1. Welcome to class 1/19/16 – 1/20/16  Turn in Check for understanding (3 of them)  Warm up 16-20  Notes on RNA and Transcription process  Complete check for understanding  HomeFun: Genetic Code SkillSheet  Reminder: DNA project due Feb 1 st and 2 nd

2. RNA

3. 3 Transcription Translation DNA mRNA Ribosome Protein Prokaryotic Cell DNA  RNA  Protein

4. 4 Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell

5. Types of RNA The three main types of RNA are: Messenger RNA Ribosomal RNA Transfer RNA

6. Messenger RNA  An mRNA molecule is a copy of the portion of DNA that will be used to make a protein.  After being made in the nucleus, mRNA travels to the cytoplasm, the site of protein synthesis.

7. Ribosomal RNA  Protein synthesis occurs on ribosomes, which are made up of two subunits.  Both subunits consist of several molecules of ribosomal RNA (rRNA).

8. Transfer RNA During protein synthesis, transfer RNA molecules (tRNA) carry amino acids from the cytoplasm to the mRNA.

9. 9. Three Types of RNA Messenger RNA (mRNA) carries genetic information to the ribosomes Messenger RNA (mRNA) carries genetic information to the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

10. RNA Synthesis: Transcription In transcription, segments of DNA serve as templates to produce complementary mRNA molecules.

11. RNA Synthesis: Promoters RNA polymerase binds only to regions of DNA that have specific base sequences. These regions are called promoters. C A G U T A

12. RNA Processing Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell

13. RNA Synthesis: RNA Editing New RNA molecules sometimes require a bit of editing before they are ready to be read. Introns Exons CapTail Introns exons Introns are pulled out and exons come together. mature RNA molecule nucleus cytoplasm. End product is a mature RNA molecule that leaves the nucleus to the cytoplasm.

14. 14 RNA Processing pre-RNA molecule intron exon Mature RNA molecule exon intron splicesome

15. Check for understanding 1.Compare and contrast DNA and RNA following my chart 2.What are the 3 types of RNA? Draw each type and describe their function 3.What is transcription? Where does it occur? Describe step by step process and draw a picture of transcription 4.Contrast Intron and Extron

16. Ribosomes and Protein Synthesis

17. Importance of proteins: 1.break down food to power your muscles 2. send signals through your brain that control the body 3. transport nutrients through your blood. Proteins are building blocks, they make up all that you are.

18. 18 Translation Synthesis of proteins in the cytoplasm Synthesis of proteins in the cytoplasm Involves the following: Involves the following: 1.mRNA (codons) 2.tRNA (anticodons) 3.ribosomes 4.amino acids

19. 19 Transcription Translation DNA mRNA Ribosome Protein Prokaryotic Cell DNA  RNA  Protein

20. 20 DNA  RNA  Protein Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell

21. The Genetic Code RNA has four bases: adenine, cytosine, guanine, and uracil. These bases form a “language”: A, C, G, and U.

22. The Genetic Code: Codons  The genetic code is read in three-letter groupings called codons.  A codon is a group of three nucleotide bases in messenger RNA that specifies a particular amino acid. AUG AAC UCU

23. Genetic Code Table There are 64 possible three-base codons in the genetic code.

24. Reading Codons Start at the middle of the circle with the first letter of the codon and move outward. CAC = Histidine

25. Start and Stop Codons The methionine codon AUG serves as the “start” codon for protein synthesis. There are three “stop” codons. AUG = methionine = “start” codon UAA, UAG, and UGA are “stop” codons

26. Codon Chart: This rectangular chart his on EOC EXAM, not the circle one 1.AAA is a codon that encoded for what amino acid? 2.CUA?

27. Translation  Transcribed mRNA directs the translation process.  Translation is the process that makes proteins using the copy of the DNA code on the mRNA.

28. Translation: Transfer RNA To start translation, tRNA molecules bind to mRNA codons, carrying amino acids with them. anticodon

29. Translation: The Polypeptide Assembly The ribosome helps form a peptide bond. It breaks the bond holding the first tRNA molecule to its amino acid.

30. Translation: Completing the Polypeptide The ribosome reaches a stop codon, releasing the newly synthesized polypeptide and the mRNA molecule, completing the process of translation.

31. Roles of RNA in Translation All three major forms of RNA—mRNA, tRNA, and rRNA—are involved in the process of translation.

32. The Molecular Basis of Heredity The central dogma of molecular biology is that information is transferred from DNA to RNA to protein.

33. Gene Expression When a gene (segment) of DNA code is used to build a protein, scientists say that gene has been expressed.

34. Check for understanding 1.What is the purpose of translation? Describe the process of translation in steps 2.Draw and label 3 types of RNAs including their structures and functions 3.What is a codon? What is an anticodon?

35. Student Worksheet Answers