section 5, chapter 4

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protein synthesis

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  • 1.Section 5, Chapter 4Transcription & Translation

2. There are several kinds of RNA Messenger RNA (mRNA): Conveys genetic information from DNA to the ribosomesTransfer RNA (tRNA): Transfers amino acids to the ribosomes during translation.Ribosomal RNA (rRNA): Provides structure and enzyme activity for ribosomes4 3. Messenger RNA (mRNA): Delivers genetic information from the DNA inside the nucleus to the cytoplasm mRNA is formed beside a strand of DNA RNA nucleotides are complementary to DNA nucleotides with one exception no thymine in RNA; replaced with uracil) mRNADNASPAUTAGCCGGCPDirection of reading codeS SPPS SPPS SPPS SP SCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.P 4. 5.mRNA undergoes further processing & leaves the nucleus 5. A Codon is the 3 letter nucleotide sequence of mRNA that encodes for 1 amino acid. AUG is the first codon in protein synthesis, so its its called the start codon 6. Protein Synthesis The codon sequence of mRNA determines the amino acid sequence of a protein.Figure 4.23 7. The start codon marks the site at which translation into protein sequence begins, and the stop codon marks the site at which translation ends.amino acid 8. tRNA Clover-leaf shape RNA with 2 important regionsAmino acid binding siteAnticodon 9. Ribosomes Small particle of protein & ribosomal RNA (rRNA) Ribosomes have 2 subunits Large subunit holds tRNA & amino acids Small subunit binds to mRNASmall subunit has 2 binding sites for adjacent mRNA codons Ribosomes link amino acids by peptide bonds 10. Ribosomes Peptide bond forminglarge subunit anticodonssmall subunit Binding sites with codons 11. 1. mRNA binds to the small subunit of a Ribosome.2. The ribosome reads the mRNA sequence 3. tRNA brings amino acids to the ribosomes, aligning their anticodons with mRNA codons4. The Ribosome links the amino acids together 5. Polypeptide chain lengthens 12. Anchors polypeptide. 13. tRNA released 14. Figure 4.23 overview of protein synthesisTRANSCRIPTION 15. Once translation is complete chaperone proteins fold the protein into its configurationpost-translational modification enzymes may further modify proteins after translation phosphorylation adding a phosphate to the protein glycosylation adding a sugar to the proteinEnd of Chapter 4