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Gene is the biological basis of life, i.e. life exists the way we know because of it. It is a segment of DNA that occupies a specific location on a chromosome. In other words, they are fragments of DNA carrying invaluable genetic information. A gene combines proteins made up of four nucleotides, namely Adenine, Cytosine, Thymine, and Guanine. Genes determine several physical traits of an individual and determine their health profile, i.e. what genetic disorders they would most likely develop. Your parents’ genes determine even your biological sex passed on.
Gene and its constitution
Genes are located inside the chromosome in the nucleus of a cell. Genes are small segments of DNA that are passed from parents to their offspring. To understand the constitution of genes, let’s know about DNA first.
DNA or deoxyribonucleic acid is a double helical structure composed of four nucleotides – Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Adenine base pairs with Thymine and Cytosine base pairs with Guanine to form the double strand of DNA.
Since genes are segments of DNA, they consist of the same thing. However, they can vary in size, i.e. from a mere hundred DNA base pairs to over a million base pairs in a gene. As a result, human beings have around 20-25 thousand genes that store genetic information in the body. Genes also instruct the body to make proteins, the essential biomolecules needed to perform several body functions.
Unique To Each Individual
Everyone has two copies of each gene, one inherited from their father and another from their mother. We have 46 chromosomes that account for 23 pairs. Out of these 23 pairs, 22 are autosomes that determine several body characteristics. The remaining pair is the sex chromosome or gonosome – XY in males and XX in females. The first X is inherited from the mother, i.e. it remains constant. The sperm, however, can have either Y or X chromosomes, which determines the biological gender of the child.
Genes are what give you your uniqueness. Human beings have most of the genes similar to each other, but the varying 1% genes are unique to you and are known as alleles.
Gregor Mendel discovered and explained the process of inheritance of genes.
Genetic Disorders
So far, we’ve studied that genes determine physical body characteristics. For example, your straight or curly hair, eye colour, blood type, and height are determined by your gene sequence. But, genes also determine what kind of diseases you are most likely to develop in your lifetime.
Sometimes, the gene you inherit from your parents can mutate and result in genetic disorders. When a gene changes its constitution due to certain factors, we say a mutation has occurred. Now, mutations can be inherited from either one or both parents and can also occur due to lifestyle.
Genes give out instructions to make proteins. Sometimes, due to these mutations, either the protein is formed faulty or not formed. As a result, it leads to dysfunction in the body, as each protein has an important role. The resulting disorders are called genetic disorders that can be of three types:
- Chromosomal disorders: The chromosome is where the genes are located, and when mutations occur in a chromosome, conditions like down syndrome can be inherited.
- Single-gene disorders: When one gene is mutated, we can get genetic conditions like sickle cell anaemia, in which the body cannot make proper functional haemoglobin.
- Complex disorders: When mutations occur in more than one gene, diseases like colon cancer can occur.
Gene Therapy
Gene therapy is a novel and advancing branch of medicine in which a mutated gene is replaced by a healthy gene. For example, in 2016, gene therapy was employed to improve the eyesight of three adults who have a genetic disorder called congenital blindness.
Researchers are in the process of finding a way to treat cancer using gene therapy. It would be a breakthrough in the medical community that can save millions of lives every year if that happens.
Gene Sequencing
Gene therapy is an ambitious science to treat disorders but to achieve that, it is crucial first to identify the sequence of bases in that specific gene. It is known as gene sequencing. The Human Genome Project is one of the most significant research projects in biological science, taken up in 1990 by the United States National Institutes of Health (NIH) and the Department of Energy. The project aimed to identify the sequence of all the genes that make up your body.
It was concluded in 2003 and allowed scientists to assemble the data and conduct future research. It also allowed for identifying over 1800 faulty genes that lead to genetic disorders in human beings.
Conclusion
Gene is the biological unit that determines a lot of our physical traits and is passed onto us from our parents. It is a fragment of DNA that is present in the nucleus of the cell. We have thousands of genes in the body that control our several aspects, including our health. If there is a mutation in the gene, then it may lead to genetic disorders like down syndrome, breast cancer, etc. Through gene sequencing, it is possible to determine the possible base pairs forming the DNA.
