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It is hard to define life, but it is generally accepted that the cell is the basic unit of life. Usually, cells are tiny, very complicated and have DNA inside. Animals, plants, fungi have life-cycles involving a body, which means they are many cells that co-exist and are usually descended from a single cell - a fertilised egg. Protists and bacteria are single cells. All these different types of life have DNA. However, some things that are not made of cells also have DNA. For instance, viruses are very small packages of DNA and protein that replicate, but are considered non-living.
Usually researchers studying genetics and disease aren’t working on specific cures but instead trying to understand the molecular basis of disease with the hope that it may lead of improved treatments. Even when we understand how genetics is involved in a disease, curing the disease it is not as simple as replacing a gene or removing a mutation. This is because many visible traits like disease may require the interaction of many genes and specific environmental conditions before they appear. In its most general form, traditional genetics has been trying to understand how life works by pulling it apart to the smallest bits (genes and proteins), whereas Synthetic Biologists are trying to understand life by putting the pieces back together.
DNA is being replicated all the time, all through your body, and every time it is replicated there is a chance of mutation. Everyone has mutations and most are non-events. There is a whole group of mutations that are required together before cells become cancers. The vast majority of the mutations that accumulated in your parent's bodies were not inherited by you, as only DNA in sperm and egg cells is inherited. Counter-intuitively, if an organism had no mutations or genetic change at all, their lineage might be outcompeted and die eventually since they would lack the genetic diversity required to evolve over time.
The first human genomes were sequenced in America around 2001, for about $300,000,000, though the total research costs were higher. Technological advances have decreased the price and time required since then. At the moment it costs around $3000 and may take a few days, but every year it gets cheaper and faster. This does not include the cost of interpreting all the information after a genome has been sequenced, and without interpretation a sequenced genome is as meaningless as a novel in another language. Many, many genomes of other species, alive and extinct, are being sequenced.
We inherit 23 chromosomes from each of our parents, making 46 in total, though sometimes people inherit more or fewer chromosomes and this can affect their development. Each chromosome is a bundle of DNA with many, many genes on it, and the chromosomes differ in size and the genes they carry. All cells containing our parent's DNA have all 46 chromosomes, meaning they have two copies of each gene, one from our mother and one from our father. Sperm and egg cells are unique because they mix half of our mother's and half of father's DNA together, to make just 23 chromosomes, meaning they contain half the genetic material of all our other cells. Inheritance works differently for different species. Some might have more or less chromosomes, some might not organise DNA into chromosomes. The significant thing to remember is that DNA is inherited, that both DNA and environment are important for determining traits, and that without inheritance natural selection could not occur.
There are field trials of genetically modified (GM) organisms in every Australian state except Tasmania. In 2007, GM cotton made up 90% of the Australian cotton crop. The insulin used by diabetics is derived from bacteria or yeast engineered with human insulin genes. Most universities, and thus most major cities, will have labs devoted to this sort of work because it is almost impossible to study genetics without some form of genetic manipulation.