1. Ch. 10 Notes DNA: Transcription and Translation

2. GOALS Compare the structure of RNA with that of DNA
Summarize the process of transcription
Relate the role of codons to the sequence of amino acids that results after translation
Outline the major steps of translation
Discuss the evolutionary significance of the genetic code
Describe how the lac operon is turned on or off
Summarize the role of transcription factors in regulating eukaryotic gene expression
Describe how eukaryotic genes are organized
Evaluate three ways that point mutations can alter genetic material

3. Decoding the Information in DNA
RNA
1. Nucleic acid made of nucleotides linked together
2. Single stranded

4. Decoding the Information in DNA
RNA
3. Contains 5C ribose sugar (one more oxygen than DNA)

5. Decoding the Information in DNA
RNA
4. Has A, G and C bases, but no T
5. Thymine replaced by uracils (which pairs with adenine)

6. Decoding the Information in DNA
Transcription
Instructions for making protein are transferred from a gene to an RNA molecule

7. Decoding the Information in DNA
Translation
Two types of RNA are used to read instructions on RNA molecule and put amino acids together to make the protein

8. Decoding the Information in DNA
Gene Expression
Protein synthesis
Protein making process based on information encoded in DNA

9. TRANSCRIPTION Transfers info from a gene on DNA to RNA
In prokaryotes- occurs in cytoplasm
In eukaryotes- occurs in nucleus

10. TRANSCRIPTION Transcription (STEPS)
1. RNA polymerase binds to start signal “promoter” on DNA
2. RNA polymerase unwinds and opens DNA double helix

11. TRANSCRIPTION
Transcription
(STEPS)
3. RNA polymerase reads genes- adds and links matching nucleotides by base pairing (A-U and G-C)

12. TRANSCRIPTION Transcription (STEPS)
4. RNA polymerase reaches stop signal at end of gene
5. As RNA polymerase works, a single strand of RNA grows

13. TRANSCRIPTION
Transcription
(STEPS)
6. DNA helix zips itself back up as RNA polymerase passes by

14. TRANSCRIPTION 7. Many identical RNA molecules are made simultaneously
(STEPS)
7. Many identical RNA molecules are made simultaneously
Feather like appearance in photos

15. The GENETIC CODE Messenger RNA mRNA
Made when cells need a protein made
Delivers protein making instructions from gene to translation site
Instructions written in codons

16. The GENETIC CODE Codons Three nucleotide sequences along mRNA
64 possible codons
Each corresponds to:
An amino acid OR
A stop signal OR
A start signal

17. Can You Tell Me?
1. During DNA replication, what molecule “reads” the strand of DNA to make the matching strand?
2. During transcription, what molecule “reads” the DNA?
3. What material does the transcription process create?

18. The GENETIC CODE RNA’s role in translation Takes place in cytoplasm
Transfer RNA (tRNA) and ribosomes help in protein synthesis

19. The GENETIC CODE Transfer RNA tRNA Single strand, carries amino acid
Folded shape
Contains anticodon

20. The GENETIC CODE Anticodon
3 nucleotides on tRNA that are complementary to a mRNA codon

21. The GENETIC CODE
Ribosomal RNA
rRNA makes up part of ribosomes

22. The GENETIC CODE Translation process
1. mRNA leaves nucleus, enters cytoplasm
2. Ribosome hooks onto mRNA at start codon

23. The GENETIC CODE Translation process
3. tRNA attaches to ribosome subunit and binds to mRNA
Anticodon of tRNA binds to codon of mRNA

24. The GENETIC CODE Translation process
4. tRNA drops off amino acid its carrying
5. Another tRNA comes and drops an amino acid off

25. The GENETIC CODE Translation process
6. Another tRNA enters, first tRNA leaves

26. The GENETIC CODE Translation process
7. Each amino acid bonded to previous one to form a chain
tRNA detaches leaving
amino acid attached to
remaining tRNA

27. The GENETIC CODE Translation process
9. Repeats until ribosomal subunit reaches stop codon
10. Newly made protein is released

28. TRANSLATION

29. TRANSLATION

30. TRANSLATION

31. TRANSLATION

32. TRANSLATION

33. Assessment One
Distinguish two differences between RNA structure and DNA structure
Explain how RNA is made during transcription
Interpret the genetic code to determine the amino acid coded for by the codon CCU
Compare the roles of the three different types of RNA during translation
What is the maximum number of amino acids that could be coded for by a section of mRNA with the sequence GUUCAGAACUGU?

