NCERT Book Class 12 Biology Chapter 5 Molecular Basis of Inheritance

CHAPTER 5

MOLECULAR BASIS OF
INHERITANCE

5.1 The DNA

5.2 The Search for Genetic
Material In the previous chapter, you have learnt the inheritance
patterns and the genetic basis of such patterns. At the
5.3 RNA World time of Mendel, the nature of those ‘factors’ regulating
5.4 Replication the pattern of inheritance was not clear. Over the next
hundred years, the nature of the putative genetic material
5.5 Transcription
was investigated culminating in the realisation that
5.6 Genetic Code DNA – deoxyribonucleic acid – is the genetic material, at
least for the majority of organisms. In class XI you have
5.7 Translation
learnt that nucleic acids are polymers of nucleotides.
5.8 Regulation of Gene Deoxyribonucleic acid (DNA) and ribonucleic acid
Expression (RNA) are the two types of nucleic acids found in living
5.9 Human Genome Project systems. DNA acts as the genetic material in most of the
organisms. RNA though it also acts as a genetic material
5.10 DNA Fingerprinting in some viruses, mostly functions as a messenger. RNA
has additional roles as well. It functions as adapter,
structural, and in some cases as a catalytic molecule. In
Class XI you have already learnt the structures of
nucleotides and the way these monomer units are linked
to form nucleic acid polymers. In this chapter we are going
to discuss the structure of DNA, its replication, the process
of making RNA from DNA (transcription), the genetic code
that determines the sequences of amino acids in proteins,
the process of protein synthesis (translation) and
elementary basis of their regulation. The determination