PowerPoint PresentationDNA is the instructions (program) that tells the cell what to do. Proteins are the results of those instructions.Slide 3Step one - DNA to RNA-The RNA is complementary to the DNASlide 6Slide 7During transcription of a gene, only one strand (template strand) of the DNA’s two strands is read.Step two - RNA to proteinWhy is this process referred to as translation??Slide 11In the genetic code, a triplet of nucleotides specifies an amino acidThere are 4 nucleotides in RNA and 20 amino acids. -4 different nucleotides, combining as codons, which are 3-nucleotide sequences. Math would dictate that there could potentially be as many as 64 amino acids (43) But there are only 20, since each amino acid is usually encoded by more than one codon.60 of the 64 possible codons code for amino acids. The remaining four codons signal the translation to start (start codon) and translation to stop (stop codon). Since there are only 20 amino acids, more than one codon can code for the same amino acid. This relationship makes the code redundant, or degenerate.Slide 15Why are only 20 amino acids formed from the 64 possible combinations of the bases?Slide 17Slide 18Slide 19Slide 20Slide 21What is the order of steps in the transcription process?How does initiation begin?If the mRNA transcript AUGCGCUGCAAU were to leave the nucleus and undergo translation at a ribosome, what would be the sequence of anticodons translating this nucleotide into protein?Translation is the RNA-directed synthesis of proteins. During translation, proteins are synthesized according to the genetic message of sequential codons in the mRNA.Slide 26Slide 27Slide 28Slide 29Slide 30Where does protein synthesis occur?Slide 32Slide 33Slide 34Using this one codon => one anticodon => one amino acid method the gene is decoded to synthesize a protein.As in transcription, translation (protein synthesis) occurs in three stages:Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47---Mutations are permanent changes in the DNA that can involve large chromosomal regions or a single nucleotide pair.Slide 49Substitutions are the replacement of one base with anotherSlide 51Slide 52Chapter 12-Gene Expression and RegulationDNA is the instructions (program) that tells the cell what to do. Proteins are the results of those instructions.Fig. 12.2Step one - DNA to RNAThis process is called transcription.---Transcription is the synthesis of RNA using DNA as a templateDNA ==> RNA ==> Proteins-The RNA is complementary to the DNA-RNA that is synthesized from a gene coding for a protein is called messenger RNA (mRNA), or a transcriptDifferences between DNA and RNA:1. sugar - deoxyribose (DNA) verses ribose (RNA)2. base - thymine (DNA) is replaced by uracil (RNA)During transcription of a gene, only one strand (template strand) of the DNA’s two strands is read.Different genes use different strands as the template strand.Step two - RNA to proteinThis process is called translation.---Translation is the synthesis of a polypeptide (protein) directed by mRNAWhy is this process referred to as translation??Converting the language of nucleic acids into the language of proteins:•4 bases in nucleic acids•20 amino acids in proteins-transfer RNA (tRNA) and ribosomal RNA (rRNA) act as the "interpreter" between the nucleotide “language” of mRNA and the amino acid “language” of proteins.In the genetic code, a triplet of nucleotides specifies an amino acidThere are 4 nucleotides in RNA and 20 amino acids.-4 different nucleotides, combining as codons, which are 3-nucleotide sequences.Math would dictate that there could potentially be as many as 64 amino acids (43)But there are only 20, since each amino acid is usually encoded by more than one codon.60 of the 64 possible codons code for amino acids. The remaining four codons signal the translation to start (start codon) and translation to stop (stop codon).Since there are only 20 amino acids, more than one codon can code for the same amino acid. This relationship makes the code redundant, or degenerate.Table 12-3Why are only 20 amino acids formed from the 64 possible combinations of the bases?•1. All the combinations code for a different amino acid.•2. Some of the possible combinations of bases do not code for an amino acid.•3. One nucleotide triplet codes for more than one amino acid.•4. An amino acid can be encoded by more than one nucleotide triplet.RNApolymeraseTranscription-Initiationgene 1 gene 2gene 3DNARNA polymerase binds to the promoter region of DNA near the beginning of a gene, separating the double helix near the promoter.DNAFig. 12.3Transcription-ElongationRNA polymerase travels along the DNA template strand, catalyzing the addition of ribose nucleotides into an RNA molecule. The nucleotides in the RNA are complementary to the template strand of the DNA.RNADNA template strandFig. 12.3Transcription-TerminationAt the end of a gene, RNA polymerase encounters a sequence of DNA called a termination signal. RNA polymerase detaches from the DNA and releases the RNA molecule. Fig. 12.3RNAConclusion of transcriptionAfter termination, the DNA completely rewinds into a double helix. The RNA molecule is free to move from the nucleus to the cytoplasm for translation, and RNA polymerase may move to another gene and begin transcription once again, or it can even re-bind the same promoter and transcribe the same gene again.Fig. 12.3Fig. 12.4What is the order of steps in the transcription process?•1. Initiation, elongation, termination•2. Initiation, termination, elongation•3. Elongation, initiation, termination•4. Elongation, termination, initiationHow does initiation begin?•1. DNA polymerase finds a promoter region and binds, causing the DNA double helix to unwind.•2. RNA polymerase finds a promoter region and binds, causing the DNA double helix to unwind.•3. DNA synthase finds a promoter region and binds, causing the DNA double helix to unwind.•4. RNA synthase finds a promoter region and binds, causing the DNA double helix to unwind.If the mRNA transcript AUGCGCUGCAAU were to leave the nucleus and undergo translation at a ribosome, what would be the sequence of anticodons translating this nucleotide into protein?•1. TACGCGACGTTA•2. ATGCGCTGCAAT•3. AUGCGCUGCAAU •4. UACGCGACGUUATranslation is the RNA-directed synthesis of proteins.During translation, proteins are synthesized according to the genetic message of sequential
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