General Biology 2

• Traditional breeding, also known as classical or conventional breeding, involves mating two members of a specific species, each possessing different and desirable traits, to create a hybrid individual with both traits
• Classical breeding does not involve direct manipulation of genetic material and is used to produce organisms with desired traits by selecting and mating individuals
• Classical breeding has been instrumental in creating modern agriculture, domesticated plants and animals, all cat and dog breeds, and many industrial yeast strains
• Classical breeding relies on natural variation present in the gene pool of a population and the principles of heredity, where traits are passed to offspring as observable characteristics of an entire set of genes in the cells
• In the process of classical breeding:

  • Selection of Parental stock: Individuals with desirable traits are chosen as parents based on phenotypic traits
  • Crossbreeding or Hybridization: Selected parents are crossed to produce offspring with a combination of genetic material; crossbreed within the same species, hybrid offspring have parents from two separate species
  • Selection of Offspring: Resulting offspring are evaluated, desired traits are selected for further breeding
  • Repetition of the Process: The breeding cycle is repeated over several generations to refine and stabilize desired traits, improving varieties of crops, livestock, and other organisms
• Translation is the process by which mRNA is decoded to produce a protein, involving a ribosome reading the mRNA and assembling amino acids into a protein chain specified by codons

  
• Genetically engineered bacteria can produce human proteins like cytokines by splicing the cytokine gene into a plasmid, which is then returned to the bacterium for production

  
• Genetic engineering involves using recombinant DNA technology to alter the genetic makeup of an organism, often by adding a gene from another species to give it a desired phenotype
• Genetic engineering can involve altering DNA by changing base pairs, deleting regions of DNA, introducing additional copies of genes, or combining DNA from different organisms
• In genetic engineering, two different cell's DNA are combined and inserted into the host genome via a vector, with the gene of interest inserted using plasmid DNA vectors
• The process of genetic engineering can be divided into 5 steps: selecting and isolating the candidate gene, selecting and constructing a plasmid, gene transformation, inserting DNA into the host genome, and confirming the insert
• Steps in cloning a gene involve isolating the DNA of interest, cutting DNA with restriction endonucleases, combining target and vector DNA, and confirming the insert
• Restriction endonucleases cut DNA, creating "sticky ends" that can recombine with complementary DNA sequences, a crucial step in molecular cloning
• After DNA is cut by restriction endonucleases, the target and vector DNA are combined with DNA ligase to repair the covalent bonds on the sugar-phosphate backbone of the DNA
• Gene therapy process:

  • A normal healthy gene is inserted into a vector
  • The vector with the healthy gene is inserted into the target site
  • The mutant gene is replaced by the normal healthy gene
• Steps of genetic engineering:

  1. Extract a plasmid from a bacterium

  2. Use restriction enzymes to cut the plasmid open

  3. Insert the human insulin gene into the plasmid

  4. Insert the plasmid into a bacterium

  5. Grow the bacterium in a fermenter

  6. Extract the insulin protein from the bacteria

  7. Purify the insulin protein

  8. Insulin protein is ready for distribution
• Ways to introduce plasmids into host organisms:

  • Biolistics: using a "gene gun" to fire DNA-coated pellets on plant tissues
  • Plasmid insertion by Heat Shock Treatment
  • Electroporation: expanding membrane pores through an electric "shock"
• Methods to screen recombinant cells:

  • Selection of plasmid DNA containing cells
  • Selection of transformed cells with the desired gene
  • PCR detection of plasmid DNA
• Genetically modified organisms (GMOs):

  • Developed based on the central dogma of transcription and translation of genes
  • Flavr-Savr Tomato: modified ripening process
  • Bt-Corn: incorporates production of a toxin from Bacillus thuringensis in corn plants
• Uses of genetically engineered organisms:

  • Source of DNA for replication
  • Source of RNA like antisense RNA
• Genetic engineering applications:

  • Scientific research, agriculture, and technology
  • Improving resilience, nutritional value, and growth rate of crops like potatoes, tomatoes, and rice
  • Developing sheep that produce therapeutic proteins in their milk for treating cystic fibrosis
  • Creating worms that glow in the dark for studying diseases like Alzheimer’s
• Genetic engineering allows for the rapid production of genes associated with diseases like breast cancer in E. coli, without repeated tissue donations from human volunteers
• Antisense RNA is single-stranded RNA complementary to mRNA that controls target genes and can prevent diseases caused by specific proteins
• Using microbes to manufacture proteins due to their rapid replication rate, such as insulin or human growth hormone
• Steps in producing insulin using genetically modified bacteria:

  1. Extract a plasmid from a bacterium

  2. Cut the plasmid open with restriction enzymes

  3. Insert the human insulin gene into the plasmid

  4. Insert the plasmid into a bacterium

  5. Grow the bacterium in a fermenter

  6. Extract the insulin protein from the bacteria

  7. Purify the insulin protein

  8. Insulin protein is ready for distribution
• Translation is the process by which mRNA is decoded to produce a protein, involving a ribosome reading the mRNA and assembling amino acids into a protein chain specified by codons on the mRNA
• Eons of geological time are subdivided into eras, with the Phanerozoic eon divided into three eras: Paleozoic, Mesozoic, and Cenozoic
• The Paleozoic era is characterized by trilobites, the first four-limbed vertebrates, and the origin of land plants
• The Mesozoic era represents the "age of dinosaurs," with the first appearances of mammals and flowering plants
• The Cenozoic era, known as the "age of mammals," is the era during which we live today
• In the United States, the Carboniferous is divided into two separate periods: the Mississippian and the Pennsylvanian
• The Mesozoic era is divided into the Triassic, Jurassic, and Cretaceous periods
• The Neogene is divided into the Miocene and Pliocene epochs, while the Quaternary is divided into the Pleistocene and Holocene epochs
• Gene flow, also known as migration, is any movement of individuals and/or genetic material from one population to another, contributing to genetic variation
• Horizontal gene transfer (HGT) is a process where an organism acquires genetic material from another by asexual means, playing a major role in the evolution of organisms like bacteria
• Steps of producing insulin using genetically modified bacteria:

  • Step 1: Extract a plasmid from a bacterium
  • Step 2: Use restriction enzymes to cut the plasmid open
  • Step 3: Insert the human insulin gene into the plasmid
  • Step 4: Insert the plasmid into a bacterium
  • Step 5: Grow the bacterium in a fermenter
  • Step 6: Extract the insulin protein from the bacteria
  • Step 7: Purify the insulin protein
  • Step 8: Insulin protein is ready for distribution

  
• Genetically engineered bacteria can be used to produce human proteins like cytokines by:

  • Taking a DNA strand from a cytokine-producing cell and cutting out the cytokine gene
  • Splicing this gene into a plasmid, a small piece of DNA that can replicate independently of the bacterial chromosome
  • Returning the plasmid to the bacterium, which can now produce the human cytokine

  
• Gene flow in plant populations:

  • Plant populations can experience gene flow by spreading their pollen long distances to other populations through wind, birds, or insects
  • Pollen contains male gametes and can fertilize plants in different populations, minimizing genetic differences
• Genetic drift:

  • Random fluctuations in gene frequency, more significant in small populations
  • A stochastic process influencing allele frequency due to sampling error from generation to generation
  • Can lead to the loss of beneficial traits within a generation
  • Alleles are responsible for variations in a trait
• Natural selection:

  • Leads to evolutionary change by favoring individuals with certain traits for survival and reproduction
  • Operates through differential reproductive success of individuals
  • Causes populations to become adapted to their environments over time