Gene expression is the combined process of the transcription of a gene into mRNA, the processing of that mRNA, and its translation into protein (for protein-encoding genes). Significance of Gene Expression Regulated expression of genes is required for Adaptation, differentiation, and development, 1) Adaptation Organisms adapt to environmental changes by altering gene expression. a) Bacteria
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The pathway of protein synthesis is called Translation because the language of the nucleotide sequence on mRNA is translated into the language of an amino acid sequence. The process of Translation requires a Genetic code, through which the information contained in the nucleic acid sequence is expressed to produce a specific sequence of amino acids.
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A primary transcript is a linear copy of a transcriptional unit, the DNA segment between specific initiation and termination sequences. The primary transcript of both prokaryotic and eukaryotic tRNAs and rRNAs are post-transcriptionally modified by removing extra nucleotides. Transfer RNAs are then further modified to acquire special characters unique to tRNAs. In fact, many of
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The general transcription process can be applied to both prokaryotic and eukaryotic cells. The basic biochemistry for each is the same; however, the specific mechanisms and regulation of transcription differ between prokaryotes and eukaryotes. Transcription of eukaryotic genes is a far more complicated process than prokaryotes. The important points of differences are as follows: 1)
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RNA Synthesis The synthesis of an RNA molecule from DNA is called Transcription. All eukaryotic cells have five major classes of RNA: ribosomal RNA (rRNA), messenger RNA (mRNA), transfer RNA (tRNA), and small nuclear RNA and microRNA (snRNA and miRNA). The first three are involved in protein synthesis, while the small RNAs are involved in mRNA
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1. The following are all characteristics of the genetic code except: Universal Degenerate Non-overlapping Ambiguous 2. Which of the following statements is not true concerning the role of Aminoacyl t-RNA synthetases: Charging an aminoacyl t-RNA synthetase (loading) with an amino acid is an energetically favorable reaction. For every amino acid, there are several Aminoacyl t-RNA
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DNA in the living cell is subjected to many chemical alterations. If the genetic information encoded in the DNA is to remain uncorrupted, any chemical changes must be corrected. A failure to repair DNA produces a mutation. Agents that Damage DNA Radiations- Highly reactive oxygen radicals produced during normal cellular respiration as well as by other biochemical pathways Ionizing
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DNA Replication Basis for inheritance The fundamental process occurring in all cells for copying DNA to transfer the genetic information to daughter cells Each cell must replicate its DNA before division. Salient features of DNA replication 1) Semi-conservative Parental strands are not degraded Base pairing allows each strand to serve as a template for a
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DNA Replication: the process of DNA Synthesis Purpose of replication Basis for inheritance The fundamental process occurring in all cells for copying DNA to transfer the genetic information to daughter cells Each cell must replicate its DNA before division. Salient features of DNA replication 1) Semi conservative Parental strands are not degraded Base pairing allows
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RNA (Ribonucleic acid ) Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by 3′,5′-phosphodiester bridges analogous to those in DNA (Figure-1). Figure 1- Showing an RNA fragment, the ribonucleotides are linked together by 3′-5′ phosphodiester linkages. Ribose is the principal sugar in RNA Differences between RNA and DNA Although sharing
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