DNA, Genes and Chromosomes are the building blocks of inheritance. Your genes are what makes you who you are. And genes are made of DNA and are possess a specific location on a chromosome called gene locus. Given below is a detailed description of DNA, genes, and Chromosomes.
What is DNA?
DNA or Deoxyribonucleic Acid is the hereditary material in all living organisms, which contains the instructions needed by an organism to develop, live and reproduce. DNA is present on the chromosomes in the nucleus of a cell. Every cell in a person’s body has the same DNA. Most of the DNA is found in the nucleus of the cell however, a small amount is also found in the mitochondria of the cell, where it is called mitochondrial DNA or mtDNA.
DNA is made up small units called nucleotides. Each nucleotide consists of a phosphate group, a nitrogenous base, and a sugar group. Nitrogenous bases are of four type: Adenine (A), Guanine (G), Cytosine (C) and Thymine (T). The order of these bases in the DNA forms genes.
Nucleotides in the DNA are attached together to form a double-helix structure. The bases in one strand with the bases in the other strand. Adenine pairs with Thymine while Guanine pairs with Cytosine. Bases are joined together with hydrogen bonds. DNA can replicate and make copies of itself before cell division.
What are Genes?
(Do you know the difference between Gene and Allele?)
Genes are the basic physical and functional units of heredity. Genes are made up of DNA and give instructions to make specific kind of proteins. Genes vary in size from a few hundred to more than two million bases. All life forms are dependent on genes for survival and well-being. Every person has two copies each gene from which one is inherited from the mother and one from the father. Most of the genes are the same in every person but only about 1 percent may be slightly different in among individuals, which contribute to the unique characteristics of a person. The DNA in each chromosome contains many genes.
What are Chromosomes?
Chromosomes are thread-like structures that carry information for each and every characteristic that an individual possesses. These thread-like structures are actually made up of DNA. Every chromosome is made up of DNA tightly coiled around histone proteins. Every species has a specific number of chromosomes in their nucleus. Humans have 46 chromosomes in the form of 23 pairs.
Chromosomes are invisible under the microscope if a cell is in the non-dividing state. However, during cell division, they are tightly coiled so become visible under the microscope.
There is a constriction point in each chromosome called centromere which divides the chromosomes into two arms. Each chromosome has a short arm called “p arm” and a long arm called “q arm”.
Difference between DNA, Genes and Chromosomes
DNA is the hereditary material in all living organisms, which contains the instructions needed by an organism to develop, live and reproduce. Chromosomes are threadlike structures made up of DNA that carry information for each and every characteristic individual possesses. Chromosomes are found in the nucleus of the cell. Chromosomes contain many genes. Genes are the basic physical and functional units of heredity. Genes give instructions to make specific kind of proteins and vary in size from a few hundred to more than two million bases.