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From DNA to Protein

From DNA to Protein. Chapter 14. Ricin and your Ribosomes. DNA and RNA. RNAs have various functions. Some serve as disposable copies of DNA’s genetic message; others are catalytic. DNA has one function: It permanently stores a cell’s genetic information, which is passed to offspring.

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From DNA to Protein

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  1. From DNA to Protein Chapter 14

  2. Ricin and your Ribosomes

  3. DNA and RNA RNAs have various functions. Some serve as disposable copies of DNA’s genetic message; others are catalytic. DNA has one function: It permanently stores a cell’s genetic information, which is passed to offspring.

  4. DNA template Transcription mRNA Translation Gly stop protein Glu Amino acid Amino acid Amino acid

  5. RNA in Protein Synthesis2 Different Kinds of RNA: • Messenger RNA (mRNA) Contains information transcribed from DNA • Transfer RNA (tRNA) Delivers amino acids to ribosomes

  6. Gene Expression • Gene expression A multistep process in which genetic information is converted into a structural or functional part of a cell or body

  7. Transcription: DNA to RNA • RNA polymerase assembles RNA by linking RNA nucleotides into a chain

  8. Transcription: DNA to RNA DNA template Transcription mRNA

  9. Base-Pairing in DNA Synthesis and Transcription

  10. Fig. 14-5a, p. 218

  11. Post-Transcriptional Modifications exon intron exon intron exon gene DNA transcription into RNA poly-A tail cap Pre- 3’ mRNA 5’ snipped out snipped out mRNA Fig. 14-7, p. 220

  12. mRNA – The Messenger • Codon-A sequence of 3 mRNA nucleotides that codes for a specific amino acid • The order of codons in mRNA determines the order of amino acids in a polypeptide chain

  13. Genetic Information • From DNA to mRNA to amino acid sequence codon

  14. Translation 2 subunits Ribosomes made of rRNA & proteins

  15. Codons of the Genetic Code

  16. Mutated Genes & Their Protein Products • Mutations • Small-scale changes in the nucleotide sequence of a cell’s DNA that alter the genetic code

  17. Common Mutations • Base-pair-substitution • Deletion or insertion

  18. Normal Hemoglobin chain THREONINE PROLINE GLUTAMATE GLUTAMATE LYSINE b. Base pair substitution THREONINE PROLINE VALINE GLUTAMATE LYSINE c. Frame shift THREONINE PROLINE GLYCINE ARGININE Fig. 14-13, p. 224

  19. What Causes Mutations? • Spontaneous mutations • Uncorrected errors in DNA replication • Harmful environmental agents a. UV radiation b. chemicals

  20. Inherited Mutations • Mutations in somatic cells of sexually reproducing species are not inherited • Mutations in a gamete may be inherited, with evolutionary consequences

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