Genetic information, flow

The central dogma of molecular biology states that genetic information flows from genes, via RNA, to proteins. In this flow of information, messenger RNA (mRNA) is generated in a process called transcription and is subsequently processed to yield a mature transcript. The transcriptome is the combined set of aU transcripts present in a cell at a certain time, but it should be noted that mRNA is only a minor component of the entire... 

Genetic information flows from DNA to RNA to protein. DNA encodes the information required for synthesis of proteins and a copy of the encoded information is transcribed and processed into messenger RNA (mRNA). The information carried by the mRNA directs the synthesis of proteins, this process is called translation. Translation takes place on the surface of particles called ribosome s. 

The coding and replication of genetic information are some of the most important topics in biochemistry, and their study involves many of the concepts introduced in this chapter life, biomolecules, chemical reactions, energetics. In this final section of the first chapter we present a brief overview of the genetic aspects of biochemistry (also known as molecular biology). The material in this overview will help place the material in Chapters 2 through 16 in perspective. Genetic information flow is the subject of the final three chapters of the book. 

Under most circumstances genetic information flows from DNA (a) to RNA (b) to protein (c). DNA stores information that directs the synthesis of itself and the RNA molecules involved in protein synthesis. An important exception to the central dogma is the capacity of a small group of viruses, called the retroviruses, to synthesize DNA using an RNA template. 

In genetic information flow the shape and chemical properties of the bases in the nucleotide residues of DNA direct the assembly of polypeptides from amino acids. There are two phases of gene expression transcription and translation. In transcription, RNA polymerases use the capacity of nucleotide bases to form base pairs to copy the base sequence of genes to synthesize RNA molecules. During translation, ribosomes use the base sequence information in mRNA to construct polypeptides. 

Certain diseases such as acquired immunodeficiency syndrome (AIDS) and herpes are caused by retroviruses. The genetic information of a retrovirus is contained in its RNA. The retrovims uses the sequence of bases in RNA as a template to synthesize DNA. It is called a retrovirus because its genetic information flows from RNA to DNA instead of the more typical flow from DNA to RNA. 

Another important class of RNA virus comprises the retroviruses, so called because the genetic information flows from RNA to DNA rather than from DNA to RNA. This class includes human immunodeficiency virus 1 (HIV-1), the cause of AIDS, as well as a number of RNA viruses that produce tumors in susceptible animals. Retrovirus particles contain two copies of a single-stranded RNA molecule. On entering the cell, the RNA is copied into DNA through the action of a viral enzyme called reverse transcriptase (Figure 5.23). The resulting double-helical DNA version of the viral... 

From the following nucleic acids, select those that appear during the infection of a cell "with a retrovirus, for example, the AIDS virus, and place them in the order in which genetic information flows during the process of forming a new progeny virus. 

Soon after the Watson—Crick hypothesis was published, scientists began to extend it to yield what Crick called the central dogma of molecular genetics. This dogma stated that genetic information flows as follows ... 

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