Molecular Basis of Inheritance

MOLECULAR BASIS OF INHERITANCE -1- Over the next hundred years, the nature of the putative genetic material was investigated culminating in the realisation that DNA – deoxyribonucleic acid – is the genetic material, at least for the majority of organisms.

Molecular Basis of Inheritance, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Master Table: Molecular Basis of Inheritance Topic Explanation Key Details MCQ Inheritance Patterns Factors regulating inheritance patterns were unclear in Mendel’s time but are now linked to genetic material (DNA/RNA). – DNA is the genetic material in most organisms.– RNA functions as a genetic material in some viruses and a messenger in others. Q: What […]

MOLECULAR BASIS OF INHERITANCE -1- Over the next hundred years, the nature of the putative genetic material was investigated culminating in the realisation that DNA – deoxyribonucleic acid – is the genetic material, at least for the majority of organisms. Read More »

During replication and transcription a nucleic acid was copied to form another nucleic acid. Hence, these processes are easy to conceptualise on the basis of complementarity. The process of translation requires transfer of genetic information from a polymer of nucleotides to synthesise a polymer of amino acids. Neither does any complementarity exist between nucleotides and amino acids, nor could any be drawn theoretically. There existed ample evidences, though, to support the notion that change in nucleic acids (genetic material) were responsible for change in amino acidsin proteins. This led to the proposition of a genetic code that could directthe sequence of amino acids during synthesis of proteins.

Molecular Basis of Inheritance, NCERT LINE BY LINE, pre-class / Prof. Siddharth Sanghvi

Concept Description Genetic Code The set of rules by which information encoded in genetic material is translated into proteins. Replication and Transcription Processes that involve copying a nucleic acid to form another nucleic acid based on complementarity. Translation Process requiring transfer of genetic information from nucleotides to synthesize a polymer of amino acids. Complementarity Exists

During replication and transcription a nucleic acid was copied to form another nucleic acid. Hence, these processes are easy to conceptualise on the basis of complementarity. The process of translation requires transfer of genetic information from a polymer of nucleotides to synthesise a polymer of amino acids. Neither does any complementarity exist between nucleotides and amino acids, nor could any be drawn theoretically. There existed ample evidences, though, to support the notion that change in nucleic acids (genetic material) were responsible for change in amino acidsin proteins. This led to the proposition of a genetic code that could directthe sequence of amino acids during synthesis of proteins. Read More »

The split-gene arrangements represent probably an ancientfeature of the genome. The presence of introns is reminiscent of antiquity,and the process of splicing represents the dominance of RNA-world. In recent times, the understanding of RNA and RNA-dependent processes in the living system have assumed more importance.

Molecular Basis of Inheritance, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Aspect Description Distinguishing RNA Subsets In early cells that lacked DNA, a crucial problem was differentiating between two types of RNAs: messenger RNAs (mRNAs) that code for proteins, and heritable genetic RNAs that propagate genetic information through generations. Role of Introns Scientists proposed that introns could serve as markers for these RNA subsets, directing them

The split-gene arrangements represent probably an ancientfeature of the genome. The presence of introns is reminiscent of antiquity,and the process of splicing represents the dominance of RNA-world. In recent times, the understanding of RNA and RNA-dependent processes in the living system have assumed more importance. Read More »

NCERT-NEET-An intriguing question is that how is the RNA polymerases able to catalyse all the three steps, which are initiation, elongation and termination. The RNA polymerase is only capable of catalysing the process of elongation. It associates transiently with initiation-factor (σ)and termination-factor (ρ) to initiate and terminate the transcription, respectively. Association with these factors alter the specificity of theRNA polymerase to either initiate or terminate

Molecular Basis of Inheritance, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Feature Description Definition The process of copying genetic information from one strand of DNA into RNA. Principle of Complementarity Follows the principle of complementarity where adenosine pairs with uracil instead of thymine. Strands Involved Only one strand of the DNA (template strand) is copied into RNA. The other strand is the coding strand. Transcription Unit

NCERT-NEET-An intriguing question is that how is the RNA polymerases able to catalyse all the three steps, which are initiation, elongation and termination. The RNA polymerase is only capable of catalysing the process of elongation. It associates transiently with initiation-factor (σ)and termination-factor (ρ) to initiate and terminate the transcription, respectively. Association with these factors alter the specificity of theRNA polymerase to either initiate or terminate Read More »

DNA Replication – The Machinery and the Enzymes -NCERT-NEET-‘‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material’’(Watson and Crick, 1953).

Molecular Basis of Inheritance, NCERT LINE BY LINE, pre-class / Prof. Siddharth Sanghvi

Step Enzymes Involved Details Prokaryotic vs Eukaryotic Differences Initiation Helicase, Primase Helicase unwinds the DNA helix at the origin of replication. Primase synthesizes RNA primers to provide a starting point for DNA synthesis. Replication occurs at the replication fork, a small opening in the DNA helix. Prokaryotes: Single origin of replication. Eukaryotes: Multiple origins of

DNA Replication – The Machinery and the Enzymes -NCERT-NEET-‘‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material’’(Watson and Crick, 1953). Read More »