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23 lis 2024 · Key Points. Genes are composed of DNA arranged on chromosomes. Some genes encode structural or regulatory RNAs. Other genes encode proteins. Replication copies DNA; transcription uses DNA to make complementary RNAs; translation uses mRNAs to make proteins.
Genes are not linear sequences of DNA that directly correspond one-to-one with their protein counterparts. Moreover, scientists now know that not all transcribed RNA molecules, or...
The Rous sarcoma virus genome contains a mutated form of this gene, v-src, which produces a protein that is always activated. Infections of chickens with this virus cause cancers to develop. What type of gene is c-src?
The flow of genetic information in cells from DNA to mRNA to protein is described by the Central Dogma of molecular biology (Figure 16.2). When a cell needs a particular protein, the gene that codes for that protein is activated and a single-stranded mRNA copy is made of the gene, in a process called transcription.
Genes are used to make mRNA by the process of transcription; mRNA is used to synthesize proteins by the process of translation. The genetic code is degenerate because 64 triplet codons in mRNA specify only 20 amino acids and three nonsense codons.
Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated into viral proteins by the host cell's ribosomes.
23 lis 2024 · Positive sense, negative sense, double stranded viruses, and retroviruses are RNA viruses with different modes of replication. Positive-sense ssRNA viruses (Group IV) have their genome directly utilized as if it were mRNA. Replication of viruses involves primarily multiplication of the genome.
