Molecular Basis of Inheritance

DNA and RNA are the essential genetic components responsible for passing genes from the parents to the offspring. Various traits are inherited from one generation to the next, where diversity arises due to recombination. Through many studies and studies, it has been found that the genetic makeup of most living organisms is called DNA (Deoxyribonucleic Acid) and is responsible for the transmission of signals from one species to another. The Molecular Basis of Inheritance is one of the most important topics in biology.

This Story also Contains

1. What is Inheritance in Biology?
2. Why is DNA important to the Molecular Basis of Inheritance?
3. DNA Vs RNA structure
4. How is Polynucleotide Made by Joining Nucleotides?
5. Double Helix DNA Structure
6. Human Genome Project
7. Gene Expression and Regulation
8. Central Dogma of Molecular Biology
9. Lac Operon

It is important to understand how the characteristics are passed down at the molecular level. Both DNA and RNA work as a blueprint for life. In this article, complete information about what inheritance is, why DNA is important in molecular biology, the structure of both DNA and RNA, the double helix structure of DNA, and the human genome project is given.

What is Inheritance in Biology?

Inheritance is the process by which characteristics are passed from parents to their offspring through genes. It explains how children inherit the physical features of their parents, like eye color, hair type, blood group, and certain human genetic disorders. This transfer of genetic information occurs through DNA, which is responsible for carrying the instructions for building and maintaining an organism.

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Why is DNA important to the Molecular Basis of Inheritance?

Gene is made up of a double-stranded structure called DNA; Different parts of DNA are responsible for various factors such as skin colour, hair colour, eye color, etc. This means that DNA is largely responsible for the inheritance of cells. Some of the major reasons why DNA is important to the Molecular Basis of Inheritance are mentioned below:

• The nucleus of a cell contains the nucleolus and chromatin. This is the place where all the genes are packed.

• Chromatin is condensed into chromosomes, where thousands of genes are responsible for certain traits.

• Every human being has 23 pairs of homologous chromosomes and a total of 46 pairs of chromosomes.

• Each pair of chromosomes contains thousands of genes that are responsible for deciding certain characteristics of your body as well as your personality.

• The number of chromosomes can vary from species to species.

DNA Vs RNA structure

It is important to understand the structure of DNA and RNA to understand how genetic information is stored and transmitted. While both of these molecules are nucleic acids and are made up of long chains of nucleotides, they still differ in structure, function, and chemical composition. Some basic structure of DNA and RNA is discussed below:

How is Polynucleotide Made by Joining Nucleotides?

The N-glycosidic bond binds to the nitrogenous base and pentose sugar, forming a nucleoside. The phosphate group connected to this nucleoside by phosphodiester linking forms the nucleotide. Many nucleotides combine to form polynucleotides using a 3’-5 ’phosphodiester bond. This is how nucleic acid chains form in DNA or RNA. The entire procedure of how polynucleotide is made by joining nucleotide together is discussed below:

• Each nucleotide consists of a pentose sugar-phosphate group and a nitrogenous base.

• These nucleotides are linked through a phosphodiester bond between the phosphate group of 1 nucleotide and the 3’ group of sugar in another nucleotide.

• This bond is formed using a sugar-phosphate backbone which is also supported by a nitrogenous base extending the sugar units.

• Repeating the center bonding process creates a long chain of nucleotides which forms a polynucleotide like DNA or RNA.

Double Helix DNA Structure

Watson and Crick proposed this DNA structure with a study based on X-ray DNA sequencing. It is made up of 2 polynucleotide chains, Sugar and phosphate form the backbone of the helix structure. Nitrogen bases are internal components and are bound by hydrogen bonds. Some more details about the structure of the Double Helix of DNA are discussed below:

• DNA consists of two strands of polynucleotides that are coiled with each other in a helical shape.

• Adenine is paired with Thymine, and Guanine is paired with Cytosine with hydrogen bonds.

• The two DNA strands are running opposite to each other, one from 5’ to 3’ and the other from 3’ to 5’.

• The outer structure of the helix is formed by the sugar-phosphate backbone and at the same time the nitrogenous bases are inward.

• The strands are twisted to form a right-hand helix.

• There are around 10 pairs per turn.

Human Genome Project

It was launched as an international scientific research project for determining the base pairs that make up human DNA. It includes identifying and mapping all the genes of the human genome in terms of physical features and functionalities. It has high importance in the fields of life science, medicine, and biotechnology. Basic facts about the Human Genome Project are mentioned below:

• The project was started in 1990 and was completed in 2003 which was ahead of schedule.

• It mapped around 3 billion DNA base pairs and has identified around 20,000 to 25,000 human genes.

• It was an international research initiative that involved scientists from multiple countries.

• The project has advanced an understanding of genetics that has led to the improvement of medicine, biotechnology, and disease research.

Gene Expression and Regulation

Gene expression is the process through which the information stored in DNA is converted into proteins. It usually involves two main stages: Transcription and translation. Understanding gene expression and regulation is important is understanding the results in diversity of life functions.

Transcription:

It is the process by which a segment of DNA is copied into messenger RNA.

Translation:

It is the process where the mRNA sequence is processed by a ribosome to assemble amino acids into a specific protein.

Central Dogma of Molecular Biology

The Central Dogma of Molecular Biology was first proposed by Francis Crick in 1958. He was among the co-discoverers of the structure of DNA. It explains the flow of genetic information and outlines how genes encoded in DNA are expressed through transcription and translation. The central dogma describes the following sequence:

DNA → RNA → Protein

Lac Operon

The Lac Operon is a gene regulatory system in bacteria that controls the breakdown of lactose. It is found in Escherichia coli and other bacteria. It is an example of an inducible operon. This means that is is normally off but can be turned on in the presence of an inducer.

It consists of three structural genes:

1. lacZ - It codes for β-galactosidase

2. lacY - encodes for permease

3. lacA - encodes for transacetylase

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