What Do Genes Do
Unravelling the Mystery of Genes
Hidden deep inside the organisms of life and beyond the reach of human understanding, until recent times, are the very basic building blocks that transfers information from generation to generation. They are genes, the tiniest particles of existence that are responsible for who we are and what we look like. But they are more than that. They carry messages that can determine how long we live, what diseases we will suffer, what sex we will be, how we will function as an individual, and so on.
As a medical student first off many years ago and then researching in my medical anthropology course at the Australian National University there was something about genes that grabbed my attention more than any of my other studies. They are markers that can determine the origin of a race, the migratory patterns of humans, and the secrets we might like to keep from the rest of the world. Genes determine us, who we are, how we speak, the shape of our nose, the color of our eyes and even our fertility and reproducing abilities.
Most people know of the double helix (pictured) and of the little knobs on either end of the cross bars but it is time to probe deeper and look inside to find out just how genes work. If you look closer at the cross bars you will see that they comprise smaller particles that are similar to particles on a skewer. They are not on a spike, however, but are held to together by electric charges that is another mystery of life.
This lens was a Summer Sunshine Awards winner and has contributed to March of Dimes Charity which also won $99 as a result.
The First Hint of the Structure of Chromosomes
As researchers worked to unravel how disease and characteristics were passed on a young lady, Rosalind Franklin, unraveled the crystallographic evidence of the structure of DNA when she attended Cambridge school of medical research. She worked in the same lab as Maurice Wilkins and Max Perutz. Her findings were recorded in a document that these two gentlemen then showed to two other scientists, Crick and Watson, without her consent or knowledge.
To backtrack a little "In 1944, Oswald Avery had shown that DNA was the "transforming principle," the carrier of hereditary information, in pneumococcal bacteria" (cited Profiles in Science - National Library of Medicine). In 1951 Franklin began her research through X-rays of the structure of cells and gradually unearthed the double helix. The constant exposure to X-rays probably induced the ovarian cancer from which she died in 1958 without recognition for her part in the discovery that would change medicine forever.
The image is from Wikipedia open source and although it is dark it is nowhere near the faint outlines of genes that Franklin first saw under X-ray and she still had to explain what it meant. This took months of her time as she was not a biomolicular scientist as the others in her vicinity were. So there is a chance she may never have gotten any further, but things were taken out of her hands by the young enthusiastic, Crick and Watson, who were also working to unravel the genetic code.
Identifying the helix was the greatest triumph of her short life but once Crick and Watson got wind of it they quickly claimed it as their discovery and would later be awarded the Nobel Prize for physiological medicine. They published their findings in Nature in April, 1953
Women in Science
It was conventional thinking that women in science were not appreciated. This was a man's world and to take research conducted by a woman and simply adopt it as your own was the done thing.
Do You Think Women Were Badly Done By? - Very few were recognised for their contribution to science.
Should credit be given to Franklin for her part in discovering the double helix.
Amino Acids and Protein
Their role in genetic science
Amino acid comprises nitrogen. hydrogen. oxygen and carbon linked together by electronic valency. That is the charged particles of their atoms are held together by magnetic force. A whole string of these molecules form what is termed protein. That is usually an elastic type substance in living cells. In fact, it can be termed the basis of life.
This is what cannot be manufactured in the laboratory by artificial means unless living cells are used to start with.
My first introduction to amino acid came through Ribonucleic acid or RNA. This is found in living cells. Another form of an amino acid is Deoxyribonucleic acid or DNA. This is the substance that contains the genetic instructions of all living things. It is the storage place of information that determines characteristics in new cells. One might call it a code, a blueprint or even a recipe for construction of protein and RNA. The segments that carry this information are genes. Along with them the rest of the DNA fulfills either a structural purpose or it serves to regulate the use of the genetic material
The DNA is organised into long strains called chromosomes. It is these that form the double helix that Franklin identified. But it was 20 years later before the true function of these cell particles was properly understood and the science of genetics was born.
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Amino Acid Protein
Have You Considered How Life is Created? - Or is it something you would rather not delve into?
Do you want to know how life is created?
The Formation of New Life
How do genes work?
In the case of sexual reproduction the two sex cells (gametes) come together. In each are a single set of chromosomes known as either an X chromosome in the case of the egg or an X or Y chromosome in the case of the sperm. Along each chain lies a set of near matching genes that will determine everything about the new life form, including its sex. During fertilisation they pair up in a remarkable display that can be observed through a microscope.
It doesn't matter the species of animal or plants. The results are the same. Some plants are reproduced sexually through male and female sex organs. These include ferns, vegetables, and fruits, e.g. kiwi fruit
The person responsible for discovering that genes follow specific laws was Gregor Mendel, an Augustinian priest. During the mid nineteenth century he experimented with peas and determined that they passed on inherited traits that fitted a specific pattern. From this he worked out that genes can be dominant or recessive and that one in four offspring carry double recessive genes while two in four have a recessive and dominant gene and one in four has only dominant genes. Recessive genes are those which carry unusual traits This is the simplest way to explain it although it is more complex than that.
When the two chromosomes in a mating come together it depends on the type of gene, that is whether it is recessive or dominant, that determines the characteristics of the offspring. For example if one pairs a recessive gene for dark skin color with a dominant gene for white skin the offspring will have white skin but it will carry a recessive gene for dark skin into the next generation. If then mated with another recessive gene for dark skin in the next or future generation then the offspring will have dark skin. this applies for any condition.
Mendel first demonstrated this in peas and established the law of inheritance, called Mendel's law.
It means that without the two chromosomes in the sex cells coming together there would be no offspring as an individual of any sexually reproduced species cannot survive without the double set of genes. This was unknown in ancient times when religions devised virgin births for their prophets and demonstrates how wrong these prinsiples are. To clarify this further a normal cell has 46 chromosomes while a gamete, the ova or sperm, has only 23. Before life can begin the new cell must acquire the extra 23 chromosomes to create an individual.
If an X and Y chromosome come together then the offspring is male, whereas if an X and X chromosome appear then the offspring is female. There is some debate over how much material the Y chromosome carries as some believe it is lacking some traits that the X chromosome has. But this is contentious as human father's pass on to son's specific traits, the most famous of which are big ears, color blindness and even smelly feet.
It is the random mating of all genes that produces the characteristic DNA which, like fingerprints, is not the same in any 2 individuals. It is like fingerprints a marker that cannot be mistaken.
Sex and Genes - X and Y Chromosomes
The Effects of Recessive Genes
Prominent in Some Societies
In isolated groups where marriage between cousins is normal there is often to be seen traits not normally found in the wider human population. These can include things like lack of pigmentation in eyes, skin and hair color, for example. We call these individuals albino.
Hemophilia is another trait related to recessive genes. It was a condition in many royal houses where cousins married each other to retain power and control. The Russian Royal Family suffered from this condition which may have come from Queen Victoria who was a carrier. She passed the condition to two of her daughters, one of whom was married to the Tsar of Russia, and one of her sons, Alexi. It means that the blood lacks the ability to clot due to the missing Factor VIII, a condition that he inherited this from his mother.
Huntington's Disease is another recessive genetic trait. It usually manifests itself after the age of 30 and causes a progressive destruction of brain cells. If present in a parent 50% of the offspring will inherit the disease unless there are other factors involved.
One of the diseases I studied and will talk about in another lens is Sickle cell anemia. This can be fatal at any age and death may occur as a result of a lack of oxygen and the sickling of blood cells. This can be brought on by sudden shock, elevation into thin air, and other things. There is usually no warning beforehand.
This is only a brief look at some of the recessive factors and their effects. But there are many others that can be studied by the enthusiast.
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