Genes contain an infinite number of mysteries that still need to be unraveled. Scientists around the world find it fascinating to search for genes to reveal the past and the future. Genetic studies unravel its ancestral history, as well as the most likely diseases. But what is a gene? How are genes defined? Learn about genetic makeup, genetic definition, makeup, disorders, and much more.
What is a gene?
It is essential to quickly review the concept of cell so that you can fully understand what a gene is. Cells are the building blocks of life, the structural and functional unit of all living things. On average, human cells are too small to see with the naked eye, and a human body has up to 37.2 trillion cells. Some common examples of human cells that you might have found are red blood cells, eggs, sperm, and neurons, among others.
The longest cell in the human body is theneuron/nerve cell.
The largest cell in the human body is the egg.
The smallest cell in the human body is the spermatozoon and the cerebellar granule cell.
Inside a cell is the nucleus, and inside the nucleus are the chromosomes. Small structures called genes are found on chromosomes. So what is a gene?
gene definition: A gene is a short strand of DNA. It is a hereditary unit of information.
gene location: A gene is located at a locus (plural loci). It is a specific position of a gene or a gene marker on a chromosome.
The genetic diagram below shows the location and structure of genes.
Genes serve as instruction manuals and live inside the cells of your body. Each gene carries instructions that influence your traits/characteristics, such as color, height, earlobe, hair color, and more. In addition, there are different versions of genes for each character/trait. Each descendant inherits one version. But what are the versions of these genes?
Gene vs. Alleles
What are alleles? An allele is the variant form of a gene. Each gene is present at a specific locus in two copies/versions, where one copy of the gene is inherited from each parent. When the two copies are not the same, they are called alleles. Therefore, alleles represent alternatives for a character/trait.
An allele can be understood with the help of the following example:
Genes determine the color of your eyes. Thus, one allele/variant/version of a gene contains instructions for blue eyes, while another allele/variant/version of a gene contains instructions for black eyes.
A gene can have more than two alleles, but only two are present at a locus.
Wilhelm Johannes, a Danish botanist, coined the term gene in 1909.
dominant and recessive alleles: alleles can result in different phenotypes, since certain alleles are dominant over others. A dominant allele of a gene is always expressed independently of the other allele present and decides the phenotype. Alleles that remain suppressed in the presence of the dominant allele are called recessive. They are expressed only in homozygous conditions.
Homozygous and heterozygous: Each individual has two versions/alleles or a single gene. When the alleles are the same, the condition is called homozygous and the individuals are called homozygous. When the alleles are different, they are heterozygous.
Under some conditions, multiple alleles are codominant, that is, both are dominant and express each other. For example, the ABO human blood group system. An individual with type AB blood has one allele for A and one for B.
Structure and composition of genes
What are genes made of? Genes comprise deoxyribonucleic acid (DNA), except in some viruses that have ribonucleic acid (RNA). DNA consists of two strands of nucleotides twisted together, resembling a twisted ladder. Since a gene is a small section of DNA. It is made up of small chemicals called nitrogenous bases. Human genes vary in size from a million bases to a few hundred. Nitrogenous bases come in four types:
It is important to note that in some genes all the DNA sequences do not code. The non-coding sections of the DNA/RNA transcript are called introns. These introns are cut prior to protein synthesis. The coding sections of DNA (or RNA) are called exons.
Gen x ADN
DNA is the genetic material that carries information about heredity, mutations, the replication process, and the distribution of DNA in cell division. Genes are pieces of DNA that code for specific proteins and regulate the characteristics of an organism.
The following table lists the main differences between genes and DNA.
|Gene||DNA- Deoxyribonucleic acid|
|It is a stretch of DNA responsible for encoding specific proteins.||It is a biomolecule that contains genetic information.|
|Genes regulate the characteristics of an organism.||DNA regulates the regulation of genes.|
|It is a specific sequence in a short DNA.||They are two long chains of intertwined polynucleotides.|
|It is made up of DNA or RNA.||It is made up of nucleotides.|
|It is present on a chromosome.||It is present in the nucleus of the cell.|
Gene Functions: What do genes do?
- Genes control the functions of DNA and RNA.
- They form proteins that act as building blocks for muscles, skin, and connective tissue.
- They regulate the production of enzymes.
- Protein synthesis is responsible for almost all activities and is mainly controlled by genes.
- They contain a set of instructions that control functions.
- They pass information from parents to children.
Where do you get your genes?
You inherit genes from your parents. You get half from your mother and half from your father because you get 23 chromosomes from each parent.
When you inherit genes, you usually get two variations of each gene, one from each parent. For example, you inherit two versions of the genes that decide the color of your eyes. So if you inherit brown eye genes from your mother and blue eye genes from your father, you will have brown eyes because brown eye genes are dominant over blue eye genes.
But what makes you different from your siblings when you share the same parents?
The science of genes is fascinating. It is worth knowing that no one in the world can have the same genes as you unless they are your identical twin. So what makes you different from your siblings is the set of genes that you inherit from your parents, because each of your parents has two versions of each gene. So when they pass their genes to you, only one version is transferred, and the process is completely random.
Genetic disorders: how do genes affect your health?
Conditions or disorders that you inherit from your parents are genetic conditions. These conditions often run in families. There are more than 10,000 identified genetic conditions. A common genetic condition is sickle cell anemia. In this genetic disorder, the gene causes red blood cells to be the wrong shape (sickle-shaped), making it difficult for them to carry oxygen throughout the body.
Scientific research has shown that genes influence the risk of developing diseases such as diabetes, cancer, Alzheimer's and more.
There are generally three different ways that genetic disorders arise:
- a genetic change that occurs spontaneously in the process of formation or conception of the egg/sperm
- an altered gene that is passed from parent to child that leads to a disorder at birth or later in life
- an altered gene passed from parent to child causes genetic susceptibility to a disorder. This means that you are at higher risk of developing the disease when exposed to certain environmental or chemical factors. If you are not exposed, the condition may never develop.
Q1. What is gene therapy?
Gene therapy is a treatment option in which genetic engineering is used to treat a disease caused by a gene. It is about modifying the genes of an individual to cure a disease. Often, a disease-causing gene is replaced with a healthy copy of the same gene, or the disease-causing gene is turned off.
Q2. What is genetic counselling?
Genetic counseling is a process in which a genetic counselor provides information about possible genetic conditions that may affect you or your family based on your genetic makeup and family health history.
Q3. Who introduced the genes?
Gregor Mendel introduced the concept of genes, but later called them genetic factors. Later, Wilhelm Johannsen suggested the term genes for Mendelian hereditary factors. The word gene comes from the Greek where the word "genos" means birth.
Q4. What is a cistron?
A cistron is a short segment of DNA equivalent to a gene that specifies a single functional unit. It is the smallest unit of genetic material that encodes a single polypeptide in protein synthesis.
Genes serve as blueprints for our bodies. They carry important instructions, and when a gene changes, so does the message. Changes can also occur spontaneously in genes. Unwanted gene changes can also cause a wide range of disorders. Scientists have devised ways in which a correct gene can replace the incorrect one and solve the problem.