Molecular genetics mRNAs

The central dogma of molecular genetics describes how hereditary information is transmitted and used to synthesize proteins. The main features of this theory are shown in Fig. 21-7. DNA is the storage form of hereditary information. The hereditary information is the sequence of nucleotide residues in DNA which corresponds to a specific sequence of amino acid residues in a polypeptide. Replication is the process of copying DNA during cell division. Transcription is the synthesis of RNA from DNA, the first step in the transmission of hereditary information. Three types of RNA are produced, ribosomal RNA (rRNA), messenger RNA mRNA), and transfer RNA (tRNA). rRNA, mRNA, and tRNA participate in the process of translation—the synthesis of protein. 

Let us note, then, that mRNA can also be detected in higher plants and this finding helps to support the concept of molecular genetics. This mRNA is, in part, short-lived and, in part, long-lived too. 

Schoffl, F. Key, J.L. (1982). An analysis of mRNA s for a group of heat shock proteins of soybean using cloned cDNA s. Journal of Molecular and Applied Genetics, 1, 301-14. 

The anticodon region consists of seven nucleotides, and it recognizes the three-letter codon in mRNA (Figure 38-2). The sequence read from the 3 to 5 direction in that anticodon loop consists of a variable base-modified purine-XYZ-pyrimidine-pyrimidine-5h Note that this direction of reading the anticodon is 3 " to 5 whereas the genetic code in Table 38—1 is read 5 to 3 since the codon and the anticodon loop of the mRNA and tRNA molecules, respectively, are antipar-allel in their complementarity just like all other inter-molecular interactions between nucleic acid strands. 

Stochastic simulations confirm the existence of bifurcation values of the control parameters bounding a domain in which sustained oscillations occur. The effect of noise diminishes as the number of molecules increases. Only when the maximum numbers of molecules of mRNA and protein become smaller than a few tens does noise begin to obliterate the circadian rhythm. The robustness of circadian rhythms with respect to molecular noise is enhanced when the rate of binding of the repressor molecule to the gene promoter increases [128]. Conditions that enhance the resistance of genetic oscillators to random fluctuations have been investigated [130]. 

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