It is a process where humans use plant or animal breeding to selectively develop physical traits/characteristics by choosing which male or female species will sexually reproduce and have a offspring together.1
It is a practice of mating individuals with desired traits as means of increasing the frequency of those traits in a population2
It involves selecting individuals of a species that has the characteristics of interest in the hope that their offspring inherit those desirable characteristics3
It is the process of increasing frequency of desirable traits in future generations by only allowing individuals with those traits to reproduce.4
Why Selective Breeding?
Humans have done selective breeding to frequently produce organisms with desirable traits that may be more economically beneficial or aesthetically beneficial to humans.
Selective breeding has helped humans increase crop yields by selectively picking crops that can produce larger yields or provide more resistant crops.4
Similarly, selective breeding can be also used in poultry and aquaculture farmers for increased opportunities for large market gains. It can also be used to increase survival rates of livestock, lessen costs for feed use, and in general, be more heavier for animals bred for food. 54
Humans have also been selectively breeding dogs, cats or horses for companionship or entertainment. This is due to the fact that some people tend to seek traits that fit a certain criteria for companion animals.4
Selective Breeding Methods
Inbreeding
It is breeding between two species which are closely related to one another, without any regard to how close they are.
It is the process of breeding a parent organism to its direct offspring in order to increase the chances of getting a desired trait.
One major downside of this method is inbreeding depression.
It occurs when animals that are closely related are bred together too much that deleterious/harmful traits start to show up.
This is because as the genes become more and more uniform, the more likely will harmful recessive traits start to pair up.
Linebreeding
A specific type of inbreeding that, unlike inbreeding, it tries to breed animals over some distance in the family line.
For example, the descendants of an animal with a common ancestor, or between different cousins.
This reduces the risk of inbreeding depression for the first few generations.
One downside of linebreeding is that it lessens the genetic diversity in the long term.
This is because the gene pool is much smaller that the offspring has an increased risk for genetic disorders and inbreeding depression in the long term.
Outcrossing
Two individuals that are not closely related who both share a specific trait are crossed to produce an offspring.
It works because if an ancestor carries a specific trait and carries all the way to its present descendants, then all individuals within this population has that trait.
This principle is called the founder effect.
One major downside is that it is more unpredictable than inbreeding methods.
Some ways that this may occur are:
The desirable traits from the first generation (also known as hybrid vigor) may slowly diminish and wear of every generation that passes.
This is also known as outcrossing depression.
While outcrossing can significantly avoid inbreeding depression, it may result in a higher overall inbreeding rate if not managed carefully.
Due to more genetic diversity, some traits necessary for an individual’s survival may become ineffective as foreign traits are introduced.
This is called genetic swamping.
In some ways, organisms that may be suited for outcrossing may be separated geographically, or pollinators may be scarce in the case of plants for outcrossing to begin.
Cloning
Cloning describes the processes used to create an exact genetic replica of another cell, tissue or organism.
The copied material, which has the same genetic makeup as the original, is referred to as a clone.
The most famous clone was a Scottish sheep named Dolly.
The artificial cloning of organisms, sometimes known as reproductive cloning, is often accomplished via somatic-cell nuclear transfer (SCNT), a cloning method in which a viable embryo is created from a somatic cell and an egg cell.
In 1996, Dolly the sheep achieved notoriety for being the first mammal cloned from a somatic cell. Another example of artificial cloning is molecular cloning, a technique in molecular biology in which a single living cell is used to clone a large population of cells that contain identical DNA molecules.
A scientific technique that is used for making exact genetic copies or clones of different living things. Cloning can be natural or artificial.
Examples
Some of the examples of cloning include budding and fragmentation which are natural methods of cloning observed in prokaryotic organisms. Examples of artificial cloning include Dolly the sheep and Elizabeth Ann, the ferret.
Dolly was a female Finn-Dorset sheep and the first mammal that was cloned from an adult somatic cell. She was cloned by associates of the Roslin Institute in Scotland, using the process of nuclear transfer from a cell taken from a mammary gland.
Elizabeth Ann is a black-footed ferret, the first U.S. endangered species to be cloned. The first cloned black-footed ferret. The animal was cloned using the frozen cells from Willa, a black-footed female ferret who died in the 1980s and had no living descendants.
Genetic Engineering
Genetic Engineering
It is the process of altering or modifying the gene expression of an organism through any artificial means.
It can be achieved by altering a single DNA base, deleting a gene, or replacing a region of DNA.
Organisms modified with genetic engineering are called GMOs or genetically modified organisms.
Process
The process for genetic engineering may be multifaceted, but it can summarized as follows:
Identify the gene that they wish to insert.
Geneticists may want to assess first what they want to accomplish with the organism.
They may then do genetic screens and a wide variety of tests to test which genes are the best candidates.
Isolate the gene.
Once the gene is identified, the a cell containing the gene can be retrieved and isolated.
In some cases, if a gene is well studied, it can be accessed in a genetic library.
If the gene sequence is known, but no copies of the gene is made, it can be artificially synthesized.
The cell is then opened, revealing the DNA inside.
From the DNA, the gene may then be separated by breaking the DNA into segments.
The DNA segments of interest are then extracted using gel electrophoresis.
Clone the gene.
The gene is then ligated or joined and placed inside the bacteria.
When the bacteria divides, the gene inside the bacteria also replicates, producing unlimited copies.
After the gene is cloned, the gene may be modified at this stage for it to become more effective.
Insert the DNA into the host genome.
Once the DNA is cloned, the DNA can now be inserted into the genome.
It can be done by:
using bacteria to naturally transport the DNA into the genome.
using microinjections, where it can be injected directly to the cell’s nucleus in animal cells.
using viral vectors, modified viruses designed to deliver genetic material to the animal cell.
shooting young plant cells with gold or tungsten covered with DNA
use electric shock to make the cell more permeable to the DNA
The organism is then regenerated to ensure all cells are transformed with the new gene.
Further tests are to be done accordingly to ensure that the gene is functional and active.
Applications
Genetic engineering has many applications in a variety of fields.
Medicine
It was initially used to mass produce human insulin using bacteria.
Now, it was now adapted for other uses, such as hormones, antibodies, vaccines, and other types of drugs
It was also used to create models that can be used to study other diseases affecting the human body, such as cancer, obesity, anxiety, aging and more.
It can also be used in humans to treat genetic disorders through genetic therapy.
This can be done by replacing defective genes with more effective ones
Research
Genetic engineering is often used to discover and identify the functions of certain genes.
Industrial
Some genetically modified bacteria can be used to make industry specific materials, such as cheese-making chemicals or even biofuels.
Outside of biological use, they are often seen used in cleaning up oil or toxic waste spills, detecting arsenic in water, or being used in biomining or bioremediation.
Agriculture
One of the most common applications of genetic engineering is in the creation of genetically modified crops or livestock to create genetically modified food.
It is often used to make crops resistant to pests and herbicide, make crops yield and produce more, or making the crop grow with more nutritional value than normal.
In livestock, they can be modified to grow faster than usual. Some animals are also engineered to produce vaccines, drug components, or even drugs themselves.