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Unlock This CourseFor thousands of years, humans have been improving plants and animals to make them more useful. Today, we have both traditional methods like selective breeding and cutting-edge biotechnology techniques that can directly change an organism's DNA. These genetic improvement techniques help us produce better crops, healthier livestock and even medicines.
Key Definitions:
Traditional selective breeding works with existing genes in a species, whilst modern genetic engineering can introduce genes from completely different species. Both methods aim to improve organisms, but genetic engineering is much faster and more precise.
Selective breeding is the oldest form of genetic improvement. Farmers and breeders choose the best individuals from each generation to produce offspring, gradually improving the population over time.
The process involves four main steps: selecting parents with desired traits, breeding them together, selecting the best offspring and repeating this process over many generations. Each generation should show gradual improvement in the desired characteristics.
Dairy cows bred for higher milk production, beef cattle for more meat and chickens for more eggs or faster growth rates.
Wheat with larger grains, tomatoes with better flavour and roses with different colours or longer stems.
Dogs bred for specific sizes, temperaments, or abilities like guide dogs or racing greyhounds.
Today's wheat produces much more grain per plant than wild wheat. Through thousands of years of selective breeding, farmers have created varieties that don't lose their seeds easily, have larger grains and grow shorter stems so more energy goes into grain production rather than stem growth.
Modern biotechnology allows scientists to make precise changes to DNA much faster than traditional breeding. These techniques include genetic engineering, cloning and tissue culture.
Genetic engineering involves directly manipulating an organism's DNA. Scientists can cut out specific genes from one organism and insert them into another, even between completely different species. This creates genetically modified organisms (GMOs).
Scientists use special enzymes to cut DNA at specific points. They then insert new genes and use other enzymes to join the DNA back together. The modified cells are grown into complete organisms with the new characteristics.
Genetic engineering has produced many useful organisms that would be impossible to create through traditional breeding alone.
Rice modified to produce vitamin A, helping prevent blindness in developing countries where rice is a staple food.
Bacteria modified to produce human insulin for diabetics, which is safer and more effective than insulin from animals.
Crops like Bt corn that produce their own pesticides, reducing the need for chemical spraying.
Cloning creates genetically identical copies of organisms. There are different types of cloning, from simple tissue culture to complex animal cloning.
Plant cloning is relatively simple and widely used in agriculture and horticulture. Many plants can be cloned from small pieces of tissue or even single cells.
Small pieces of plant tissue are grown in sterile conditions with nutrients and hormones. This can produce thousands of identical plants from a single parent plant very quickly.
Animal cloning is more complex and involves techniques like nuclear transfer, where the nucleus from an adult cell is placed into an egg cell that has had its nucleus removed.
Dolly was the first mammal cloned from an adult cell in 1996. Scientists took a nucleus from an adult sheep's mammary gland cell and placed it into an egg cell. This proved that adult cells could be reprogrammed to develop into a complete organism, revolutionising our understanding of development and opening new possibilities for medicine and agriculture.
Genetic improvement techniques offer many benefits but also raise important concerns that need careful consideration.
These techniques can solve many problems facing humanity, from food security to medical treatments.
Higher-yielding crops, resistance to diseases and pests and crops that can grow in harsh conditions help feed the growing world population.
Production of medicines like insulin, growth hormones and potential treatments for genetic diseases.
Reduced pesticide use, crops that need less water and plants that can clean up pollution.
Despite the benefits, genetic improvement techniques also raise important ethical, environmental and safety concerns.
Unknown long-term effects, potential for genes to spread to wild relatives, reduced genetic diversity and ethical concerns about modifying living organisms.
Most countries have strict regulations governing genetic modification to ensure safety whilst allowing beneficial research to continue. Scientists must conduct extensive testing before any genetically modified organism can be released.
New techniques like CRISPR gene editing are making genetic modification more precise and affordable. This could lead to treatments for genetic diseases, crops adapted to climate change and even the possibility of bringing back extinct species. However, these powerful tools require careful regulation and public discussion about their appropriate use.
As these technologies develop, it's important for everyone to understand both their potential benefits and risks. This knowledge helps us make informed decisions about which applications we support and how we want to regulate these powerful tools.