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Transcription. a.k.a “The RNA Lecture”. Genes in the DNA sequence encode information about proteins and how those proteins are assembled DNA is stored in the _______________ Proteins are made at the ____________. nucleus. ribosome. Does anyone see a problem?. NUCLEUS. DNA. Ribosome.

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  1. Transcription a.k.a “The RNA Lecture”

  2. Genes in the DNA sequence encode information about proteins and how those proteins are assembled • DNA is stored in the _______________ • Proteins are made at the ____________ nucleus ribosome Does anyone see a problem?

  3. NUCLEUS DNA Ribosome • DNA never leaves the nucleus and the ribosomes never enter the nucleus.

  4. Key Point: If the cell wants the information stored in DNA to be expressed as protein, we need to have a messenger take the information from the nucleus to the ribosome. • The messenger that the cell uses is called RNA Ribonucleic Acid

  5. BASES a. Cytosine b. Guanine c. Adenine d. Uracil

  6. SUGAR • Yes, there is still a phosphate • # of strands = Ribose 1

  7. DIFFERENCES BETWEEN DNA AND RNA 2 1 Ribose Deoxyribose A, T, C, G A, U, C, G Only in nucleus Nucleus, cytoplasm, ribosome

  8. HOW IS RNA MADE? Transcription – video link

  9. What must be present during transcription? a. DNA gene gene – DNA sequence which codes for a protein b. ribonucleotides c. RNA Polymerase

  10. What are the steps of transcription? a. DNA separates at gene b. RNA polymerase transcribes gene strand to RNA c. DNA strands reconnect; RNA leaves for ribosome

  11. A T T A G C A T C G A – T – G – A – C – U A C U G - T - A - C - T - G A – T T – A G – C A – T C - G A – T T – A G – C A – T C - G DNA is unzipped DNA strands reform double helix Copy Gene Gene strand is transcribed

  12. Where does transcription take place? In the nucleus

  13. How does RNA Polymerase know where to start and stop transcription? Starts at a DNA sequence called the “promoter” Stops at a DNA sequence called the “terminator” Promoter Gene Terminator Video Links – original new

  14. Where does RNA go after transcription? Heads to ribosome so the code can be used to build protein • What types of RNA does a cell make? • mRNA – • rRNA – • tRNA – messenger RNA; copy of DNA gene sent to ribosome Let’s come back to the rest later

  15. What happens to RNA after it leaves the nucleus? The rest of protein synthesis

  16. What happens to mRNA after it leaves the nucleus and how does mRNA actually help a cell make proteins? Translation –Let’s go to the animation!

  17. What’s “Met” and “Arg”? Amino Acids

  18. What are the main steps in translation? 1. mRNA reaches ribosome 2. Ribosome scans for a place to start – “start codon”

  19. What is a codon? Codon – 3 bases in mRNA which code for 1 amino acid ACG = CGA = UCG =

  20. What is a codon? Codon – 3 bases in mRNA which code for 1 amino acid GAU = AUG = UAG, UGA, UAA =

  21. What are the main steps in translation? 3. tRNA with correct anti-codon brings amino acid to ribosome tRNA – transfer RNA; brings amino acids to ribosome Anti-codon – 3 bases in tRNA; complimentary to codon Ex. Anti-codon = AUG, codon = UAC

  22. What are the main steps in translation? 4. tRNA with correct anticodon for next codon brings its amino acid into place 5. Peptide bond forms between amino acids

  23. What are the main steps in translation? 6. Process continues until ribosome reaches a stop codon

  24. What happens to proteins after they are synthesized? • Proteins for inside of cell: • Folded into correct shape in cytoplasm • Proteins for outside of cell: • Folded into correct shape in ER • Further processed by Golgi Body • Exported from cell by exocytosis

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