GENETICS
SCIENCE & SOCIETY
Genetics 101
What is DNA?
DNA stands for deoxyribonucleic acid and is material found in all humans and most organisms
Most DNA is located in the cell nucleus but a small amount can also be found in the mitochondria
Each one of the 30 trillion cells in the human body contains 2 metres of DNA
The DNA is made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T)
The chemical bases pair up, A and T go together and C and G go together
Each pair also attaches to a sugar and phosphate molecule, altogether forming whats called a nucleotide
Structure of DNA
The nucleotide forms two long lines that spiral around each other, called a double helix. The double helix takes the shape of a ladder with the sugar and phosphate molecules forming the outside lines and the base pairs forming the middle lines. Hover over the image below to see a labelled version of DNA
Guanine
Cytosine
Adenine
Thymine
Sugar and Phosphate molecules
1½ cups
Butter
3 cups
Flour
What Are Genes?
Genes are a unit of heredity found on chromosomes and made up of DNA
There are two copies of every gene, one comes from the father and one from the mother
Genes can vary largely in size, they can be as small as a few hundred DNA bases or as large as millions of DNA bases
Almost all of our genes are identical to other people, however, there are a few called alleles which are unique
If an allele is recessive, such as having blue eyes, the person will need two copies in order to get blue eyes
If an allele is dominant, such as having brown eyes, the person only needs one allele to get brown eyes
Human Genome Project
The Human Genome Project was a publicly funded international research effort that began in 1990 and lasted until 2003. Its aim was to find the sequence of the nucleotide and what genes it contained. As a result of the project, over 1,800 disease genes have been discovered and there are now more than 2000 genetic tests that can be done.
Genetic Engineering
Genetic engineering involves manipulating genes using biotechnology. Scientists will identify a gene responsible for a certain function in one organism and insert it into another organism. This means that the second organism will have all of its original genetic makeup plus additional characteristics that come from the first organism. Using this technique, genes can be swapped within their own species, different species or sometimes to create an entirely new one altogether. Click through the slideshow below to learn about the different types of genetic engineering that can be done.
Genetically Modified Crops
Genetically modified crops have become increasingly popular in the last few decades, with over 18 million GMO seeds now being planted worldwide. Engineering these plants allows breeders to select desirable traits in one plant, such as resistance to disease, and transfer it to another plant that needs improvement. In 2014, as a result of using GMO's, farmers produced the same amount of crops they usually did but used 48 million fewer acres of land.
CRISPR CAS 9
Genetic editing is an incredibly complicated scientific process which is why the simplicity and versatility of CRISPR/CAS 9 is drawing wide attention in the scientific community. CRISPR/CAS 9 is a piece of technology that allows scientists to either insert, remove or change sections of a DNA sequence. It's made up of two parts; an enzyme called Cas9 that has the ability to cut DNA like scissors, and RNA which is a predesigned sequence that guides Cas9 to ensure it makes the cut in exactly the right place.
This means that in theory, CRISPR/CAS9 could be used to target specific genes that cause diseases such as cystic fibrosis or even high cholesterol. It's likely to be a long time before it's put into widespread use for humans as much more research is still required. It also faces significant objections from people who believe it's ethically wrong. One common objection is based on the fact that changes to the genetic makeup will be hereditary therefore it's impossible to know the long-term effect on our future generations.
Genetic Engineering vs Cloning
Many people talk about genetic engineering and cloning as if they're the same thing, but in fact the process is opposite from one another
Unlike genetic engineering that's altering genes to create a different organism, cloning is producing an exact copy with identical genes and DNA
Although human cloning is still only theoretical, many plants and animals have successfully been cloned, most notably Dolly the sheep in 1996.
Run by scientists at the Roslin Institute in Edinburgh, Dolly was the first mammal to ever be cloned using a somatic cell nuclear transfer technique.
The technique involves taking the nucleus from an adult cell and inserting it into an egg cell without a nucleus. By giving it an electiric shock, it will start dividing and can be put in the mother.
Dolly died when she was 6 due to lung disease. Despite much speculation from the press, scientists confirmed that her death was unrelated to the fact that she was cloned.