34. Protein Synthesis
Protein Synthesis in Prokaryotes
Requires too much energy and too many materials for cell to make every protein encoded for by the DNA at all times
Gene expression can be regulated according to cell needs
Ex: E. coli bacteria

35. Regulating Protein Synthesis
Lac Operon
1. Lactose in dairy products enters your intestines
2. E. coli there can use lactose for nutrition (to make glucose and galactose)

36. Regulating Protein Synthesis
Lac Operon
3. Three genes for breaking down lactose located next to each other on DNA (can turn them on or off)
Genes on: they’re ready to be transcribed and translated

37. Regulating Protein Synthesis
Lac Operon
4. These 3 genes turn on in presence of lactose and turn off in its absence

38. Regulating Protein Synthesis
Lac Operon
5. Operator- area on DNA (touching start/promoter) that acts as on and off switch
Can block RNA polymerase from transcribing

39. Regulating Protein Synthesis
Lac Operon
6. Operon consists of
Operator
Promoter
Three genes
All work together to control lactose metabolism

40. Regulating Protein Synthesis
Lac Operon
7. No lactose present
Lac operon is turned off when repressor protein binds to DNA
Repressor blocks RNA polymerase from binding

41. Regulating Protein Synthesis
Lac Operon
8. In presence of lactose
Lactose binds to repressor changing its shape
Causes repressor to fall off DNA
Allows RNA polymerase to bind and transcribe

43. Regulating Protein Synthesis
Protein synthesis in eukaryotes
Most gene regulation is to control the onset of transcription (binding of RNA polymerase)

44. Regulating Protein Synthesis
Protein synthesis in eukaryotes
Transcription Factors- regulatory proteins that help rearrange RNA polymerase into the correct position

45. Intervening DNA Intervening DNA in Eukaryotic Genes
1. Introns- longs segments of nucleotides with no coding information
Break up DNA/genes

46. Intervening DNA Intervening DNA in Eukaryotic Genes
2. Exons- actual genes that are translated into proteins

47. Intervening DNA Intervening DNA in Eukaryotic Genes
3. After transcription, introns in mRNA are cut out by spliceosomes
Exons are stitched back together

48. Intervening DNA Intervening DNA in Eukaryotic Genes
4. Large numbers of exons and introns allows evolutionary flexibility because they can be shuffled about to make new genetic codes

50. Mutations Mutations Changes in DNA of a gene are rare
When in body cells, only affect individual
When in gametes, offspring can be affected

51. Mutations
Mutations
A. Gene rearrangements- entire gene moved to a new location (disrupts its function)

52. Mutations Mutations B. Gene alterations- changes a gene
Usually results in wrong amino acid being hooked into protein (disrupts protein function)

53. Mutations
Mutations
C. Point Mutation- single nucleotide changes

54. Mutations
Mutations
D. Insertion Mutation- extra piece of DNA is inserted

55. Mutations
Mutations
E. Deletion Mutation- segments of gene are lost

56. Mutations
Mutations
F. Frame shift Mutations- causes gene to be read in wrong 3 nucleotide sequence
Ex THE CAT ATE
Remove C
THE ATE TE (makes no sense)

58. WEBSITES DNA Workshop Transcription
Interactive Transcribing and Translating a Gene
Protein Synthesis Animation
Transcription Animation
Translation Movie
Protein Translation Animation
Animation of Translation
Protein Synthesis Movie
Transcription Game
Protein Synthesis Tutorial