Molecular Basis of Inheritance: Simplifying NEET Preparation
Biology is the primary subject in NEET, which is why your preparations must be perfect for its various topics. Following the important notes of biology for NEET molecular basis of inheritance is crucial when it comes to understanding the basics of DNA and RNA. Basically, this topic highlights how certain characteristics are passed from generation to generation among human beings.
However, before proceeding to the molecular basis of inheritance NEET notes, let us learn a bit more about nucleotide, RNA and DNA, including the basic difference between the latter two.
What are RNA and DNA?
RNA (Ribonucleic Acid) and DNA (Deoxyribonucleic Acid) are the two primary building blocks. Both of these act as a store for genetic materials, although DNA is more common. Listed below are some of the differences between DNA and RNA, which can promote better understanding of them.
DNA’s Double Helix Structure
The Important notes of biology for NEET molecular basis of inheritance are incomplete without a reference to the characteristics of the double-helix model for DNA. Here is what you need to know about it.
Crick and Watson were the two scientists who proposed this revolutionary double helix model for DNA in 1953.
Later, scientist Ervin Chagraff postulated that the ratio of Cytosine and Guanine to Thymine and Adenine is always constant, and is equal to one.
DNA contains two polypeptide chains, with opposing polarity.
The nitrogen base of each chain combines with hydrogen to form the base pair or bp.
Pyrimidine base of one nucleotide chain always maintains a connection with the purine base chain of another nucleotide.
Similarly, Thymine always links with Adenine only.
Molecular basis of inheritance class 12 notes rightly explains that DNA replication is a process by which genetic materials from nucleic acid compounds are transferred into proteins. The amount of genetic data through such replication remains constant between the parent and progeny cells after mitosis.
Some of its Features Include
Replication origin is the source from which this process begins.
Deoxyribonucleoside triphosphate performs two vital functions here, namely, it acts as a substrate and it provides energy for the polymerisation to occur.
The DNA structure undergoes a mild change, leading to the formation of a replication fork. This acts as a site for replication.
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The above diagram shows the process of replication occurring in DNA. Studying the same should help you understand this procedure easily.
Transcription is the process during which information from the DNA is transferred to the RNA. However, only a single segment from the former is transferred. Here are some salient features of transcription –
DNA transcription involves three regions, namely, a terminator, a structural gene and a promoter.
Keep in mind that in RNA, Adenine cannot pair with Thymine, but instead links with Uracil.
Transcription process in bacteria is quite distinct from transcription in other living organisms. For bacteria, mRNA cytosol and nucleus are fused together, which means that there is no need for further processing.
Differences Between RNA Transcription and DNA Replication
A part of the important notes of biology for NEET molecular basis of inheritance is the distinction between DNA replication and RNA transcription. The table below provides all relevant information in this regard.
Apart from the replication and transcription, cells also undergo translation. Translation is the process using which amino acid polymerisation occurs. All three RNAs, namely tRNA, mRNA and rRNA, perform crucial roles in this translation procedure.