1. From Gene to Protein Transcription & Translation

2. AN OVERVIEW

3. Mobility Problem DNA cannot leave the nucleus.DNA cannot leave the nucleus. Proteins are made in the cytosolProteins are made in the cytosol How to connect the 2?How to connect the 2?

4. Transcription RNA can leave the nucleus.RNA can leave the nucleus. Similar structure to DNA, exceptSimilar structure to DNA, except –Only one-stranded –Does not have Thymine (T). Has Uracil (U) instead. –Ribose for its sugar instead of deoxyribose.

5. mRNA (messenger RNA) is transcribed according to instructions of the coding strand of DNA.

6. mRNA can then carry the message of the DNA to the ribosome in the cytosol!

7. Language Problem Language of DNA- 4 bases, A, T, G, & CLanguage of DNA- 4 bases, A, T, G, & C Language of Proteins- 20 amino acids.Language of Proteins- 20 amino acids. How to translate?How to translate?

8. Translation Synthesis of a polypeptide, under the direction of the translator  RNASynthesis of a polypeptide, under the direction of the translator  RNA Occurs in cytosol, at the ribosome.Occurs in cytosol, at the ribosome.

9. Every 3 nucleotides code for the production of a specific amino acid.

10. Transcription A Closer Look

11. 1.RNA polymerase separates 2 strands of DNA a)It then hooks RNA nucleotides together as they match to DNA template. b)5’  3’

12. 2. Polymerase attaches to sequence of DNA called promoter. 3. Sequence that signals end of transcription is called terminator.

13. Which strand of DNA to transcribe?

14. Modifying RNA Both ends of the RNA sequence are altered.Both ends of the RNA sequence are altered. –5’ end is capped with a modified Guanine –3’ end is capped with a poly-A tail.

15. More Modification RNA splicingRNA splicing –Initial RNA sequence is approximately 8,000 nucleotides –Generally, only approx. 1,200 are needed, though. –Noncoding areas are found in between coding areas

16. Introns - Noncoding region Exons - Coding region of nucleic acid

17. How are introns found & cut out? snRNPs (“snurps”) recognize the end of an intronsnRNPs (“snurps”) recognize the end of an intron They then form a spliceosome with other proteins and cut out that intronThey then form a spliceosome with other proteins and cut out that intron

18. Translation A closer look

19. What’s a triplet code? Flow of information from gene (DNA) to protein is a triplet codeFlow of information from gene (DNA) to protein is a triplet code Every 3 nucleotides will code for the production of a specific amino acid.Every 3 nucleotides will code for the production of a specific amino acid. mRNA base triplets are called codons.mRNA base triplets are called codons.

20. The purpose of tRNA. Interpreter of the mRNA codons is tRNA (transfer RNA)Interpreter of the mRNA codons is tRNA (transfer RNA) Each tRNA molecule has a section called the anticodon.Each tRNA molecule has a section called the anticodon. tRNA grabs a specific amino acid & brings it to the ribosometRNA grabs a specific amino acid & brings it to the ribosome

21. How do mRNA & tRNA work together to get the correct amino acid? Anticodon of tRNA meets with the codon of mRNA at the ribosome.Anticodon of tRNA meets with the codon of mRNA at the ribosome. –Ex- mRNA codon UUU - tRNA anticodon- AAA - tRNA anticodon- AAA - tRNA will have phenylalanine to add to the polypeptide

22. FirstFirst Study ribosomes, p. 316.Study ribosomes, p. 316. Second Study Building a Polypeptide, p. 317-318