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Protein Synthesis

Protein Synthesis. RNA carries DNA’s instructions. Information flows in one direction from to to. replication. transcription. translation. Protein Synthesis involves 2 processes:. RNA is a link between DNA and proteins. 3.5.1 – Compare the structure of RNA and DNA.

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Protein Synthesis

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  1. Protein Synthesis

  2. RNA carries DNA’s instructions. • Information flows in one direction from to to .

  3. replication transcription translation Protein Synthesis involves 2 processes: RNA is a link between DNA and proteins.

  4. 3.5.1 – Compare the structure of RNA and DNA. RNA differs from DNA in three major ways. • Sugar: • RNA has a • DNA has a • Bases: • RNA has instead of • Number of strands: • RNA is • DNA is

  5. Three types of RNA • messenger RNA (mRNA) – • mRNA nucleotides are read in groups of three called • each codon codes for a

  6. mRNA

  7. Three types of RNA • transfer RNA (tRNA) – • Each tRNA carries a specific type of amino acid • Each tRNA can (sequence of three bases that associates with the codon by base pairing)

  8. tRNA If the mRNA codon was AUG, what would the anticodon be?

  9. Three types of RNA • ribosomal RNA (rRNA) –

  10. Overview of Protein Synthesis • During transcription, one DNA strand, (template strand), provides a template for making an mRNA molecule. • Complementary mRNA molecule is made using base-pairing rules, except uracil pairs with adenine. If the DNA template was ATG, which mRNA bases would pair with it?

  11. Overview of Protein Synthesis • During translation, blocks of three nucleotides (codons) are decoded into a sequence of amino acids.

  12. RNA polymerase start site nucleotides 3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase • Transcription • Takes place in the • Copies • Transcription is catalyzed by

  13. DNA RNA polymerase moves along the DNA 3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase • Nucleotides pair with one strand of the DNA. • RNA polymerase • The DNA helix winds again as the gene is transcribed.

  14. 3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase • mRNA is a complementary copy of DNA – travels out of nucleus to Ex. DNA A T C C G G A A T C G G T A AA T T mRNA

  15. RNA 3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase • The mRNA strand detaches from the DNA once the gene is transcribed

  16. 3.5.4 – Explain the process of translation leading to polypeptide formation • Translation • In the process of translation, . • Transfer RNA (tRNA) transfers amino acids from the cytoplasm’s pool to a ribosome. • The ribosome .

  17. codon for leucine (Leu) codon for methionine (Met) 3.5.3 – Describe the genetic code in terms of codons composed of triplets of bases. • Amino acids are coded by • Translation • A is a sequence of three nucleotides on mRNA that codes for a particular amino acid

  18. 3.5.4 – Explain the process of translation leading to polypeptide formation • Amino acids are put in a specific order to – the order of the amino acids is determined by the • Regardless of the organism,

  19. 3.5.4 – Explain the process of translation leading to polypeptide formation • Ribosomes consist of two subunits. • The large subunit has . • The small subunit

  20. 3.5.4 – Explain the process of translation leading to polypeptide formation • How does the ribosome “read” and translate the mRNA? • Step1: • A special initiator tRNA attaches to the • The large subunit of the ribosome closes over the tRNA • In all organisms, protein synthesis begins with the codon (codes for )

  21. Step2: • The polypeptide chain grows as new tRNA molecules move into position by complementary base pairing of their anticodon with the next codon on the mRNA

  22. Ribosome links amino acids together by • Translation continues until ribosome reaches a • Codons that do not code for an amino acid • Indicates that

  23. The genetic code matches each codon to its amino acid • The genetic code is (redundant) • More than one codon codes for CODONAMINO ACID AGU AGC GGU

  24. 3.5.5 – Discuss the relationship between one gene and one polypeptide • The genetic code – the sequence of nucleotides in DNA – is ultimately translated into the sequence of amino acids in proteins – gene expression • In general, (can be structural or enzymatic) – one-gene, one-protein hypothesis • Exceptions…are all protein made of one polypeptide???

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