Dna and Biotech

• Nucleotides


  Subunits of DNA and RNA, consisting of a sugar, a phosphate, and one nitrogenous base
• Nitrogenous bases


  The coding part of DNA and RNA
• Nitrogenous bases in DNA


  • A=T and C=G (complementary)
• Nitrogenous bases attach to each other by hydrogen bonds, allowing DNA to unzip for replication or to allow one side to be used as a template for making mRNA
• DNA triplets


  Contain information for making a protein by specifying the order of amino acids used to make the protein
• DNA never leaves the nucleus, its information is transferred to mRNA which does leave the nucleus and contains codons which directly determine the order of amino acids in a protein that it codes for
• The protein determines the trait that an organism possesses
• DNA can replicate but proteins cannot, hence the need for DNA
• RNA


  A single strand, not double stranded, and contains uracil (U) instead of thymine (T)
• Role of DNA


  • As a blueprint for protein formation, and its location in the cell
• Genes


  Sections of DNA that can code for protein production
• DNA replication


  Where it happens, and what each new DNA molecule is composed of (half old half new)
• DNA replication occurs before a cell divides, either by mitosis (if body cell) or meiosis (if a sex cell in gonad destined to become a gamete)
• Protein synthesis


  1. mRNA uses DNA as a template, and is made in the nucleus but moves to the cytoplasm where with the help of ribosomes that read the mRNA to help make a protein

  2. Role of tRNA in bringing amino acids to the growing amino acid (polypeptide/protein) chain
• Each tRNA has an anticodon of three bases on one side carries a specific amino acid on the other side
• The anticodon of tRNA allows it to bind temporarily to mRNA when the ribosome (in a complementary manner) is over that part of the RNA
• Later the tRNA will be released after its amino acid is added to the one that came before it in the growing polypeptide chain
• Later on when done, the polypeptide chain folds up to make a final protein (based on the sequence of amino acids) which allows it to perform a specific function (which is based on its shape)
• Transcription of DNA into mRNA


  How to determine which amino acids the mRNA codons (3 letters each) code for (translation), given a codon chart with the amino acids
• Enzymes are used to make mRNA (or any other kind of RNA) from a DNA template such as RNA polymerase
• Mutations


  Changes in DNA, including substitution (one base for another), deletion (loss of one base or base pair), and insertion/addition (adding an extra base or base pair)
• Frameshift mutations (insertion/addition and deletion) cause problems not only with the triplet they affect and the corresponding codon in mRNA but also with other codons downstream of the affected codon in the mRNA
• Mutations must be present in the sperm or eggs to get to the next generation, and these cells are located in gonads
• Cloning of plants and mammals


  1. How it is done and who the baby is a clone of

  2. Why the donor egg must have its own nucleus removed before inserting the donor nucleus
• Plant tissue culture


  A way to clone plants from individual cells or parts of plants in a lab, and a form of vegetative propagation
• Cloning is a form of asexual reproduction, like the division of a protista into two, so it involves mitosis
• There are ethical issues/concerns involved with cloning humans which is why it hasn't happened yet
• Genetic engineering of bacteria and GMOs

  1. Why it is done - to make hormones such as insulin or growth hormone cheaply for people and also for other products that the bacteria have no use for but we do

  2. How a recombinant plasmid is made - a restriction enzyme is needed to cut the plasmid once and also to cut the human or other DNA from which a gene is being taken twice, and the same restriction enzyme must be used for both cuts to create complementary sticky ends
• Restriction enzymes


  Cut DNA, creating blunt or sticky ends
• DNA ligase joins the foreign DNA to the plasmid, connecting the sugars and phosphate backbones via covalent bonds after hydrogen bonding has occurred between complementary sticky ends
• CRISPR/Cas9 is another way to do genetic engineering, but you do not have to know exactly how it works
• Genetic engineering could potentially bring back recently extinct species like the wooly mammoth, but there are pros and cons to this idea
• GMO organisms always have altered DNA when compared to the normal wild type organism, and it is not a good idea to let GMO organisms mix with wild populations since they may pass that new trait into the wild populations which may not be desirable and/or outcompete the normal form of the species
• Restriction enzymes are used in both genetic engineering and electrophoresis, but electrophoresis can use restriction enzymes that make blunt cuts unlike with making recombinant DNA via recombinant plasmids
• Electrophoresis


  1. Understand diagrams, that we need to use the same restriction enzyme on all samples that are loaded into the wells

  2. DNA fragments move away from the wells towards the positive end when electricity is turned on

  3. Allows us to compare DNA from different sources - if all bands match, the DNA comes from the same source (or identical twins), if there is a lot of similarity between different organisms or individuals DNA bands but not a perfect match, it means they are closely related

  4. Smaller bands move faster than large bands towards the positive end, because DNA has a negative charge and the bands separate due to size differences

  5. The bands require some kind of stain to be seen
• PCR (Polymerase Chain Reaction)

  1. Used to amplify (multiply) a selected section of DNA (the target sequence) into large quantities

  2. Requires heating and cooling cycles, so the DNA polymerase enzyme used has to be heat resistant (Taq polymerase)

  3. Materials needed include enzymes, a DNA template, and nucleotides (subunits of DNA) with their attached base (A, T, C, or G)
• Genomic analysis requires breaking a cell's DNA into many fragments, figuring out their bases (letters) then using a supercomputer to figure out how they fit back together, which can give us much information about which alleles of which genes cause diseases, but there are also risks to knowing that information, for example jobs or insurance companies could discriminate against individuals who have less favorable genetic profiles
• Amino acids


  Building blocks of proteins that are linked together in a specific order to form a protein chain during protein synthesis
• Protein synthesis


  The process by which the genetic information in DNA is used to produce a protein
• Nucleic acids


  Molecules that carry genetic information in cells, including DNA and RNA