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PROTEIN SYNTHESIS

PROTEIN SYNTHESIS. Biology 102 SB2b. Explain the role of DNA in storing and transmitting cellular information. GENERAL OVERVIEW. What determines the structure and function of an organism?. The way you look and act is determined by different types of PROTEINS .

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PROTEIN SYNTHESIS

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  1. PROTEIN SYNTHESIS Biology 102 SB2b. Explain the role of DNA in storing and transmitting cellular information.

  2. GENERAL OVERVIEW

  3. What determines the structure and function of an organism? • The way you look and act is determined by different types of PROTEINS. • Your types of proteins are determined by the number and arrangement of your AMINO ACID SEQUENCES. • Your amino acid sequences are determined by the arrangement of your NITROGEN BASES (A, T, C, G) • Nitrogen base arrangements are determined by your DNA code that you inherited from your parents. Protein consisting of amino acids (“beads”) Each amino acid “bead” consist of 3 nitrogen bases

  4. How is a DNA code read to make a protein? • One codon codes for one amino acid. • DNA codon has to be transcribed (copied) into mRNA in order to find the amino acid. • When DNA is copied by RNA, remember, it uses a U instead of T • The DNA code for an amino acid is arranged in a set of 3 letters called a codon.

  5. PRACTICE… If the DNA strand is: ATT GAA CAC GTC What is the matching mRNA strand? UAA CUU GUG CAG

  6. If you know the DNA strand, you can figure out the mRNA strand, then figure out the amino acid sequence. • Figuring out the amino acid sequence can help determine what type of protein is being formed. • You have to use an mRNA codon chart to figure out the amino acid codes.

  7. Use your codon chart to answer the following questions… • What is the amino acid that the codon UCG calls for? • serine • What are 2 mRNA codons that could code for lysine? • AAA or AAG

  8. What if you were given… DNA strand TAC CAA GTG AAT TGC AUG GUU CAC UUA ACG mRNA strand meth valine histidine leucine threonine Amino Acid strand This is the partial “ingredients” (amino acid sequence code) for the protein hemoglobin- the part of your blood that carries oxygen. In reality this protein consists of hundreds of amino acids not just 5.

  9. The process we just “overviewed” is called PROTEIN SYNTHESIS. It occurs in TWO steps: Step 1- TRANSCRIPTION

  10. What is transcription • Process by which a segment of DNA is copied by mRNA

  11. Where does transcription occur? • Occurs in the nucleus

  12. What are the steps of transcription? 1. RNA polymerase enzyme attaches to DNA • RNA polymerase unwinds DNA helix • RNA nucleotides bind to DNA strand, elongating as it goes. • DNA binds back together as mRNA is created. • RNA polymerase reaches a stop codon. • mRNA is released and is sent to the cytoplasm. http://www.hhmi.org/biointeractive/dna-transcription-basic-detail

  13. PROTEIN SYNTHESIS:Step 2: Translation

  14. What is translation? • Process by which newly formed mRNA is read, amino acids are linked, and protein formation begins.

  15. Where does translation occur? • Occurs in the cytoplasm or Rough ER on the ribosomes.

  16. What are the steps of translation? • mRNA binds to ribosome in the cytoplasm • First tRNA binds to mRNA start codon (AUG). • tRNA’s pick up the correct amino acid and carry them to the mRNA strand. • tRNA anticodons match mRNA codons, amino acids peptide bond together. tRNA is released. • Process continues as mRNA moves down ribosome until stop codon is reached. • Polypeptide (protein chain) is finished and released. http://www.hhmi.org/biointeractive/translation-basic-detail

  17. http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a1.htmlhttp://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a1.html

  18. Quiz- RNA & Protein Synthesis • Figure out the mRNA code and Amino Acid sequence for the DNA strand on the back of this paper. • Which process involves mRNA making a copy of DNA? • Transcription • photosynthesis • Translation • Which process involves mRNA codes being decoded and amino acids being joined to make a protein? • Transcription • Respiration • translation • Where does transcription occur? • In the nucleus • In the cytoplasm • On a ribosome 5. Which statement best describes protein production? • Only animals produce proteins • Proteins are produced in the livers of animals • DNA in cells direct the production of the proteins • Proteins are produced in the nucleus of cells

  19. How many amino acids does this strand of DNA code for? (draw lines after each 3rd letter) DNA- GCGCTAAAATGC mRNA- ________________ Amino acids _______________________

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