1. Lesson 5: Transcription & Translation
LT: Be able to explain the process of DNA transcription.

2. THE BIG PICTURE!!!
Transcription
Translation
DNA
RNA
protein

3. Notes from reading pgs. 425-426
RNA = ribonucleic acid
Made of nucleotides
Sugar in nucleotides is ribose
RNA uses uracil instead of thymine
RNA is single-stranded and not double stranded
mRNA = messenger RNA
Carries the message of DNA from the nucleus to the cytoplasm to be made into a protein
Transcription: the process by which DNA is copied into a complementary RNA molecule

4. Process & Procedure: Modeling Transcription
Create a double stranded DNA molecule that is 15 bases long
Our Code:
RED = adenine (A)
BLUE = thymine (T)
YELLOW = cytosine (C)
GREEN = guanine (G)
BLACK = uracil (U)
Work through step #3a-f

5. Stop & Think
How is DNA transcription like DNA replication? How are the 2 processes different?
In this activity, you transcribed 2 different DNA strands. Each one was only 15 nucleotides long. That seems pretty short.
a. How many different arrangements of nucleotides are possible in a strand of DNA that is 15 nucleotides long?
Same: complementary bases, DNA acts as a template
Different: transcription uses uracil, replication uses thymine
4^15 = 1,073,741,824 possibilities

6. How would the number in 2a compare with the number of different arrangements of nucleotides possible in a real strand of DNA?
4^80,000,000 is a ridiculously HUGE number

7. Notes on DNA transcription

8. Do the cells in your eye and your tongue have the same functions?
Do the cells in your eye and your tongue have the same proteins?

9. Do the cells in your eye and your tongue have the same DNA?

10. What have we learned?
Proteins determine most characteristics of a cell and organism
Information stored in DNA determines which proteins can be made by a cell
The environment influences which proteins are made by a cell

11. Where is protein made in a cell?

12. DNA does not leave the nucleus of eukaryotic cells
DNA does not leave the nucleus of eukaryotic cells... but proteins are made outside of the nucleus by ribosomes
Elodea leaf cell
human cheek
cell
mitochondria
chloroplasts
vacuole
nucleus
(DNA here)
(DNA here)

13. DNA does not leave the nucleus of eukaryotic cells
DNA does not leave the nucleus of eukaryotic cells... but proteins are made outside of the nucleus by ribosomes
ribosomes
(proteins made here)
(proteins made here)
nucleus
(DNA here)
(DNA here)

14. DNA and ribosomes are at different locations in a prokaryoic cell.
E. coli bacteria cell
ribosomes
(proteins made here)
DNA

15. Information flow from DNA to trait
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus
So how does DNA get turned into a protein if it can’t leave the nucleus???

16. messenger RNA
mRNA transfers information from the DNA in the nucleus to the ribosomes.
mRNA is made in the nucleus and then travels to the cytoplasm through nuclear pores
Ribosomes build proteins according to the mRNA information received.

17. Information flow from DNA to trait
messenger
RNA
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus

18. DNA information  mRNA information
messenger
RNA
DNA
Transcription is the process used to convert DNA information into mRNA information.
Note: DNA does not become RNA; the information in DNA is copied as RNA

19. RNA is different than DNA
Single strand of nucleotides
Contains uracil (U) instead of thymine (T)
Made of the 5-Carbon sugar Ribose instead of deoxyribose (DNA)

20. Difference between DNA and RNA
5-Carbon Sugar: deoxyribose
5-Carbon sugar:
Ribose
A,T,C,G
A,U,C,G
Double stranded
Single stranded

21. Different Sugars DNA RNA Can you spot the difference?
RNA
Can you spot the difference?

22. Different Bases Can you spot the difference?
Can you spot the difference?

23. DNA- double stranded
RNA- single stranded

24. RNA and DNA Nucleotides
Remember – DNA has A-T or T-A; and G-C or C-G
RNA has uracil instead of Thymine and the bases are not in pairs
DNA

25. DNA (double stranded original, protected in nucleus)
RNA IS COPIED FROM DNA
DNA
(double stranded original, protected in nucleus)
COPIED
RNA
(single strand - mobile)

26. mRNA: the messenger
RNA is how the body gets information from the nucleus (DNA) to the place where
protein gets made (ribosomes)

27. 3 Types of RNA mRNA: messenger RNA tRNA: transfer RNA
rRNA: ribosomal RNA

28. THE BIG PICTURE!!!
Transcription
Translation
DNA
RNA
protein

29. http://fajerpc. magnet. fsu

30. Transcription
Molecule of DNA is copied into a complimentary mRNA strand

31. RNA Polymerase RNA polymerase is an enzyme
Attaches to promoters (special sequences on the DNA)
Unzips the two strands of DNA
Synthesizes the mRNA strand

32. Steps of Transcription
Step 1: RNA polymerase attaches to DNA
Step 2: RNA polymerase unzips DNA
Step 3: RNA polymerase hooks together the nucleotides as they base-pair along the DNA template
Step 4: Completed mRNA strand leaves the nucleus

