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The Genetic Code and Transcription

The Genetic Code and Transcription. Chapter 12 Honors Genetics Ms. Susan Chabot. Molecular Genetics - From DNA to Protein. Characteristics of the Genetic Code. mRNA is written in linear form using DNA as a template for synthesis.

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The Genetic Code and Transcription

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  1. The Genetic Code and Transcription Chapter 12 Honors Genetics Ms. Susan Chabot

  2. Molecular Genetics - From DNA to Protein

  3. Characteristics of the Genetic Code • mRNA is written in linear form using DNA as a template for synthesis. • Each “word” in the mRNA strand is composed of a 3-letter sequence called a CODON. • Each CODON specifies a SINGLE Amino Acid. • There is 1 start codon for initiation of protein synthesis and 3 stop codons for ending protein synthesis for a specific protein. • A given amino acid can have more than one codon sequence.

  4. The “Central Dogma” of Molecular Genetics

  5. There are Different RNAs with Distinct Functions

  6. Transcription is a Key Step in Gene Expression • Transcription makes an mRNA copy of DNA. • This mRNA copy is complementary to the gene sequence found on DNA. • DNA directs the synthesis of RNA in the nucleus.

  7. RNA Review RNA is a nucleic acid polymer that uses a slightly different sugar than DNA and the base uracil in place of thymine.

  8. RNA is Single-Stranded

  9. RNA polymerase acts here Transcription The enzyme RNA polymerase opens the DNA strands and synthesizes an RNA complement to only one of the DNA strands.

  10. A gene The most important step in the control of gene expression is WHEN to transcribe a gene.

  11. Eukaryotic Genes are Segmented Introns are removed from the primary transcript and exons are spliced together to make mRNA. In some genes, more than 90% of the pre-mRNA is destroyed, never to appear in the mRNA.

  12. The Genetic Language Uses 4 Letters Written Into 3-Letter Words

  13. What the Genetic Code Specifies: AMINO ACIDS Two examples

  14. What Translation Accomplishes The sequence of amino acids determines the structure, and therefore the function, of a protein. During translation, information present in the mRNA is read by the ribosome to synthesize a polypeptide.

  15. Many antibiotics block steps in translation within bacterial cells. Translation requires: ribosomes mRNA tRNA amino acids

  16. Ribosomes are Complicated Protein Synthesizing Machines

  17. Translation Is a Cyclic, Multistep Process

  18. A tobacco plant expressing the firefly luciferase gene. Basic Genetic Mechanisms are Universal The storage of genetic information in DNA, the use of an RNA intermediate that is read in three letter words, and the mechanism of protein synthesis are essentially the same in all organisms.

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