Using Genetics 3/4

• DNA sequencing


  Determining the exact order of bases that make up a strand of DNA (segment of DNA eg. segment coding for hair)
• Sequenced data


  • Can highlight changes in a gene (mutation) that may cause disease
  • Used for genetic screening
• Genetic screening


  Used to prevent the onset of diseases for early detection and treatment
• Chromatograms


  Sequencing machines
• DNA base


  • Represented as a peak of a different colour
  • Adenine (green)
  • Cytosine (blue)
  • Guanine (black)
  • Thymine (red)
• DNA marker


  A gene or DNA sequence with a known location on a chromosome
• Gel Electrophoresis


  1. Used to separate molecules based on size, in this case DNA

  2. DNA is added into vial containing restriction enzymes that will cut the DNA at specific restriction sites

  3. DNA has a negative charge (from phosphate), when the electrical current is applied to the gel making it positively charged the DNA will begin to travel through the gel towards the positive end

  4. Longer DNA fragments have a higher molecular weight causing them to move slower through the gel

  5. Shorter DNA fragments have lower molecular weight causing them to move faster through the gel
• DNA fingerprinting


  Comparing DNA bands to other bands from suspects in crime scenes to determine who was the criminal
• How to produce a DNA fingerprint

  1. Isolation - separate the DNA from other tissues

  2. Fragmentation - use an enzyme to break the DNA into short lengths

  3. Separation - pass an electric current across a layer of gel which has the DNA fragments at one end, the fragments will move different distances across the gel

  4. Comparison - match the pattern of fragments on the gel with other samples of DNA
• DNA profiling


  A method used to determine an individual or organism's DNA characteristics
• Approximately 99.9% of DNA sequences are the same in all humans. The remaining variable DNA is enough to identify an individual.
• DNA barcoding


  • A method used to identify species based on the base sequence of the genetic marker
  • Members of the same species have the same base sequences meaning they have the same DNA barcode
  • Species closely related will have similar but not the exact same DNA barcode
  • Species that are not closely related will not have similar DNA barcodes
• eDNA


  • DNA found within an environment, living organisms will shed genetic material such as skin cells, hair, fur, scales and feces
  • eDNA does not allow us to determine how many individuals of a species are present, only the type
• Phylogenetic trees


  • Diagram that represents the relatedness of organisms, reflecting their evolutionary history
  • The horizontal line represents time, left is ancestors to right is present day species
  • The vertical line represents when species separated from their common ancestor
• mtDNA


  • Mitochondrial DNA, inherited entirely from the mother and not mixed up with the fathers DNA during fertilisation
  • mtDNA is much easier to track as there is no recombination, and is easier to extract compared to nuclear DNA
• The egg of a female human contains lots of mitochondria, while male sperm only contains a little mitochondria. When sperm fertilizes the egg the mitochondria is destroyed, thus any mtDNA that could be passed from the fathers side is lost.
• Genome


  The entire set of DNA instructions found in a cell, the full amount of genetic information that an organism carries in its DNA
• Understanding Human Health


  • Lead to the development of improved diagnostic tools, targeted therapies, and personalized medicine
  • Can help identify individuals who may be at higher risk for certain genetic disorders, allowing for early interventions or preventive measures
• Advancing Medical Research


  • Genomic research provides a foundation for advancing medical knowledge and scientific understanding
• Precision Medicine


  • Each person's genome is unique, and understanding individual genetic variations can help tailor medical treatments to individual needs
• Evolutionary Studies


  • The genome provides a wealth of information about the evolutionary history of species
  • By comparing genomes across different organisms, researchers can study genetic similarities and differences, uncover evolutionary relationships, and trace the origins of species
• More than 98 percent of our genome is noncoding DNA—DNA that doesn't contain information to make proteins.
• All humans have the same genes arranged in the same order. And more than 99.9% of our DNA sequence is the same. But the few differences between us (all 1.4 million of them!) are enough to make each one of us unique. On average, a human gene will have 1-3 bases that differ from person to person. These differences can change the shape and function of a protein, or they can change how much protein is made, when it's made, or where it's made.