Session 12 (DNA to Protein)

Session 12 (DNA to Protein) - MCB 181 Study Session 12 (DNA...

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MCB 181 Study Session 12 (DNA to Protein)
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Learning Goals for Study Session 12 (DNA to Protein) Be able to describe the central dogma of molecular biology and clearly distinguish between the roles of transcription and translation in how cells utilize information stored in genes. Briefly describe the role of a promoter DNA sequence in the process of transcription. Be able to describe the functions of mRNA, rRNA, and tRNA in protein synthesis and describe the key structural features of tRNA. Understand the sequence of events that occurs during the process of protein synthesis and, given the genetic code, be able to translate an mRNA into a sequence of amino acids. Be able to provide a general explanation of how newly synthesized proteins are targeted to specific locations in the cell. Define the terms somatic, germ line, spontaneous, induced, point and chromosomal mutations. Be able to describe the different types of point and chromosomal mutations. Briefly describe the role of mutation in the creation of genetic variation.
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From Gene to Protein: Genotype to Phenotype A gene is a transcribed DNA nucleotide sequence (plus associated sequences regulating transcription) that usually codes for a protein (polypeptide) with a specific cellular function. Most proteins are either enzymes or have other functions that lead to a specific phenotype. Organisms control which genes are expressed to bring about developmental or environmental responses. Transcription refers to the process of copying the nucleotide sequence in DNA by synthesis of RNA. Translation refers to converting the genetic code in RNA to an amino acid sequence of a protein. A mutation is a heritable change in DNA that leads to an altered protein or gene product. In this study session we consider the transcription of DNA and how the RNA transcript is used to specify the primary amino acid sequence of a protein. We also describe how changes in DNA (mutation) can lead to an alteration of the protein produced from a gene.
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Transcription of a gene is the first step in converting information in DNA to a functional protein! To initiate transcription, the RNA polymerase binds to a promoter sequence on the DNA and begins to make an RNA transcript that is complementary to the template strand of the double stranded DNA (gene). The promoter DNA sequence stipulates where to start transcription and which strand to transcribe. RNA synthesis proceeds 5’ to 3’ as RNA polymerase adds the complementary ribonucleotides (ATP, UTP, CTP, and GTP) to the 3’ hydroxyl end of the elongating polynucleotide strand. Like DNA replication (Study Session 11), pyrophosphate is released from each nucleoside triphosphate as they are added to the elongating RNA transcript.
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Transcription of a gene ends when the polymerase reads the termination sequence on the gene! When the RNA polymerase reaches the termination sequence on
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Session 12 (DNA to Protein) - MCB 181 Study Session 12 (DNA...

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