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• There are three molecules at the heart of genetics; DNA, RNA, and Proteins. DNA and RNA are two types of Nucleic Acids. Protein is considered as a very important biomolecule in our body because it really helps in the development of our body.
• The most remarkable property of living cells is their ability to produce or come up with the exact replicas of themselves.
• In the Gene, we could see the basic substances responsible for the different activities for the different information that are passed on from generations to generations.
• According to studies, in the next 60 seconds your body will produce enough new DNA that if it was linked together, it would stretch 100,000 km.
• Nobel Prize in Physiology and Medicine

  1962
• Nucleic Acid


  Discovered by Friedrich Miescher around 1869 while studying the nuclei of the RBC
• Rosalind Franklin took diffraction x-ray photographs of DNA crystals.
• In the 1950's, Watson & Crick built the first model of DNA using Franklin's x-rays.
• Watson & Crick: '"It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."'
• Central Dogma of Biology

  Refers to the different processes specially in the process of protein synthesis. We have the Replication, Transcription, Translation.
• Importance of Central Dogma to modern biology

  • Without this process, reproduction of species would not occur as genetic information would not be able to stored and produce proteins which are essential in biochemical processes.
• DNA (Deoxyribonucleic Acid)


  • DNA directs the machinery of a cell to make specific proteins, and, therefore, DNA indirectly controls all of the functioning of all living things.
  • DNA stores the hereditary information of an individual.
  • DNA has the ability to mutate (change).
  • It allows a new characteristics and abilities to appear that helps survive and produce a living organism (evolution).
• DNA


  A nucleotide polymer in which each of the monomers contains deoxyribose, a phosphate and one other heterocyclic base (Adenine, Cytosine, Guanine and the Thymine).
• DNA has the ability to make copies of itself.
• Double Helix


  • Most DNA has a right-hand twist with 10 base pairs in a complete turn.
  • Left twisted DNA is called Z-DNA or southpaw DNA
  • Hot spots occur where right and left twisted DNA meet producing mutations.
• Nucleotide


  Made of: 1. Phosphate group 2. 5-carbon sugar 3. Nitrogenous base
• Antiparallel Strands


  • One strand of DNA goes from 5' to 3' (sugars)
  • The other strand is opposite in direction going 3' to 5' (sugars)
• DNA Structure


  • DNA is composed of four nucleotides, each containing: adenine, cytosine, thymine, or guanine.
  • The amounts of A = T, G = C and purines = pyrimidines (Chargaff's Rule)
  • DNA is a double - stranded helix with antiparallel strands (Watson and Crick).
  • Uracil present in the RNA but not in the DNA. Uracil usually replaces the Thymine in the RNA structure.
  • Erwin Chargaff showed the amounts of the four bases on DNA (A, T, C, G)
• In a body or somatic cell: A = 30.3%, T = 30.3%, G = 19.9%, C = 19.9%
• Chargaff's Rule


  • Adenine must pair with Thymine
  • Guanine must pair with Cytosine
  • The bases form weak hydrogen bond
  • Nucleotides in each strand are linked by 5' - 3' phosphodiester bonds
  • Bases on opposite strands are linked by hydrogen bonding: A with T and G with C
• Pyrimidine


  A monocyclic base with a six -membered ring (thymine, cytosine and uracil)
• Purine


  Bicyclic base with fused five and six-membered ring (adenine and guanine)
• If there is 30% Adenine, there would be 20% Cytosine. Adenine (30%) = Thymine (30%), Guanine (20%) = Cytosine (20%), Therefore, 60% A-T and 40% C-G
• If a piece of double stranded DNA has a guanine content of 26%, the proportion of thymine expected is 24%
• DNA Replication

  The purpose of DNA replication is to produce two identical copies of a DNA molecule. This is essential for cell division during growth or repair of damaged tissues. DNA replication ensures that each new cell receives its own copy of the DNA.
• Replication happens on the Interphase.
• The process by which new DNA molecules are generated is what we call as DNA replication.
• It is a biochemical process by which DNA molecules produces exact duplicates/copies of themselves.
• DNA Replication Facts


  • In human cells, 50 nucleotides are added every second to a new strand of DNA.
  • The Replication process takes about 8 hours in human cells.
  • DNA polymerase has a built in "proof-reading" functions to correct errors.
  • Errors are limited to 1 error / billion nucleotide.
  • DNA has to be copied before a cell divide.
  • DNA is copied during the S or synthesis phase of Interphase.
  • New cells will need identical DNA strands.
• Accuracy and Repair


  DNA copied with a high degree of accuracy
• Mutation


  Change in the nucleotide sequence of DNA; it can have a serious effect on organism, can be harmful or beneficial
• Environmental factors can damage the DNA. Example: Ultraviolet radiation of the SUN.
• DNA Ligase


  The enzyme that catalyzes the joining of DNA fragments together
• DNA Polymerase


  An enzyme that synthesizes a new strand of DNA complementary to a template strand
• Helicase


  An enzyme that helps to open up the DNA helix during DNA replication by breaking the hydrogen bonds
• Lagging Strand


  During replication of the 3' to 5' strand, the strand that is replicated in short fragments and away from the replication fork
• Leading Strand


  The strand that is synthesized continuously in the to 3 direction that is synthesized in the direction of the replication fork
• Mismatch Repair


  A form of DNA repair in which non-complementary nucleotides are recognized, excised, and replaced with correct nucleotide
• Mutation


  A permanent variation in the nucleotide sequence of a genome
• Nucleotide Excision Repair


  A form of DNA repair in which the DNA molecule is unwound and separated in the region of the nucleotide damage, the damaged nucleotides are removed and replaced with new nucleotides using the complementary strand and the DNA strand is resealed and allowed to rejoin its complement