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Discussing how genetics is used today in medicine, agriculture, and forensic science.
What if you could 'copy and paste' a single trait—like the ability to glow in the dark or resist a specific virus—from one living thing into another?
Long before we knew about DNA, humans were already 'editing' life. Selective breeding (or artificial selection) is the process of choosing parents with particular characteristics to breed together and produce offspring with more desirable traits. For example, every dog breed from a tiny Chihuahua to a massive Great Dane is a result of humans selecting for specific genes over thousands of years. In agriculture, farmers use this to create crops that produce more food. If a farmer has 100 tomato plants and only are resistant to drought, they will breed those specific plants to ensure the next generation survives better.
1. Thousands of years ago, wild corn (Teosinte) was a tiny grass with only a few hard kernels. 2. Ancient farmers selected the plants with the largest, softest kernels to replant. 3. Over generations, the frequency of 'large kernel' genes increased. 4. Today, we have modern corn, which is significantly larger and more nutritious than its ancestor.
Quick Check
In selective breeding, what determines which traits are passed on to the next generation?
Answer
Human choice (selecting parents with desirable traits).
While selective breeding works with existing traits, Genetic Engineering allows scientists to change the DNA of an organism directly. This is a key part of Biotechnology. Scientists use molecular 'scissors' to cut a gene from one organism and 'paste' it into another. This creates a Genetically Modified Organism (GMO). In medicine, this technology is used for Gene Therapy, which aims to treat or prevent diseases by inserting a healthy gene into a patient's cells to replace a mutated or 'broken' one.
1. Scientists identify the human gene responsible for producing insulin. 2. They use enzymes to cut this gene out of human DNA. 3. They insert this gene into the circular DNA (plasmid) of a bacteria cell. 4. The bacteria 'reads' the human code and begins producing human insulin. 5. This insulin is collected and used to treat people with diabetes.
Quick Check
What is the primary difference between selective breeding and genetic engineering?
Answer
Selective breeding relies on natural mating of chosen parents, while genetic engineering involves direct laboratory manipulation of DNA.
Genetics isn't just for labs; it's in our courtrooms and hospitals. DNA Profiling uses the of DNA that is unique to every individual to identify people in forensic science. However, this power brings up Bioethics—the study of ethical issues in biology. If we can screen an embryo for diseases, should we also be allowed to choose its eye color or intelligence? If an insurance company sees your genetic profile and finds a probability () of a future heart condition, should they be allowed to deny you coverage? These are the questions society must answer.
Consider a scenario where a person uploads their DNA to a genealogy website to find relatives. 1. Police use that database to find a partial match to a cold-case crime scene. 2. They identify the user's second cousin as a suspect. 3. Challenge: Is it ethical to use a person's private genetic data to investigate their family members without their direct consent?
Which process involves choosing two dogs with soft fur to mate in hopes of getting soft-furred puppies?
What do scientists use to create a Genetically Modified Organism (GMO)?
Gene therapy is a technique used to identify criminals using their unique DNA fingerprints.
Review Tomorrow
In 24 hours, try to explain the difference between a GMO and a selectively bred plant to a friend or family member.
Practice Activity
Research one 'GMO' crop found in your local grocery store and find out what specific trait was added to it (e.g., pest resistance or vitamin enrichment).