Protein synthesis with turning point

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  • Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.
  • Small nuclear ribonucleic acid (snRNA) is a class of small RNA molecules that are found within the nucleus of eukaryotic cells. They are transcribed by RNA polymerase II or RNA polymerase III and are involved in a variety of important processes such as RNA splicing (removal of introns from hnRNA ), regulation of transcription factors ( 7SK RNA ) or RNA polymerase II (B2 RNA), and maintaining the telomeres . They are always associated with specific proteins, and the complexes are referred to as small nuclear ribonucleoproteins (snRNP) or sometimes as snurps. These elements are rich in uridine content. A large group of snRNAs are known as small nucleolar RNAs (snoRNAs). These are small RNA molecules that play an essential role in RNA biogenesis and guide chemical modifications of ribosomal RNAs (rRNAs) and other RNA genes (tRNA and snRNAs). They are located in the nucleolus and the Cajal bodies of eukaryotic cells (the major sites of RNA synthesis).
  • Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein.
  • Protein synthesis with turning point

    1. 1. PROTEIN SYNTHESIS
    2. 2. DNA and Genes
    3. 3. DNA <ul><li>DNA contains genes , sequences of nucleotide bases </li></ul><ul><li>These Genes code for polypeptides (proteins) </li></ul><ul><li>Proteins are used to build cells and do much of the work inside cells </li></ul>
    4. 4. Genes & Proteins <ul><li>Proteins are made of amino acids linked together by peptide bonds </li></ul><ul><li>20 different amino acids exist </li></ul>
    5. 5. Amino Acid Structure
    6. 6. Polypeptides <ul><li>Amino acid chains are called polypeptides </li></ul>
    7. 7. DNA Begins the Process <ul><li>DNA is found inside the nucleus </li></ul><ul><li>Proteins , however, are made in the cytoplasm of cells by organelles called ribosomes </li></ul><ul><li>Ribosomes may be free in the cytosol or attached to the surface of rough ER </li></ul>
    8. 8. Starting with DNA <ul><li>DNA ‘s code must be copied and taken to the cytosol </li></ul><ul><li>In the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins) </li></ul><ul><li>This process is called PROTEIN SYNTHESIS </li></ul>
    9. 9. What macromolecule builds cells? <ul><li>Lipids </li></ul><ul><li>Proteins </li></ul><ul><li>Carbohydrates </li></ul><ul><li>Nucleic Acids </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    10. 10. What are proteins made of? <ul><li>DNA </li></ul><ul><li>RNA </li></ul><ul><li>Amino Acids </li></ul><ul><li>Nucleic Acids </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    11. 11. How many amino acids exist? <ul><li>10 </li></ul><ul><li>20 </li></ul><ul><li>30 </li></ul><ul><li>46 </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    12. 12. A chain of amino acids is a: <ul><li>Protein </li></ul><ul><li>Polypeptide </li></ul><ul><li>Both A & B </li></ul><ul><li>None of the Above </li></ul>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 20
    13. 13. Where are proteins made? <ul><li>Cytosol </li></ul><ul><li>Mitochondria </li></ul><ul><li>ER </li></ul><ul><li>Ribosomes </li></ul><ul><li>Nucleus </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    14. 14. RNA
    15. 15. Roles of RNA and DNA <ul><li>DNA is the MASTER PLAN </li></ul><ul><li>RNA is the BLUEPRINT of the Master Plan </li></ul>
    16. 16. RNA Differs from DNA <ul><li>RNA has a sugar ribose </li></ul><ul><li>DNA has a sugar deoxyribose </li></ul>
    17. 17. Other Differences <ul><li>RNA contains the base uracil (U ) </li></ul><ul><li>DNA has thymine (T) </li></ul><ul><li>RNA molecule is single-stranded </li></ul><ul><li>DNA is double-stranded </li></ul>DNA
    18. 18. Structure of RNA
    19. 19. Three Types of RNA <ul><li>Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes </li></ul><ul><li>Ribosomal RNA (rRNA) , along with protein, makes up the ribosomes </li></ul><ul><li>Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized </li></ul>.
