What is a Gene: Explanation, Location, Diagrams & Facts

A gene is a distinct stretch of DNA that determines something about who you are. Genes vary in size, from just a few thousand pairs of nucleotides. A gene is a sequence of DNA or RNA is which codes for a molecule that has a function. During gene expression, the DNA is first copied to RNA. A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes less than 1 percent of the total are slightly different between people. Alleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each person’s unique physical features.

Where are genes located?

Where are genes located

Genes are located on DNA present in the chromosome. Chromosomes are present in the nucleus of the cell. Genes are the sequence of DNA segments which are responsible for the production of certain proteins and traits within an organism. Chromosomes are the structures within the cell that carries the genetic information. Genes, DNA, and chromosomes all play an important role in shaping who are storing this genetic material.


Genes and chromosomes:

gene chromosome

Humans grow and develop based on the instructions contained in our genetic material. A normal human cell should contain exactly 46 chromosomes. They are matched into 23 pairs. Pairs one through 22 are numbered by size and appearance and are the same in males and females. The 23rd pair is referred to as the sex chromosomes. Typically, females have 2 X chromosomes, while males have an X and a Y. The shorthand way to refer to a normal set of chromosomes is 46, XX for women and 46, XY for men.


Structure of genes:

Structure of genes

Gene diagram:

Gene diagram

Gene facts:

Gene facts

  1. A gene is a small section of DNA that contains the instructions doe a specific molecule, usually a protein.
  2. The purpose of the gene is to store information.
  3. Each gene contains the information required to build specific proteins needed in an organism.
  4. The human genome contains 20,687 protein-coding genes.
  5. Genes come in different forms called alleles.
  6. In humans, alleles of particular genes come in pairs, one on each chromosome we have 23 pairs of chromosomes. If the alleles of a particular gene are the same, the organism is described as homozygous? for that gene. If they are different the organism is described as heterozygous for that gene.
  7. An individual’s phenotype? is determined by the combination of alleles they have.
  8. For example, for a gene that determines eye color, there may be several different alleles. One allele may result in blue eyes, while another might result in brown eyes. The final color of the individual’s eyes will depend on which alleles they have and how they interact.
  9. The characteristic associated with a certain allele can sometimes be dominant or recessive.

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