organic compounds that contain nitrogen and are found in nucleic acids
• Families of nitrogenous bases

  • Purines (2 rings)
  • Pyrimidines (1 ring)
• Purines


  • A
  • G
• Pyrimidines

  • C
  • T
  • U
• Pyrimidine


  Binds to purine with hydrogen bonds
• A binds to T

  2 H-bonds
• A binds to U

  2 H-bonds
• C binds to G

  3 H-bonds
• RNA


  Ribonucleic acid is a single stranded polymer consisting of a Ribose (pentose sugar), Phosphate, and A, U, C, or G
• Types of RNA

  • mRNA (messenger RNA)
  • tRNA (transfer RNA)
  • rRNA (ribosomal RNA)
  • Other RNA's (ncRNA, miRNA, etc)
• mRNA (messenger RNA)


  • Used in protein synthesis
  • Synthesized with RNA polymerase II
• tRNA (transfer RNA)


  • Used to transport amino acids for translation
  • Synthesized with RNA polymerase III
• rRNA (ribosomal RNA)


  • Component of ribosomes
  • Synthesized with RNA polymerase I
• Water

  Is a good solvent: can dissolve molecules
• Water

  • Is less dense in solid form (Ice) than in liquid form
  • Allows for aquatic life
• Water

  • Has high heat capacity: makes it hard to heat up
  • Due to hydrogen bonds requiring more energy to break
  • Allows life to withstand changes in temperature
• Biological reactions

  Take place in water -> Many reactions need the reagents to be in aqueous solution
• Water molecules

  • Cohesion: allows water to stick together
  • Important for water to move upwards in plants
• Specific heat capacity

  Amount of heat needed to raise 1g of a substance's temperature by 1 degree Celsius
• Water

  • Has a high specific heat capacity
  • Relevant in terms of being able to withstand temperature change
• Latent heat of vaporization

  The amount of heat that must be transferred to a liquid substance (at its boiling point) to turn it into a gas
• Water

  • Has a high heat of vaporization
  • Relevant in terms of sweating: we need it to cool down
• Eukaryotes

  • Have organelles
  • Replicate by Mitosis/Meiosis
  • Have both linear (in nucleus) and circular (in mitochondria and chloroplast) DNA
  • Are roughly between 1-100um (some can get a lot larger however)
  • Have histones and chromatin
  • Have the Na+/K+ pump
  • Use the Krebs cycle, electron transport chain in cellular respiration
• Prokaryotes

  • Have no membrane bound organelles
  • Replicate via binary fission
  • Have circular DNA
  • Are roughly between 0.2-2um
  • Have nucleoid proteins
  • Have the H+ Pump (proton pump)
  • Can have capsules
• Similarities Between Eukaryotes and Prokaryotes

  • Have ribosomes
  • Have a cytoplasm
  • Have a plasma membrane
  • Have DNA/RNA
  • Can have Flagella
  • Have a cytoskeleton
  • Can have a cell wall
  • Perform glycolysis
• Eukaryotes

  • Have ribosomes (80s + 70s)
  • Plants: cell wall made from cellulose
  • Fungi: cell wall made from chitin