Genetic Engineering

• Genetic Engineering is Module 1 of General Biology 2 and taught by Sherwin M. Bernabe.
• The MELCs cover processes in genetic engineering and applications of recombinant DNA.

Lesson 1: Genetic Engineering

• Every type of tissue contains a complete copy of your body's DNA.
• Pigs have received jellyfish bioluminescent genes as embryos and glow as a result.
• Genetic editing in pigs to reduce immune rejection has made organ transplants from pigs to humans possible.
• Gene Editing is the production of transgenic animals that contain genes from another species
• Pigs are promising organ donors of the heart, heart valves, corneas, skin, kidneys, and protected tissues.
• A genetically modified pig heart was transplanted into a 57-year-old man with life-threatening heart disease.
• Genetically modified live-cell pig skin was used to temporarily close a burn wound in 2019.

Engineering Traits

• DNA contains all of the genetic information to determine an organism's traits or characteristics.
• Modifying the DNA enables engineers to determine which traits an organism will possess.
• Engineers created the first goat able to produce spider silk proteins in 2000 with a variety of benefits.

The Chemical Structure of DNA

• DNA polymer is made of nucleotide units
• Nucleotides are made of a sugar group, a phosphate group, and a base.
• There are four different bases: adenine, thymine, guanine, and cytosine
• DNA strands are held together by hydrogen bonds between bases: Adenine (A) pairs with thymine (T), guanine (G) pairs with cytosine (C), and adenine pairs with uracil (U) in RNA.
• The bases on a single strand of DNA act as a code. The letters form three letter codons that code for amino acids.
• RNA polymerase transcribes DNA into mRNA (messenger ribonucleic acid)

DNA as a Twisted Ladder

• The ladder's outside is composed of alternating sugar and phosphate molecules.
• The sugar is called deoxyribose.
• The ladder's rungs are composed of base pairs
• Adenine only pairs with thymine, and cytosine only pairs with guanine to form a rung.

DNA

• DNA, or deoxyribonucleic acid, is hereditary material in nearly all living organisms
• DNA carries the instructions for growth, development, functioning, and reproduction.
• It is a molecule composed of two coil around each other to form a double helix.
• Each strand is made of a sequence of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G)
• Bases pair specifically: A with T and C with G
• Gene is a DNA segment that encodes genetic information for the unique characteristics and traits of an organism
• DNA determines inherited features and plays a critical role in processes such as protein synthesis and cellular replication.

Why Proteins are Important

• Proteins perform the functions of serving as catalysts for reactions, performing cell signaling, transporting molecules across membranes, and creating structures within organisms
• When a protein is created by its gene, the gene is said to be "expressed."
• Genes that code for pigment have visual expression and create phenotypic traits
• Phenotypic traits are the expression of a gene in an observable manner, like hair color

How DNA is Used

• Genetic engineering is the direct altering of an organism's genome through manipulation of the DNA.
• DNA is a universal language, made up of the same nucleotide building blocks, such that genes from one organism can be read by another organism

Genetic Engineering Technique

• Identify an organism with a desirable gene
• Extract entire DNA from the organism.
• Remove this gene from the rest of the DNA using a restriction enzyme that "cuts" the DNA by breaking bonds at the location.
• Insert the new gene to an existing organism's DNA via various processes
• Inserting the isolated gene to a circular piece of DNA bacteria uses, called a plasmid, is a common method when modifying bacteria.

Lesson 2: Recombinant DNA Technology

• GloFish are genetically modified zebrafish available to the public that glow in fluorescent colors due to the insertion of green fluorescent protein (gfp) genes created using recombinant DNA technology.
• GloFish have been approved by the U.S. FDA, but they sparked discussions on genetically modified animals.
• This field of genetic engineering originated in the 1960s and 1970s when scientists began exploring DNA recombination processes.
• Modern technology allows isolating and replicating specific genes via DNA cloning.
• DNA tech is a scientific method used to manipulate and alter the genetic material of organisms.
• This technique combines DNA molecules from different sources into a single molecule to create new genetic combinations.
• The process typically includes isolating a gene of interest, inserting it into a vector, and then introducing it into a host organism that can replicate and express the gene
• It includes production of insulin, growth hormones, and vaccines, as well as advancements in agriculture through genetically modified crops with improved resistance to pests and environmental conditions.
• Recombinant DNA technology is a cornerstone of modern biotechnology

Genetically Modified Plants

• Recombinant DNA technology has significantly improved crop varieties by creating genetically modified organisms (GMOs).
• The Ti plasmid from Agrobacterium tumefaciens, a soil bacterium, is often used to insert desired genes into plant cells
• Recombinant DNA increases pest resistance and enhances nutritional value.
• Bt corn expresses a gene from Bacillus thuringiensis to resist corn borer disease.
• Golden rice is engineered to produce beta-carotene.
• Rice and potatoes are modified as natural vaccines.
• Herbicide-resistant soybeans enable weed control without damaging crops.

