Molecular basis of inheritance

Molecular Basis of Inheritance

Edited By Team Careers360 | Updated on May 10, 2022 03:18 PM IST

DNA and RNA are the essential genetic components and are responsible for passing genes from the parents to the offspring. Various traits are inherited from one generation to the next where diversity arises as a result of 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. Alternatively there are viruses in which RNA is genetic.

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It is often difficult to find suitable notes for this article; Don't worry! Here, we give you a brief understanding of the basics associated with molecular inheritance.

Why DNA Is Important to the Molecular Foundation of Inheritance?

If we see a cell under a microscope, we can see a nucleus, which is a region that contains all the genes. The nucleus contains the nucleolus and chromatin which are cord-like structures. Chromatin thickens to form chromosomes where the genes are found. Each chromosome contains thousands of genes, and each gene identifies a specific trait. The number of chromosomes within each living cell is determined, for example, humans have 23 pairs of homologous chromosomes i.e. 46 by number. On the other hand, the number of genes in each chromosome is huge, reaching thousands. In different species, the chromosome number may vary.

Gene is made up of a double-stranded structure called DNA; Different parts of DNA are responsible for various factors such as skin color, hair color, eye color, etc. This means that DNA is largely responsible for the inheritance of cells.

DNA and RNA structure

Nucleic Acids

A group of biomolecules contains two types of nucleic acids, including DNA and RNA, which play a vital role in the cellular gene.

DNA is Deoxyribonucleic acid and a helical structure with double strands, like a ribbon wrapped around each other. It is a polynucleotide or polymer (small molecules - many monomers combine to form polymers). Here, monomer units are deoxyribonucleotides and the length of DNA is determined by the number of nucleotides.

RNA is Ribonucleic acid and its structure is similar to the structure of DNA but contains one strand. A polymer or polynucleotide, composed of several monomer units is called ribonucleotides. RNA is the basis of the cell gene for a number of viruses.

Any Nucleotide present in DNA or RNA has three components:

Pentose sugar
Nitrogen base
Phosphate group

Pentose Sugar- A monosaccharide containing 5 carbon atoms. RNA contains ribose sugar and DNA contains deoxyribose sugar (by the release of one oxygen molecule).

Phosphate Group- It is usually a phosphorus salt and also a pentose sugar. The phosphate group forms the backbone of the given polynucleotide chain.

Nitrogenous Base- A compound that contains nitrogen with basic properties. Two types of nitrogenous foundations are purines and pyrimidines. Purines is a fragrant heterocyclic compound (atoms from two different compounds with one double bond) and 9-member bracelets with a dual ring system. Adenine and Guanine are examples of Purines. Pyrimidines also have a similar structure to purines with 6-member rings and a single ring system.

The examples of pyrimidine are Cytosine, Uracil and Thymine. Depending on the structure of DNA or RNA, certain nitrogenous bases are present. Uracil exists only in RNA, not in DNA and Thymine is only in DNA and not in RNA.

How Is Polynucleotide Made By Joining Nucleotides?

The N-glycosidic bond binds to the nitrogenous base and pentose sugar and forms 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.

DNA and its polynucleotide chain

Phosphate, pentose sugar and nitrogen bases comprising A, T, G or C are present in its polynucleotide series. The phosphate groups are attached to the sugar nucleotide molecule followed by phosphodiester bonds, this is how the whole polynucleotide chain is formed. This series has two free endings namely 5 'phosphate end and 3' hydroxyl end. The first one is called 5 prime ends and the last one is called 3 prime ends.

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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, red and blue shown below in the diagram. Sugar and phosphate form the backbone of the helix structure. Nitrogen bases are internal components and are bound by hydrogen bonds. Containing a compatible base pair, Adenine will always be compatible with Thymine and double bond and Guanine will always be compatible with Cytosine with a triple bond. There is a similar distance between the two helix fibers since the pairing occurs between one purine and one pyrimidine.

Two polynucleotide chains have antiparallel polarity, i.e. a 5 'end with a single phosphate free single band paired with a 3' end and a free hydroxyl group of another parallel strand. The two chains are tied in the form of the right hand on the helix. The diameter of a single helix called a helix pitch is 3.4 nm and there are 10 basic pairs per turn.

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Genetic Code

It is a set of rules in which coded information within DNA or mRNA sequences is translated into proteins by living cells.

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.

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Frequently Asked Questions (FAQs)

1. What is the Meaning of Frameshift Conversion?

Any unexpected gain or loss in one or two foundation pairs changes the learning framework. This condition is called a frameshift mutation.

2. Why and when was the Human Genome Project Launched?

The Human Genome Project was launched in 1990. Its primary objective was to define the complete sequence of human DNA. To do this, genetic engineering and other advanced techniques are used.

3. What is Central Dogma in Molecular Biology?

Central Dogma refers to the transfer of genetic information from DNA to RNA, and eventually to proteins. Therefore, this process is known as Central Dogma in molecular biology. Francis Crick was the first scientist to speculate on such a theory.

4. What is Central Dogma?

The formation of protein or protein synthesis begins in DNA. The process of replication helps to make multiple copies of DNA. A single strand of DNA is copied to form mRNA and the process is called transcription. Now, during translation, all kinds of non-genetic RNAs- rRNA, tRNA and mRNA form proteins. This is called the Central dogma theory developed by biologist ‘Francis Harry Compton’ in which he states that biological knowledge flows in a single pattern.

DNA → RNA → Proteins

5. What Is a molecular basis of inheritance?

DNA, called the genetic molecule and RNA, are two components that make up the basis. It allows living things to receive genetic information from the parents' genes. The genes are then reproduced and transmitted to the reproductive cell from the parent cell in each cell division.