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DNA, RNA and PROTEIN SYNTHESIS sections 12.3 and 12.4

DNA, RNA and PROTEIN SYNTHESIS sections 12.3 and 12.4. What is protein synthesis? What is the relationship between DNA and RNA and protein synthesis? What functions do proteins perform in living things?. Ribonucleic Acid (RNA)…. organic compound (contains C+H)

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DNA, RNA and PROTEIN SYNTHESIS sections 12.3 and 12.4

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  1. DNA, RNA and PROTEIN SYNTHESIS sections 12.3 and 12.4

  2. What is protein synthesis? What is the relationship between DNA and RNA and protein synthesis? What functions do proteins perform in living things?

  3. Ribonucleic Acid (RNA)… • organic compound (contains C+H) • polymer - composed of monomers called nucleotides • composed of a SINGLE STRAND of nucleotides • carries out protein synthesis (the making of proteins) 3 types of RNA…. • messenger RNA (mRNA) • transfer RNA (tRNA) • ribosomal RNA (rRNA)

  4. Ribonucleic Acid (RNA) Ribosomal RNA Transfer RNA Messenger RNA RNA takes on 3 different shapes. All are used in protein synthesis.

  5. RNA nucleotide has 3 parts… • a ribose sugar covalently • a phosphate group bonded • a nitrogen base of which there are 4 kinds - A, U (uracil), C,G In RNA – uracil takes the place of thymine In RNA…. A pairs with U C pairs with G

  6. RNA nucleotide structure: Nitrogen Base (A, U, C, G) Phosphate Group Ribose Sugar

  7. RNA nucleotide structure: PHOSPHATE GROUP NITROGEN BASE (A, U, C, G) RIBOSE SUGAR

  8. RNA differs from DNA: RNA has… • 1. ribose sugar (instead of deoxyribose) • 2. a single strand of nucleotides (instead of a double helix) • 3. the N base uracil (instead of thymine)

  9. Transcription…the process of making RNA from DNA template 2 steps: • an enzyme separates N-bases of DNA • a complementary RNA chain is made the RNA breaks away and the DNA reforms 3 products: • mRNA, tRNA, rRNA

  10. Messenger RNA (mRNA) • linear form • carries the message from nucleus to a ribosome (site of protein synthesis)

  11. mRNA 3 N bases = codon each codon codes for a specific amino acid

  12. Transfer RNA (tRNA) • “t” shaped • transfers amino acids to the site of protein synthesis (ribosome)

  13. tRNA 3 N bases = anticodon anti-codons align with codons on mRNA

  14. Ribosomal RNA (rRNA) • globular form • makes up ribosomes • this is where protein synthesis occurs

  15. rRNA

  16. Importance of Protein… Your body uses the proteins you eat (the amino acids you ingest) to make specialized proteins that have specific jobs!!! • LIKE…. Insulin, Actin, Hemoglobin, Collagen and Elastin, Pepsinand Trypsin and other enzymes, Antibodies and many, many more….. You need protein !!!!

  17. Proteins are the MOST VERSATILE cellular components

  18. Translation….the making of proteins from the information encoded in DNA this process makes ALL types of proteins amino acids  polypeptide chain  protein occurs at a ribosome (site of protein synthesis) In this process all 3 types of RNA are used . . . . . • mRNA carries the instructions for making a protein • tRNA transfers amino acids (materials) to the ribosome • rRNA assists in the binding of mRNA and tRNA

  19. Steps in Translation • mRNA leaves nucleus and goes to ribosome • tRNA carries amino acids to ribosome • codons (on mRNA) + anticodons (on tRNA) align and bring amino acids into their correct sequence • When100 amino acids are assembled = polypeptide chain • polypeptide chains will detach and wrap with other chains to form a protein * process only begins with a start (AUG) codon * process will only stop with a stop codon (UGA, UAG,…)

  20. A look at translation…

  21. Let’s look at it again

  22. RNA Editing – RNA molecules require a bit of editing before they are ready to go into action • Introns – a non-coding sequence of RNA (does not code for a protein) “a deleted sequence of RNA” • Exons – an expressed sequence of RNA

  23. Introns – Deleted sequence of RNA • Exons – Expressed sequence of RNA

  24. The Genetic Code amino acids polypeptide chains proteins the genetic code is read 3 letters at a time example - AUG, CAA, UCG, ACC, GAC each sequence of 3 letters “codes” for a specific amino acid as amino acids are put into a specific order they produce a specific type of protein

  25. MUTATION = a change in the DNA (nucleotide) sequence • mutations may be helpful, harmful or have no affect at all • mutagens – substances which cause mutations • body cell mutation versus sex cell mutation Mutations are of 2 kinds: • GENE MUTATIONS • CHROMOSOME MUTATIONS

  26. GENE MUTATIONS • a mutation in a single gene • it may involve 1 or several nucleotides GENE = REGION/SEGMENT OF DNA THAT CODES FOR A PARTICULAR TRAIT

  27. POINT MUTATIONS mutations that affect 1 nucleotide • substitution, insertion (addition) or deletion original sequence ACC,UUA,GAC… substitution ACG, UUA, GAC… insertion ACC, CUU, AGA, C… deletion _CCU, UAG, AC…

  28. FRAMESHIFT MUTATIONS • a point mutation caused by the INSERTION or DELETION of a single nucleotide • results in a shift of the “frame of reference” in the reading of the N base sequence original sequence ACC,UUA,GAC… insertion ACC, CUU, AGA, C… deletion _CCU, UAG, AC…

  29. CHROMOSOME MUTATIONS – involve segments or whole chromosomes • types of chromosome mutations include: deletion, inversion, translocation, nondisjunction • we have already studied these

  30. Gene Regulation • the ability to control (regulate) which genes are transcribed (“turned on”) • different genes may be transcribed (“turned on”) at different times during an organism’s life • a gene is expressed or “turned on” only if transcription occurs OPERON – segment of DNA that contains the genes for the proteins to be transcribed OPERATOR – segment of DNA that acts as an on/off switch for transcription

  31. Special Genes Hox Genes (or homeobox genes) • genes that determine the basic body plan of an organism • control what body part will develop in a given location • control DIFFERENTIATION - process through which the cells become specialized in structure and function • a mutation in one of these genes can completely change the organs that develop in specific parts of the body

  32. Special Genes Oncogenes – genes that promote uncontrolled cell division which may lead to cancer – genetic mutations may result to the activation of oncogenes Tumor Suppressor Genes – genes that act to prevent DNA damage and inhibit uncontrolled cell division which may prohibit cancer development ONCOGENES AND TUMOR SUPPRESSOR GENES ARE THOUGHT TO BE IN A PERPETUAL TUG-OF WAR Remember, a gene is not “turned on” until it goes through transcription

  33. To summarize: • Transcription DNA  RNA • Translation RNA  Protein

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