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Structure of RNA

Structure of RNA. Single strand of nucleotides bonded into a chain Each nucleotide contains Ribose , sugar Phosphate Nitrogen base: adenine, guanine, cytosine or uracil Adenine pairs with Uracil/ Cytosine pairs with Guanine. RNA Types.

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Structure of RNA

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  1. Structure of RNA Single strand of nucleotides bonded into a chain • Each nucleotide contains • Ribose, sugar • Phosphate • Nitrogen base: adenine, guanine, cytosine or uracil • Adenine pairs with Uracil/ Cytosinepairs with Guanine

  2. RNA Types • Messenger RNA- carries the code for making proteins • Ribosomal RNA- combine with a ribosome • Transfer RNA- brings the amino acid to the ribosome

  3. TRANSCRIPTION • When DNA gives RNA the code • RNA polymerase enzyme unzips DNA at Promoters • RNA nucleotides join the DNA complimentary bases • mRNA nucleotides bond and leave the nucleus

  4. http://www.pbs.org/wgbh/aso/tryit/dna/shockwave-nojs.html

  5. Transcription Cont. • Editing RNA sections called introns are spliced out leaving sections called exons • Exons splice together and leave the nucleus

  6.  Transcription Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA RNA Go to Section:

  7. TRANSLATION • Process of assembling proteins from the information encoded in RNA • mRNA leaves the nucleus and goes to the ribosome • the codon ( 3 bases in sequence on the mRNA) • tRNA, transfer RNA leaves the nucleus and picks up an amino acid • the anticodon is the compliment to the codon on mRNA

  8.  Translation Section 12-3 Nucleus Messenger RNA Messenger RNA is transcribed in the nucleus. mRNA Lysine Phenylalanine tRNA Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. Methionine Ribosome Start codon mRNA Go to Section:

  9.  Translation (continued) Section 12-3 The Polypeptide “Assembly Line” The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. Growing polypeptide chain Ribosome tRNA Lysine tRNA mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. mRNA Translation direction Ribosome Go to Section:

  10. START & STOP SIGNALS • To start the protein synthesis the codon AUG must be present • To stop the protein synthesis there’s a stop codon UAA, UGA, UUC

  11. Practice Use your book page 338

  12. Practice Answers

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