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BELLRINGER:

BELLRINGER:. Draw the following box and fill in the squares:. REPLICATION. TRANSCRIPTION. Where in the cell does this take place?. Where in the cell does this take place?. What is created in this process?. What is created in this process?. WHY does this take place?.

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BELLRINGER:

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  1. BELLRINGER: Draw the following box and fill in the squares: REPLICATION TRANSCRIPTION Where in the cell does this take place? Where in the cell does this take place? What is created in this process? What is created in this process? WHY does this take place? WHY does this take place?

  2. THE THREE TYPES OF RNA

  3. There are three types of RNA that help build proteins. Section 11.2 Summary – pages 288 - 295 # 1 Messenger RNA (mRNA) brings instructions from DNA in the nucleus to the cytoplasm. Then mRNA binds to ribosomes.

  4. Section 11.2 Summary – pages 288 - 295 # 2 Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids (the building blocks of proteins) to the ribosome to be assembled into a protein. Amino Acid How it binds with mRNA

  5. # 3 Ribosomes are made of Ribosomal RNA (rRNA). Section 11.2 Summary – pages 288 - 295 rRNA uses the instructions from mRNA and the supplies from tRNA to assemble the amino acids in the correct order.

  6. mRNA brings the instructions. • tRNA supplies the amino acid parts. • rRNA builds the proteins using the instructions and amino acids. RIBOSOME

  7. THE PROCESS OF TRANSLATION

  8. Protein Synthesis Transcription Translation

  9. Why does mRNA have to be made? (Why can’t DNA deliver it’s own instructions) Section 11.2 Summary – pages 288 - 295 Nucleus

  10. The Genetic Code Section 11.2 Summary – pages 288 - 295 • Every three letters on a mRNA strand, called a codon, is a code for a specific amino acid (a building block to make protein)

  11. Every three letters on an mRNA strand is a codon. Each codon codes for a specific amino acid. CODON CHART Things to notice: There are 64 possible codon combinations There are only 20 different amino acids Most amino acids correspond to more than one codon

  12. Translation changingnucleic acid languagetoamino acid language

  13. Step 1: Section 11.2 Summary – pages 288 - 295 • As translation begins, the “capped” end of mRNA strand attaches to a ribosome. mRNA strand Ribosome

  14. tRNA’s role Section 11.2 Summary – pages 288 - 295 • tRNAs bring amino acids to the ribosomes. mRNA Coming from Nucleus RIBOSOME

  15. Each tRNA only carries one amino acid. Amino acid

  16. There are also three nucleotides on the bottom of the tRNA called an anti-codon. • Anti-codons complementary base pair with the codons on mRNA. (this is to make sure they are bringing the correct amino acid- If the anti-codon doesn’t base pair with the codon, then the wrong amino acid was brought) Section 11.2 Summary – pages 288 - 295 Anti-codon

  17. Step 2: Initiation • AUG is usually the first codon on the mRNA strand. • This signals the ribosome to START making a protein. Section 11.2 Summary – pages 288 - 295 Methionine • The initiator tRNA with anticodon UAC comes and binds with this codon and drops off it’s amino acid “Methionine”.

  18. After the first tRNA binds with its codon, the mRNA slides down so that the ribosome can read the next codon. Section 11.2 Summary – pages 288 - 295

  19. A new tRNA molecule carrying an amino acid pairs with the second mRNA codon. Section 11.2 Summary – pages 288 - 295 Alanine

  20. The amino acids then bond together. What kind of bond is it? • Once the first tRNA lets go of it’s amino acid, it is released from the ribosome. Section 11.2 Summary – pages 288- 295 PEPTIDE BOND Methionine Alanine bond

  21. Step 3: Elongation • Refers to the time that the amino acid chain (poly-peptide) is being built or “elongated”. Section 11.2 Summary – pages 288- 295

  22. Step 4: Termination • A chain of amino acids is formed until the stop codon is reached on the mRNA strand. Section 11.2 Summary – pages 288 - 295 The end result is a protein Stop codon

  23. Ribosomes • A site (aminoacyl-tRNA site) • holds tRNA carrying next amino acid to be added to chain • P site (peptidyl-tRNA site) • holds tRNA carrying growing polypeptide chain • E site (exit site) • empty tRNA leaves ribosome from exit site Met C A U 5' G U A 3' E P A

  24. The Wobble Effect Look at your codon chart and find an example of different codons that code for the same amino acid. For codon-anticodon interactions, the third base of the codon isn’t read as “strictly” in the DNA/mRNA sequence during transcription or DNA replication. CUU; CUC; CUA This is called the wobble effect. As long as the first two bases are the same, the last base doesn’t matter all that much. Each of these mRNA codon sequences will bond with a single type of tRNA that carries leucine.

  25. Prokaryotes DNA in cytoplasm circular chromosome naked DNA no introns Eukaryotes DNA in nucleus linear chromosomes DNA wound on histone proteins introns vs. exons intron = noncoding (inbetween) sequence exon = coding (expressed) sequence Prokaryote vs. Eukaryote genes eukaryotic DNA

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