    20. 20. Messenger RNA <ul><li>Long Straight chain of Nucleotides </li></ul><ul><li>Made in the Nucleus </li></ul><ul><li>Copies DNA & leaves through nuclear pores </li></ul><ul><li>Contains the Nitrogen Bases A, G, C, U ( no T ) </li></ul>
    21. 21. Messenger RNA (mRNA) <ul><li>Carries the information for a specific protein </li></ul><ul><li>Made up of 500 to 1000 nucleotides long </li></ul><ul><li>Sequence of 3 bases called codon </li></ul><ul><li>AUG – methionine or start codon </li></ul><ul><li>UAA, UAG, or UGA – stop codons </li></ul>
    22. 22. Ribosomal RNA (rRNA) <ul><li>rRNA is a single strand 100 to 3000 nucleotides long </li></ul><ul><li>Globular in shape </li></ul><ul><li>Made inside the nucleus of a cell </li></ul><ul><li>Associates with proteins to form ribosomes </li></ul><ul><li>Site of protein Synthesis </li></ul>
    23. 23. The Genetic Code <ul><li>A codon designates an amino acid </li></ul><ul><li>An amino acid may have more than one codon </li></ul><ul><li>There are 20 amino acids, but 64 possible codons </li></ul><ul><li>Some codons tell the ribosome to stop translating </li></ul>
    24. 24. The Genetic Code <ul><li>Use the code by reading from the center to the outside </li></ul><ul><li>Example: AUG codes for Methionine </li></ul>
    25. 25. Name the Amino Acids <ul><li>GGG? </li></ul><ul><li>UCA? </li></ul><ul><li>CAU? </li></ul><ul><li>GCA? </li></ul><ul><li>AAA? </li></ul>
    26. 26. Remember the Complementary Bases <ul><li>On DNA: </li></ul><ul><li>A-T </li></ul><ul><li>C-G </li></ul><ul><li>On RNA: </li></ul><ul><li>A-U </li></ul><ul><li>C-G </li></ul>
    27. 27. Transfer RNA (tRNA) <ul><li>Clover-leaf shape </li></ul><ul><li>Single stranded molecule with attachment site at one end for an amino acid </li></ul><ul><li>Opposite end has three nucleotide bases called the anticodon </li></ul>
    28. 28. Transfer RNA amino acid attachment site U A C anticodon
    29. 29. Codons and Anticodons <ul><li>The 3 bases of an anticodon are complementary to the 3 bases of a codon </li></ul><ul><li>Example: Codon ACU </li></ul><ul><li>Anticodon UGA </li></ul>UGA ACU
    30. 30. What sugar is found in RNA? <ul><li>Glucose </li></ul><ul><li>Sucrose </li></ul><ul><li>Ribose </li></ul><ul><li>Deoxyribose </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    31. 31. What are the 4 nitrogenous bases in RNA? <ul><li>A G C T </li></ul><ul><li>A G C U </li></ul><ul><li>A G T U </li></ul><ul><li>G C T U </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    32. 32. DNA has __ strand(s), RNA has ____ strand(s). <ul><li>2 , 2 </li></ul><ul><li>2 , 3 </li></ul><ul><li>1 , 2 </li></ul><ul><li>2 , 1 </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    33. 33. The type of RNA that transfers amino acids to ribosomes. <ul><li>snRNA </li></ul><ul><li>mRNA </li></ul><ul><li>rRNA </li></ul><ul><li>tRNA </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    34. 34. The tyoe of RNA that makes up the ribosome. <ul><li>snRNA </li></ul><ul><li>mRNA </li></ul><ul><li>rRNA </li></ul><ul><li>tRNA </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    35. 35. The type of RNA that copies DNA’s code. <ul><li>snRNA </li></ul><ul><li>mRNA </li></ul><ul><li>rRNA </li></ul><ul><li>tRNA </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    36. 36. What is a sequence of three nitrogen bases called? <ul><li>DNA </li></ul><ul><li>RNA </li></ul><ul><li>Codon </li></ul><ul><li>Antiparrallel </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    37. 37. What mRNA would be made from this DNA sequence: ATCGGCTAA <ul><li>TAGCCGATT </li></ul><ul><li>ATCGGCTAA </li></ul><ul><li>UAGCCGAUU </li></ul><ul><li>TUGCCGUTT </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    38. 38. Transcription and Translation
    39. 39. Pathway to Making a Protein <ul><li>DNA </li></ul><ul><li>mRNA </li></ul><ul><li>tRNA (ribosomes) </li></ul><ul><li>Protein </li></ul>
    40. 40. Protein Synthesis <ul><li>The production or synthesis of polypeptide chains (proteins) </li></ul><ul><li>Two phases: Transcription & Translation </li></ul><ul><li>mRNA must be processed before it leaves the nucleus of eukaryotic cells </li></ul>
    41. 41. DNA  RNA  Protein Eukaryotic Cell Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein
