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Proteins are made by decoding the Information in DNA

Proteins are made by decoding the Information in DNA. Proteins are not built directly from DNA. A molecule called RNA – ribonucleic acid is used to decode the instructions in DNA,. RNA Structure. Like DNA, RNA is a nucleic acid. RNA is a nucleic acid made up of repeating nucleotides.

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Proteins are made by decoding the Information in DNA

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  1. Proteins are made by decoding the Information in DNA • Proteins are not built directly from DNA

  2. A molecule called RNA – ribonucleic acid is used to decode the instructions in DNA,

  3. RNA Structure • Like DNA, RNA is a nucleic acid. • RNA is a nucleic acid made up of repeating nucleotides

  4. RNA differs from DNAin three different ways. • The sugar in RNA is ribose • RNA is single- stranded • RNA contains the base uracil instead of thymine. • Like thymine, uracil can form bonds with adenine

  5. Transcription • The instructions for making a protein are transferred from a gene (DNA) to RNA • Transcription = DNA → RNA

  6. Segment of DNA unwinds • DNA unzips • RNA is produced one nucleotide at a time by matching base pairs with the nucleotides in DNA.

  7. After the synthesis is complete, the RNA separates from the DNA and the DNA recoils into its helix. • The RNA strand leaves the nucleus and goes into cytoplasm

  8. In what part of the cell does transcription take place? • RNA makes proteins. • Where are proteins made in the cell?

  9. Forms of RNA

  10. Messenger RNA - mRNA • mRNA carries the information to the cytoplasm where the ribosomes can make it into protein. • "Blueprint" for protein synthesis that is transcribed from one strand of the DNA (gene) and which is translated at the ribosome into a polypeptide sequence.

  11. Ribosomes take RNA coded information and "translate" that information into chains of amino acids called pollypeptides • A protein is made up of one or more polypeptide chains.

  12. Ribosomal rRNA • a structural component of the ribosome.

  13. tRNA • molecule that converts nucleic acid sequence to protein sequence

  14. tRNA - transfer RNA • It acts as an adaptor to carry the amino acid elements of a protein to the appropriate place as coded for by the mRNA. • Small, single-stranded RNA molecules that bind to amino acids and deliver them to the proper codon on messenger RNA.

  15. Messenger RNA (mRNA) is the blueprint for construction of a protein. • Ribosomal RNA (rRNA) is the construction site where the protein is made. • Transfer RNA (tRNA) is the truck delivering the proper amino acid to the site at the right time.

  16. Translation • The ribosome reads the mRNA sequence and translates it (or decodes it) into an amino acid sequence in a polypeptide.

  17. Polypeptidesare chains of amino acids. • Proteins are made up of one or more polypeptide molecules. • So….the building block of proteins are ___________________.

  18. There are 20 essential amino acids that make up proteins. • The instructions in DNA specify the order in which the amino acids are put together.

  19. RNA – contains 4 different nucleotides. • (Language – 4 letters) How can a code with only 4 letters carry instructions for 20 amino acids?

  20. # of letters # of words 1 4 2 16 3 64 The genetic code could signify 64 different words

  21. The group of 3 nucleotides in mRNA that specifies an amino acid is known as a codon. • Think of codons as the words of the genetic message.

  22. Example: The following sequence of nucleotides in mRNA • AAACACGGU Would be read as 3 codons AAA- CAC-GGU And each codon represents a different _____.

  23. First Second Third U C A G U U UUUPhenylalanine UCUSerine UAUTyrosine UGUCysteine C UUCPhenylalanine UCCSerine UACTyrosine UGCCysteine A UUALeucine UCASerine UAASTOP UGASTOP G UUGLeucine UCGSerine UAGSTOP UGGTryptophan C U CUULeucine CCUProline CAUHistidine CGUArginine C CUCLeucine CCCProline CACHistidine CGCArginine A CUALeucine CCAProline CAAGlutamine CGAArginine G CUGLeucine CCGProline CAGGlutamine CGGArginine A U AUUIsoleucine ACUThreonine AAUAsparagine AGUSerine C AUCIsoleucine ACCThreonine AACAsparagine AGCSerine A AUAIsoleucine> ACAThreonine AAALysine AGAArginine G AUGMethionine ACGThreonine AAGLysine AGGArginine G U GUUValine GCUAlanine GAUAspartic acid GGUGlycine C GUCValine ValineAlanine GACAspartic acid GGCGlycine A GUAValine GCAAlanine GAAGlutamic acid GGAGlycine G GUGValine GCGAlanine GAGGlutamic acid GGGGlycine

  24. Page figure Shows all 64 possible codons of the genetic code. Notice: More than one codon can specify the same amino acid.

  25. How do tRNAs recognize to which codon to bring an amino acid? The tRNA has an anticodon that is complementary to the codon on the mRNA. Each tRNA only binds the appropriate amino acid for its anticodon

  26. amino acids are carried by the molecules of tRNA. • The ribosomes “read” the codons in mRNA allowing tRNA molecules to bring the proper amino acid. (the anti-codon on tRNA bonds to the proper codon on mRNA)

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