Applications of Genetic Engineering

• Gene Therapy: Correcting genetic disorders by introducing functional genes into patients' cells.
• Vaccine Development: GMOs are used to produce safer and effective vaccines, such as those for hepatitis B and COVID-19.
• Antibiotics and Hormones: Production of antibiotics, human growth hormones, and therapeutic proteins through genetic engineering.
• Crop Improvement: Enhancing resistance to pests, diseases, and environmental conditions.
• Nutritional Enhancement: Developing fortified foods like golden rice, rich in beta-carotene.
• Bioherbicides and Biopesticides: Creating GM crops like Bt corn to naturally resist pests.
• Bioremediation: Engineering microorganisms to clean up oil spills, degrade plastics, or detoxify pollutants in soil and water.
• Carbon Sequestration: Modifying plants and microorganisms to absorb and store atmospheric carbon dioxide.
• Biofuel Production: Engineering microbes to produce bioethanol, biodiesel, and other renewable energy sources.
• Biodegradable Plastics: Creating microorganisms capable of synthesizing environmentally friendly plastics.
• Enzyme Production: Generating industrial enzymes for detergents, textiles, and food processing.
• DNA Profiling: Forensic genetic engineering tools identify individuals and solve crimes.
• Custom Organisms: Designing organisms with specific functions, such as bacteria to produce synthetic drugs or bio-sensors for detecting toxins.
• Transgenic Models: Modifying animals like mice for studying human diseases and testing new treatments.
• Xenotransplantation: Engineering animals to grow human-compatible organs.
• Stress-Resistant Organisms: Engineering microbes and crops to survive extreme conditions for space colonization.

Ethical and Safety Considerations

• Potential negative effects exist for genetic modifications: allergic reactions, gene transfer between plants and pathogens, and harm to ecosystems.
• GM crops like Bt corn and Bt eggplant (Bt talong) have been adopted in the Philippines though Bt eggplant was at one point banned due to safety concerns.
• Experts say approved GM crops are safe, and reduce the need for pesticides.

CRISPR-Cas9 Technology

• Recombinant DNA technology using restriction enzymes only inserted entire DNA segments into plasmids

CRISPR-Cas9 Origin

• CRISPR-Cas9 is a natural defense mechanism in bacteria and archaea against viruses and plasmids.
• CRISPR is an acronym: Clustered Regularly Interspaced Short Palindromic Repeats
• The Cas9 Protein acts as "molecular scissors to cut DNA at specific locations guided by sing RNA (sgRNA).
• The sgRNA can be engineered to target almost any DNA sequence in the genome.
• CRISPR-Cas9 enables targeted modifications (gene insertion, deletion, or repair).
• It has applications in gene therapy, agriculture, drug development, and creating genetically modified organisms (GMOs).
• Compared to earlier techniques, CRISPR-Cas9 is faster, cheaper, and more efficient.
• Ethical concerns are raised however about editing human embryos and creating "designer babies".
• Jennifer Doudna and Emmanuelle Charpentier were awarded the Nobel Prize in Chemistry for their work on CRISPR-Cas9 in 2020.
• Limitations of off-target effects, incomplete edits, and delivery into cells exist
• Beyond cutting DNA, CRISPR can also activate or repress gene expression without cutting. CRISPR has a global impact and is wWidely adopted in research and industries due to impact.

Examples of Genetically Modified Organisms

• Golden Rice produces beta-carotene for combatting vitamin A deficiency in developing countries.
• Bt Cotton expresses the Bacillus thuringiensis toxin to resists cotton bollworm, which reduces chemical pesticides.
• Roundup Ready Soybeans are resistant to glyphosate enabling farmers to spray herbicide without harming the soybeans. GloFish express fluorescent proteins from jellyfish or coral that glow under ultraviolet light.
• AquAdvantage Salmon grows faster due to a gene from Chinook salmon promoting growth throughout the year.
• Innate Potato reduces bruising and black spots, and produces less acrylamide.
• Herbicide-Tolerant Canola resists herbicides like glyphosate.
• ZapMail™ Tomato resists to certain viruses to help farmers protect their crops and reduce losses.
• Rainbow Papaya resists to the ringspot virus.
• Virus-Resistant Squash resists viral infections with zucchini yellow mosaic virus and squash leaf curl virus.

Test your knowledge of genetic engineering with this quiz. Explore topics such as DNA modification, transgenic animals, spider silk protein production in goats, and DNA base pairing. Consider ethical implications and potential limitations of genetic engineering.