What Is Genes and Its Function

  • In this what is genes and its function post we have briefly explained about definition, history of genes, work mechanism, composition, structure of genes, introns and exons, and characteristics.

What Is Genes and Its Function

  • Genes is a short section or segment of DNA which itself is made of millions of chemicals called nitrogenous bases. These bases are of four types; Adenine (A), Cytosine (C), Thymine (T), and Guanine (G).

Definition

  • A gene is a DNA segment or small portion. Adenine (A), Cytosine (C), Thymine (T), and Guanine (G) are the bases that make up DNA, which is a double-stranded molecule (G).
  • As a result, we may define a gene as a specific sequence of bases and a unit of genetic material (DNA) that can code for protein synthesis as well as ribosomal RNA, transfer RNA, and other RNA synthesis.
  • Genes have the ability to replicate and cross across, as well as undergo mutation. As a result, it is the DNA or chromosome’s functional unit.
  • They produce proteins, which form cells, and cells, in turn, form the body. The size of a gene might vary. Some genes in humans, for example, are made up of a few hundred DNA bases, while others have over 2 million.

History of genes

  • It was the Mendel who first discovered the concept of the inheritance of traits from parents to offspring, however, he failed to describe it or find out the role of genes.
  • Later, Wilhelm Johannsen coined the term ‘gene’ to represent the units of inheritance of Mendel. However, he was not able to describe the chemical structure of it. Later, in 1953, James Watson and Francis Crick defined the chemical structure of DNA that is a gene.

Work Mechanism

  • Each gene is made up of a specific base sequence that holds the information (code) needed to make specific proteins and so perform specified functions. They may, for example, provide instructions for a person’s eye colour, hair colour, skin colour, body height, and other characteristics.
  • Each gene is made up of a specific base sequence that holds the information (code) needed to make specific proteins and so perform specified functions. They may, for example, provide instructions for a person’s eye colour, hair colour, skin colour, body height, and other characteristics.
  • Similarly, cells use the genes that include keratin instruction to produce keratin protein. Keratin is a protein that can bind together to form hair and fingernails in the human body.
  • As a result, different cells use different genes to create the body and to cause it to perform various functions such as digestion, respiration, energy production, growth and development, and so on.
  • As a result, we can say that genes are the fundamental physical and functional unit of heredity, as they transport the information needed to specify traits or features from parents to children.

Composition

  • Gene is a short section or segment of DNA which itself is made of millions of chemicals called nitrogenous bases. These bases are of four types; Adenine (A), Cytosine (C), Thymine (T), and Guanine (G).
  • As the gene is a section of DNA, so each gene is made of a specific sequence of these four bases. Each base is a component of a nucleotide, which is a building block of DNA.
  • So, we can say that genes are made of four types of nucleotides A, T, G and C. Different genes have a different combination of nucleotides.
  • The nucleotides of one strand are connected to the nucleotides of opposite strand by hydrogen bonds, whereas, the nucleotides of a single strand are bonded with each other through phosphodiester bonds.
  • Different combination of bases of different nucleotides give a person different features, for example, a person with a combination of ATCGAT may have brown eyes and a person with ATCGAA may have blue eyes.
  • A human cell has around 20000 genes and 3,000,000,000 bases. The total number of genes and bases in a cell of an organism is called genome of an organism.

Structure of Genes

  • A gene is a short segment of DNA strand (a chain made of nucleotides). So, the entire DNA is a chain of genes or we can say that genes are units of DNA strands. The genes may vary in size based on the size of proteins for which they code.
  • There are three important parts or segments in the structure of a gene. The first region is the promoter, the second region is structural and the third or last region is the terminator.
Genes

What Is Genes and Its Function

Promoter region

  • There are some regions on DNA or gene that contain certain sequences that provide the signal to enzymes about the start point of a gene from where enzymes are supposed to start transcription.
  • These sequences which promote transcription are called promoter sequences and the region containing theses sequences is called Promoter region.
  • For example, in eukaryotes, the sequence in the promoter region is called TATA box as it is made of TATAAA base sequences.

Structural region

  • The structural region of a gene is the section of a gene that is transcripted to generate mRNA, or the part of a gene that includes the actual code that forms mRNA.

Terminator region

  • The terminator region is where the gene ends and contains a stop codon that signals the end of the transcription process. As a result, all areas of a DNA or gene do not act as genes or are not transcribed, but they do play a supporting role in transcription.

Introns and Exons

  • The main distinction between prokaryotic and eukaryotic genes is that prokaryotic genes only have exons, while eukaryotic genes have both exons and introns. So, prokaryotic genes are made of only exons.
  • Aside from that, an exon is a section or region of a gene that codes for protein production in the structural region. The intron, on the other hand, is the structural portion of a gene that does not participate in protein synthesis. Exons are coding regions, while introns are non-coding regions.
  • Exons are separated by introns. Splicing is the process of removing them from the freshly produced mRNA. Exons come together after introns are eliminated to generate a protein-coding sequence that is sent to ribosomes for protein production.
  • Exons are the bits of a gene’s coding sequence that survive splicing and remain in mRNA. During RNA processing, introns are spliced out.

Characteristics

  1. They are functional units of inheritance, variations, mutation and evolution. They determine the physical, mental and physiological features of a person and other organisms. They transfer these features form parents to their offspring.
  2. They are located in the chromosomes in the form of small segments of DNA. A gene occupies a fixed position in a DNA or chromosome. This position is known as a locus.
  3. The genes are arranged in a linear order one after another as beads on a string. They contain code or information for the synthesis of proteins, enzymes and RNAs that are needed to perform various functions in the body.
  4. They can make a duplicate copy of themselves through a process called replication. A single gene generally has two different forms called alleles.

What Is Genes and Its Function

  1. Genes enable parents to pass their features to their offspring. They carry the information related to traits or features of a person and when they are passed from one generation to another the information is also transferred.
  2. They control or determine the phenotype of the offspring including structural and functional features. They control reproduction through their replication.
  3. They may undergo mutations and cause polymorphism and variations in humans or a species. These mutations also cause metabolic disorders and inborn errors of metabolism.
  4. They are also associated with the aging process. They regulate the transcription of mRNA and thus control the amount of protein to be synthesized. They control the functions of DNA and RNA.
  5. They code for various types of RNAs other than mRNA such as rRNA and tRNA. They can switch on or off specific genes based on the requirements of an organism. They carry out cellular differentiation during development.

Further Readings

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