33. Transcription

34. If the DNA code is this: TACGAGTTACATAAA ATGCTCAATGTATTT
What is the mRNA code?
Use the bottom strand as the template for mRNA
UACGAGUUACAUAAA

35. Which proteins are made in a cell?
Controlled by activator molecules
Bind to enhancers (segments of DNA)
“Turns on” transcription of the gene
Example: Arabinose and araC protein

38. Information flow from DNA to trait
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus

39. Information flow from DNA to trait
messenger
RNA
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus
Transcription
Transcription Video

40. Part II: Translation
LT: Be able to explain the process of translation.

41. THE BIG PICTURE!!!
Transcription
Translation
DNA
RNA
protein

42. Information flow from DNA to trait
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus

43. Information flow from DNA to trait
messenger
RNA
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus
Transcription

44. Information flow from DNA to trait
messenger
RNA
Observed trait
DNA
protein
Made by ribosomes outside of nucleus
Stored in nucleus
Translation

45. mRNA information  protein
messenger
RNA
protein
Translation is the process used to convert mRNA information into proteins.
- also known as “protein synthesis”
Note: mRNA does not become a protein, the information on mRNA is “read” and ribosomes assemble proteins from this code

46. Translation Ribosomes use mRNA as a guide to make proteins
Ribosomes use mRNA as a guide to make proteins

47. 4 Components used in Translation
mRNA- the message to be translated into protein.
Amino acids- the building blocks that are linked together to form the protein.
Ribosomes- the “machines” that carry out translation.
tRNA (transfer RNA)- brings an amino acid to the mRNA and ribosome.

48. The message mRNA is a strand of nucleotides
Ex. AUGCCGUUGCCA…
Each combination of three nucleotides on the mRNA is called a codon

49. tRNA Transfer RNA Single strand of RNA that loops back on itself
Has an Amino Acid attached at one end
Amino Acids are the building blocks of proteins
Has an anticodon at the other end

50. What is an anticodon?
The anticodon is a set of three nucleotides on the tRNA that are complimentary to the codon on the mRNA

51. The Ribosome

52. Steps of Translation Step 1: mRNA binds to ribosome
Step 2: tRNA anticodon attaches to the first mRNA codon
Step 3: the anticodon of another tRNA binds to the next mRNA codon
Step 4: A peptide bond is formed between the amino acids the tRNA molecules are carrying.

53. Translation

54. Steps of Translation cont.
Step 5: After the peptide bond is formed, the first tRNA leaves. The ribosome moves down to the next codon.
Step 6: This process continues until the ribosome reaches a stop codon.
Step 7: The chain of peptides (protein) is released and the mRNA and ribosome come apart.

55. Translation

56. Remember…
mRNA nucleotides are translated in groups of 3 called codons.
AUGCACUGCAGUCGAUGA
CODONS

57. Decoding the message…
Each codon codes for a specific amino acid. 20 different amino acids can be used in different combinations to form a protein.
For example:
mRNA codon amino acid
AAU asparagine
CGC arginine
GGG glycine

58. The Genetic Code

59. Simulation! I need 6 volunteers who don’t mind holding hands. 
And then one more volunteer.
Translation Video

60. Amino Acid sequence determines the 3-D protein shape
Interactions between amino acids cause folding and bending of the chain
Examples:
positive (+) and negative (-) parts of amino acids are attracted to each other.
hydrophobic regions are attracted to each other
Folding
Structure levels
structure.swf

61. How is the amino acid sequence determined?
The mRNA
Each codon is a code for one amino acid
DNA sequence: T A C C G A G A T T C A
mRNA sequence: A U G G C U C U A A G U
amino acid sequence: Met -- Ala -- Leu -- Ser
Whole Process Video

62. Special Codons
Start codon: AUG
Stop codons: UAA, UGA, UAG

63. Your turn:
For each of the codons below, determine the amino acid it corresponds with:
AUG: Methionine (Met)
CCA: Proline (Pro)
UUG: Leucine (Leu)
GCA: Alanine (Ala)
UAG: STOP!

64. The Activity My desk: NUCLEUS Your desk space is the CYTOPLASM
In your group of 3, decide who will be:
mRNA: transcribes the DNA template and delivers the message to the cytoplasm
rRNA: makes up the ribosome and interprets the message in codons
tRNA: brings correct amino acids to the ribosome using anticodons

65. Steps:
1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

66. Share sentences in order

67. Repeat steps, but change roles for round 2.
1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

68. Share sentences in order

69. Repeat steps, but exchange roles for round 3.
1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

70. Share sentences.

71. Follow-up Questions:
What do the following analogies from the simulation represent in a real cell?
Words
Sentence
What may have happened in round 3 of the simulation to give us the outcomes we got?
Do you think this happens in nature?
Amino Acids
Proteins (polypeptides)