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PROTEIN SYNTHESIS

PROTEIN SYNTHESIS. PROTEIN SYNTHESIS. Process of using DNA to make protein Function of protein in body Enzymes Immunity Communication between cells structural Characteristics (skin color, eye color, etc…). Structure of DNA. Double helix Nucleotides Dexyribose (5 carbon sugar)

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PROTEIN SYNTHESIS

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  1. PROTEIN SYNTHESIS

  2. PROTEIN SYNTHESIS • Process of using DNA to make protein • Function of protein in body • Enzymes • Immunity • Communication between cells • structural • Characteristics (skin color, eye color, etc…)

  3. Structure of DNA • Double helix • Nucleotides • Dexyribose (5 carbon sugar) • Phosphate • Nitrogen base (A,T,C,G)

  4. DNA

  5. DNA

  6. BASES

  7. HELPERS • RNA - ribonucleic acid • Single strand of nucleotides • Can act as a messenger between DNA and ribosomes Ribosomes - where protein is “constructed” 3 types of RNA mRNA tRNA rRNA

  8. 3 Stages of Protein synthesis • 1. Transcription - “write recipe down” • 2. Translation - “put recipe together” • 3. Elongation - “glue” amino acids together to form protein

  9. SUMMARY

  10. Transcription • Occurs in nucleus of cell • Process by which molecule of DNA is copied into complementary strand of mRNA

  11. Steps of Transcription 1. DNA unwinds and unzips (helicase) (only in area of the recipe) creating 2 strands. An active strand and “dummy”strand 2. Active strand is the one to be used to make the protein (the template) 3. Special sequence of DNA is recognized by RNA polymerase as the “start signal” (promoter)

  12. Steps of transcription cont… 4. RNA polymerase matches up complementary bases between DNA and RNA (A-U, C-G), using DNA as a template 5. RNA polymerase moves along the area of the DNA with the recipe, matching up complementary bases (elongation phase) 6. when it hits the “stop codon” mRNA drops off DNA.(termination phase) 7. At this point mRNA has “copied” the recipe for the protein. • DNA winds back up and mRNA gets modified before leaving the nucleus

  13. TRANSCRIPTION

  14. mRNA modification • While still in the nucleus, mRNA gets modified. • mRNA consists of exons and introns • An enzyme comes along and splices out the introns (pieces of DNA) that is not part of the recipe needed for the protein. • Exons are then spliced together to create the “real recipe” for the protein your body needs • Exons are capped and tailed for protection and then leave the nucleus via nuclear pores.

  15. EXONS AND INTRONS

  16. WHY COPY DNA???? • DNA is too large to leave the nucleus, so it needs a messenger to bring genetic information to the ribosome in the cytoplasm. • This messenger is the mRNA

  17. TRANSLATION • Process of decoding mRNA into protein • Code being translated from language of nucleic acids into polypeptide

  18. STEPS OF TRANSLATION • 1. mRNA attaches onto a ribosome and the first codon “start” is read by the ribosome. This signals ribosome to start translating the recipe (initation phase) • 2. The ribosome reads each codon of mRNA and signals tRNA (complementary nitrogen bases which are carrying a specific amino acid. (Also called an anticodon) • 3. Complementary tRNA matches up with mRNA codon, and brings the amino acid along with it.

  19. IN THE CYTOPLASM

  20. Translation cont…. • 4. The ribosome moves along the mRNA reading it and signaling tRNA to bring amino acids to the ribosome. • 5. The amino acids are bonded together, the previous one with the next one in line. (elongation) • 6. This continues until the ribosome hits the stop codon. (terminiation) • 7. When hits stop codon, mRNa breaks off and returns to the nucleus (disassembles) • 8. All that is left is a string of amino acids in a specific order. This specific order is what determines the name and type of protein that was just made.

  21. TRANSLATION ON RIBOSOME

  22. TRANSLATION

  23. Translation

  24. ELONGATION • The string of amino acids is bonded together (during the process of translation) to create the protein that your body needs.

  25. http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302

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