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THE BIG IDEA!!!!!!!

THE BIG IDEA!!!!!!!. Transcription. From DNA to RNA. What is RNA?. Ribonucleic acid (RNA). Structure of RNA. 1 strand Phosphate group 5 carbon Sugar ( ribose ) Nitrogen base. What are the bases?. Adenine (A) Guanine (G) Cytosine (C) Uracil (U). Which are purines?.

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THE BIG IDEA!!!!!!!

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  1. THE BIG IDEA!!!!!!!

  2. Transcription From DNA to RNA

  3. What is RNA? • Ribonucleic acid (RNA)

  4. Structure of RNA • 1 strand • Phosphate group • 5 carbon Sugar (ribose) • Nitrogen base

  5. What are the bases? • Adenine (A) • Guanine (G) • Cytosine (C) • Uracil (U)

  6. Which are purines? • Adenine and Guanine • 2 rings

  7. Which are pyrimidines • Cytosine and Uracil • 1 ring

  8. Which bases pair? • A, U • G, C • When transcribing RNA, U replaces T

  9. Step one • RNA polymerase binds at a promoter • A region of DNA that says start

  10. Step 2 • RNA polymerase unwinds the DNA • Exposes the nucleotides

  11. Step 3 • RNA polymerase adds complimentary RNA nucleotides

  12. When is transcription finished? • RNA polymerase reaches the stop signal and detaches from the DNA • RNA is released • DNA double helix Reforms Watch

  13. Does RNA polymerase transcribe all of the DNA? • NO • Uses one part of one strand of DNA (the gene)

  14. Does all the DNA transcribed code for proteins? • NO! • Introns • Long segments of “junk” DNA that have no coding info.

  15. What DNA does code for proteins? • Exons • DNA that codes for proteins

  16. When are the Introns removed? • Before the mRNA leaves the nucleus • An enzyme cuts out the introns & puts exons together

  17. Materials: masking tape, pens or pencils (two colors), metric ruler, scissors Procedure Place a 15-20cm piece of masking tape on your desk. This represents a gene Use two colors to write appropriatelyjoined One color represents introns, one exons Space the letters so they take up the entire piece of tape Lift the tape Working from left to right cut apart the groups of letters in the same color Stick the pieces to a piece of paper as you cut them making two strips according to color. Join the pieces in their original order. 1. Label the strand that is the intron and label the strand that is the exon. 2. Predict what might happen to a protein if an intron were not removed. Turn into the box. ACTIVITY

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