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GOOD MORNING! HAPPY TUESDAY!

GOOD MORNING! HAPPY TUESDAY!. WARM UP FOR TUES 10/28/14 ADV BIO. What is an anticodon and what is its function? How do ribosomes assist protein synthesis? What would happen if a genetic mutation occurred at a start codon? What happens while tRNA is present at “A SITE”? “P SITE”?.

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GOOD MORNING! HAPPY TUESDAY!

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  1. GOOD MORNING! HAPPY TUESDAY!

  2. WARM UP FOR TUES 10/28/14 ADV BIO • What is an anticodon and what is its function? • How do ribosomes assist protein synthesis? • What would happen if a genetic mutation occurred at a start codon? • What happens while tRNA is present at “A SITE”? “P SITE”?

  3. WARM UP FOR TUES 10/28/14 BIO • Use words to explain what transcription is. Now draw a simple diagram. • What does RNA polymerase do? • What is the role of the promoter in making a copy of RNA? • Differentiate between introns and exons.

  4. From RNA to proteins: Translation

  5. The Central Dogma • DNA-> mRNA-> tRNA->amino acids-> protein • TRANSCRIPTION: from DNA to mRNA • TRANSLATION: from mRNA-> protein

  6. mRNA contains the “message” • RNA contains information (copy of genetic code from DNA) • Process of copying DNA to RNA (transcription) is edited: • Bits of mRNA are removed before final molecule is assembled (introns) • What remains is an mRNA composed of multiple pieces (exons) joined together.

  7. Introns and Exons

  8. CODONS • mRNA is read 3 base pairs at a time, this is called a codon. • Each codon codes for a specific amino acid.

  9. TRANSLATION: THE STEPS • 1. mRNA brings the “message” from the nucleus to the ribosome in the cytoplasm • 2. Ribosome attaches to the mRNA and begins translation at the start codon. mRNA is “fed” through the ribosome one codon (3 bases) at a time. • 3. Transfer RNA (tRNA) molecules carry amino acids to the ribosome. The tRNA (and amino acid) is specific to the codon on mRNA.

  10. tRNAhas 3 unpaired bases called an anticodon that pair specifically with the codon sequence of mRNA

  11. TRANSLATION: THE STEPS • 4. tRNA molecules move through the ribosome. Amino acids are linked together. Empty tRNA discarded. • Translation stops at a stop codon. The protein (amino acid sequence) and mRNA are released from the ribosome.

  12. Translation in Action (video)

  13. “Translation is like a train” • mRNA is the railroad track • tRNA is the railroad car • Amino acids are the cargo in the railroad car

  14. Predicting amino acid sequences • Using a table and base pairing rules for DNA and RNA , we can predict what amino acids are expected from a DNA sequence, or from an RNA sequence. • For example:ATA (DNA) -> UAU (mRNA codon)-> AUA (tRNA anticodon) the tRNA with this anticodon carries the amino acid Tyrosine

  15. Amino acid/ mRNA codon tables

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