Living Environment Notes 05/15/2023

  • PCR is a tool used to amplify DNA(creates a bunch of copies of DNA to study a specific sequence of the DNA)

    • Uses a polymerase enzyme to mimic DNA replication
    • Three main steps to the process(process happens in vitro-outside the cell):
    • Denaturation: Sample is heated to break hydrogen bonds holding together DNA
    • Annealing: Sample is cooled down and primers are stuck to DNA strands
    • Extension: Sample is heated and DNA polymerase binds to the primer and synthesizes a new DNA strand(new DNA strand is created and process ends)
    • To calculate the number of target DNA strands produced, simply raise 2 to the power of the amount of cycles that are occurring
    • PCR applications: Medical diagnostics, Tissue typing, Prenatal screening, Forensic samples, Serotyping, DNA extraction from fossils, phylogeny

  • Gel electrophoresis: A tool used to separate fragments of DNA according to size and charge when provided with a DNA strand or sequence

    • Visualizes DNA profiles using a banding pattern in gel, caused by the difference in size of DNA particles
    • You could compare the DNA profile to compare DNA of individuals or see if the DNA from one area matches the DNA of a person in order to find the suspect of victim of a crime
    • Gel electrophoresis works because DNA has a negative charge
    • DNA strands are placed in a gel and then placed in a water buffer which electricity is run through(once electricity is run through all the particles of DNA start racing to the positive charge since negative charge tends to go towards positive charge)
    • Larger particles will not be able to move down the water buffer as quickly, whereas the smaller particles will be able to move quickly towards the positively charged anode
    • This process only works because DNA strand is cut up into smaller pieces, this cutting process is thanks to the restriction enzymes

Genome editing: The ability to change an organism’s DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome.

  • Bioengineered crops: Plants with one or more genetic characteristics that were inserted into the genome using biotechnology
  • Similarities between normal crops and bioengineered crops: desired traits can be identified and perpetuated, life cycle and growth of plant is equivalent, safety and nutrition of plant is equal, main difference is the benefits that come from inserting a gene into the bio-engineered plant(may be resistant to pests, have a longer shelf life, etc.)
  • There are many government corporations such as the FDA that are required to ensure that the production of biogenetically engineered crops are ethical, and fit the same health and nutrition standards as normal crops, as well as ensuring that the changing of a crops genetic materials will not influence any living organisms around it

Artificial Breeding: Creating new breeds of animals and new crop plants to improve our food

  • Code for DNA is universal: all living organisms use the same DNA, use the same code book, and read their genes the same way. This allows for DNA analysis and comparison, as well as genome editing, because if a gene sequence is added or removed from the entire DNA strand, the DNA will just fuse the gap of DNA missing and begin to read and replicate the new DNA the same way it did prior to the transformation
  • Genes can be mixed for a variety of purposes including medicine(bacteria producing human insulin, bacteria producing human growth hormone)

Steps of genetic engineering(mixing genes):

  • find gene, cut DNA in both organisms, paste gene from one creature into other creature’s DNA, insert new chromosome into organism, organism copies new gene as if it were its own, organism reads gene as if it were its own, organism produces new protein during replication containing the new genetic material
  • The process of cutting DNA is only possible due to things called restriction enzymes. These enzymes act as a scissor, chopping up segments of DNA to allow for genome editing. This is possible due to the enzymes using of bacteria to look for specific base sequences that will be removed.
  • After a restriction enzyme cuts a DNA segment out of the original strand, there are “sticky ends” left, which refers to the gap in DNA left by the removal of genetic material at a certain position in the strand. This leads to DNA being glued together to rectify the missing material.
  • Genes are mixed together in order to produce proteins in different organisms or different individuals
  • Genetic Engineering, as mentioned earlier, can be used to modify crops, which are called GMO’s or genetically modified organisms. These GMO’S enable plants to produce new proteins which will protect the crops from insects, extend growing seasons, and improve the quality of foods(primarily through adding in vitamins)

Further analyzation of the genetic engineering process:

  • Plasmids: small extra circles of DNA in a bacteria which carry extra genes the bacteria can use
  • Plasmids allow for scientists to put genes into bacteria easily, as the new gene is inserted into the plasmid with the help of a restriction enzyme, the plasmid is inserted back into the bacteria, and the bacteria now expresses the new gene
  • When the bacteria replications via mitosis, there will be multiple copies of the new bacteria with the new gene, which can be later harvested to create hormones(such as human insulin or human growth hormone)

Cloning: to create a identical copy of something(clone)

  • a member of a genetically identical organism is produced by a single cell
  • DNA can be cloned via genetic engineering
  • Take the nucleus from a somatic cell of a white sheep(somatic cell donor)
  • Take an egg cell from a black sheep and take the nucleus out(egg donor cell)
  • Fuse the nucleus and the egg cell
  • Grow the cells
  • Insert the cells in the uterus of a surrogate mother
  • She will give birth to a lamb that will be genetically identical to the white sheep