    42. 42. Transcription <ul><li>The process of copying the sequence of one strand of DNA, the template strand </li></ul><ul><li>mRNA copies the template strand </li></ul><ul><li>Requires the enzyme RNA Polymerase </li></ul>
    43. 43. Template Strand
    44. 44. Question: <ul><li>What would be the complementary RNA strand for the following DNA sequence? </li></ul><ul><li>DNA 5’- GCGTATG -3’ </li></ul>
    45. 45. Answer: <ul><li>DNA 5’-GCGTATG-3’ </li></ul><ul><li>RNA 3’-CGCAUAC-5’ </li></ul>
    46. 46. Transcription <ul><li>During transcription, RNA polymerase binds to DNA and separates the DNA strands </li></ul><ul><li>RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA </li></ul>
    47. 47. Transcription <ul><li>Promoters are regions on DNA that show where RNA Polymerase must bind to begin the Transcription of RNA </li></ul><ul><li>Called the TATA box </li></ul><ul><li>Specific base sequences act as signals to stop </li></ul><ul><li>Called the termination signal </li></ul>
    48. 48. RNA Polymerase
    49. 49. mRNA Processing <ul><li>After the DNA is transcribed into RNA, editing must be done to the nucleotide chain to make the RNA functional </li></ul><ul><li>Introns , non-functional segments of DNA are snipped out of the chain </li></ul>
    50. 50. mRNA Editing <ul><li>Exons , segments of DNA that code for proteins, are then rejoined by the enzyme ligase </li></ul><ul><li>A guanine triphosphate cap is added to the 5” end of the newly copied mRNA </li></ul><ul><li>A poly A tail is added to the 3’ end of the RNA </li></ul><ul><li>The newly processed mRNA can then leave the nucleus </li></ul>
    51. 51. CAP Tail New Transcript Result of Transcription
    52. 52. mRNA Transcript <ul><li>mRNA leaves the nucleus through its pores and goes to the ribosomes </li></ul>
    53. 53. Translation <ul><li>Translation is the process of decoding the mRNA into a polypeptide chain </li></ul><ul><li>Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins </li></ul>
    54. 54. Transcription Translation
    55. 55. Ribosomes <ul><li>Made of a large and small subunit </li></ul><ul><li>Composed of rRNA (40%) and proteins (60%) </li></ul><ul><li>Have two sites for tRNA attachment --- P and A </li></ul>
    56. 56. Step 1- Initiation <ul><li>mRNA transcript start codon AUG attaches to the small ribosomal subunit </li></ul><ul><li>Small subunit attaches to large ribosomal subunit </li></ul>mRNA transcript
    57. 57. Ribosomes P Site A Site Large subunit Small subunit mRNA A U G C U A C U U C G
    58. 58. Step 2 - Elongation <ul><li>As ribosome moves , two tRNA with their amino acids move into site A and P of the ribosome </li></ul><ul><li>Peptide bonds join the amino acids </li></ul>
    59. 59. Initiation mRNA A U G C U A C U U C G A anticodon hydrogen bonds codon 2-tRNA G aa2 A U 1-tRNA U A C aa1
    60. 60. mRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A anticodon hydrogen bonds codon peptide bond Elongation 3-tRNA G A A aa3
    61. 61. mRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A peptide bond Ribosomes move over one codon (leaves) 3-tRNA G A A aa3
    62. 62. mRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 A C U 4-tRNA G C U aa4
    63. 63. mRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 A C U (leaves) Ribosomes move over one codon 4-tRNA G C U aa4
    64. 64. mRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U U G A 5-tRNA aa5
    65. 65. mRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U Ribosomes move over one codon U G A 5-tRNA aa5
    66. 66. mRNA A C A U G U aa1 aa2 U primary structure of a protein aa3 200-tRNA aa4 U A G aa5 C U aa200 aa199 terminator or stop codon Termination
    67. 67. End Product –The Protein! <ul><li>The end products of protein synthesis is a primary structure of a protein </li></ul><ul><li>A sequence of amino acid bonded together by peptide bonds </li></ul>aa1 aa2 aa3 aa4 aa5 aa200 aa199
    68. 68. Messenger RNA (mRNA) methionine glycine serine isoleucine glycine alanine stop codon protein A U G G G C U C C A U C G G C G C A U A A mRNA start codon Primary structure of a protein aa1 aa2 aa3 aa4 aa5 aa6 peptide bonds codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 codon 1

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