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Protein Synthesis

Protein Synthesis. SBI 4U November 8 th , 2012. Agenda. Present analogies Take up homework Lesson. Homework: Pg 223, 1, 2, 4, 5. 2. . Homework: Pg 223, 1, 2, 4, 5.

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Protein Synthesis

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  1. Protein Synthesis SBI 4U November 8th, 2012

  2. Agenda Present analogies Take up homework Lesson

  3. Homework: Pg 223, 1, 2, 4, 5 2.

  4. Homework: Pg 223, 1, 2, 4, 5 4. A replication fork is the region where the enzymes replicating a DNA molecule are bound to the untwisted, single-stranded DNA, whereas a replication bubble is formed when two replication forks are in close proximity to each other, resulting a bubble of single-stranded DNA between them

  5. Homework: Pg 223, 1, 2, 4, 5 5. It is necessary for eukaryotic DNA to have multiple replication origin sites due to its size. It would take too long for DNA replication to occur if replication started at one end of a DNA molecule and proceeded to the other end. Multiple replication origin sites allow for efficiency in replication

  6. Introduction Genes: direct the production of proteins Proteins: determine the phenotypical characteristics of organisms, drive cellular processes and manifest genetic disorders How do genes code for proteins?

  7. The Triplet Hypothesis Crick took up the challenge of deciphering the genetic code Code must be made of “words” or codons – minimum 3 nucleotides each 3 nucleotides each  more than enough for the 20 different amino acids CUU or CUC code for Leucine

  8. The Triplet Hypothesis, contd.. Genetic code codons made up nucleotide triplets  triplet hypothesis

  9. The Transfer of Genetic Information Before discovering the structure of DNA  Watson & Crick had started to devise a theory that genetic information is somehow transmitted from DNA to RNA and then to proteins How did they know this? Because DNA never left the nucleus

  10. The Transfer of Genetic Information Crick’s “Central Dogma”: 2-step process by which genes were expressed and proteins were built The Central Dogma: genetic info flows from DNA to RNA to proteins 2-steps: transcription & translation

  11. Translation & Transcription Transcription: from DNA  RNA Translation: from RNA  amino acids

  12. Transcription In the nucleus DNA info is transcribed into a complementary RNA copy

  13. Translation On the ribosomes in the cytosol Assembly of amino acids into a polypeptide using information in RNA

  14. RNA: Ribonucleic Acid RNA: Carrier of genetic information Different from DNA: contains ribose sugar (not de-), uracil and no Thymine and single stranded

  15. RNA: Ribonucleic Acid 3 main types: messenger RNA transfer RNA ribosomal RNA

  16. mRNA Intermediary between the DNA and the ribosomes RNA version of the gene encoded by DNA

  17. tRNA Follows mRNA template Transfers amino acid to the ribosome to build protein

  18. rRNA Structural component of ribosome Along with proteins, it forms the ribosome

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