1. Protein Synthesis Learning Outcomes – B7 and B8
Overview and Application

2. Try This!
1) One strand of DNA has the following sequence: A T T C G A C G G What is the corresponding sequence of RNA?
2) If this new RNA is transported out of the nucleus directly to a ribosome, which of the three types of RNA is it?

3. Overview Learning Outcome B7 - 1 It is expected that students will:
Molecular Biology’s central dogma: replication, transcription, translation, assembly: Howard Hugh’s Medical
It is expected that students will:
- identify the roles of DNA, messenger RNA, transfer RNA and ribosomes in the processes of transcription and translation including initiation, elongation and termination.

4. Overview What are the two stages of Protein Synthesis?
1) Transcription
2) Translation

5. Transcription
DNA is used as a template to form a molecule of single-stranded mRNA (messenger RNA)

6. Transcription
Three steps: 1) DNA unzips 2) Complimentary base pairing of ribonucleotides 3) Termination

7. Transcription – 1) Unzip
One section of DNA is unzipped (H-bond between nitrogen bases are broken)

8. Transcription – 2) Complimentary
Free-floating ribo-nucleotides temporarily hydrogen bond with their complimentary nucleotides on the DNA template
Only one of the DNA strands is used as the template.
Ex: DNA – A T C G RNA –

9. Transcription - Termination
RNA polymerase reaches termination sequence
RNA polymerase detaches from DNA, releasing single-stranded RNA strand
DNA rewinds into its double helix
mRNA is transported out of the nucleus

10. Translation
mRNA goes to the ribosome and is used as a template to synthesize a protein molecule.

11. Translation
Three Steps:
1) Initiation
2) Elongation
3) Termination

12. Translation – 1) Initiation
need start codon AUG
The first tRNA, with anticodon UAC and amino acid methionine temporarily binds to the first site

13. Translation – 2) Elongation
The second tRNA molecule attaches to the second site of translation.

14. Translation – 2) Elongation
The amino acid from the first tRNA is transferred to the amino acid on the second tRNA.

15. Translation – 2) Elongation
The first tRNA exits, the ribosome moves, a new tRNA enters, and the process is repeated.

16. Translation – 2) Elongation
The process is repeated many times, and a peptide, or strand of amino acids, is formed.

17. Translation – 3) Termination
The release factor enters.
Translation, or protein synthesis, ends.

18. Translation – 3) Termination
The completed polypeptide is released.

19. Translation - Application
What does this diagram represent?
- Translation
- ELONGATION

20. Application Learning Outcome B7 - 2 It is expected that students will:
- determine the sequence of amino acids coded for by a specific DNA sequence, given a table of mRNA codons.

21. Application – table of mRNA codons (p 511)

22. Application
Consider the following DNA base sequence read from left to right:
T A C G C A A A A T G G
Determine the amino acid sequence that results from this DNA strand – put the answer on the next slide.

23. Application methionine – arginine – phenylalanine – threonine
DNA sequence:
T A C G C A A A A T G G
mRNA sequence:
A U G C G U U U U A C C
Animo acid sequence:
methionine – arginine – phenylalanine – threonine

24. Application PLO B7 – 3 It is expected that students will:
Identify the complementary nature of the mRNA codon and tRNA anti-codon

25. Application
Which of the following is an anticodon of a molecule of tRNA carrying glycine?
A. G G A
B. C C U
C. C C T
D. C G C

26. Application
Which of the following is an anticodon of a molecule of tRNA carrying glycine?
Amino acid: glycine
mRNA codon: GGU/GGC/GGA/GGG
tRNA anticodon: CCA/CCG/CCU/CCC

27. Application B. C C U < ANSWER!
Which of the following is an anticodon of a molecule of tRNA carrying glycine?
A. G G A
B. C C U < ANSWER!
C. C C T
D. C G C

28. Application Learning Outcome B8 -2 It is expected that students will:
- use examples to explain how mutations in DNA change the sequence of amino acids in a polypeptide chain and as result may lead to to genetic disorders.

29. Definitions gene mutation:
A change in the sequence of bases within a gene

30. Definitions – Gene Mutations
frameshift mutations
One or more nucleotides is inserted or deleted from the DNA
Example: TAC GGT TAG, insert C into the 4th spot:
TAC CGG TTA G
The original DNA coded for which amino acids?
DNA: TAC GGT TAG
mRNA: AUG CCA AUC
amino acids: methionine – proline - isoleucine
The mutated DNA now codes for which amino acids?
DNA: TAC CGG TTA G
mRNA: AUG GCC AAU C
animo acids: methionine – alanine - asparagine

31. Definitions – Gene Mutations
point mutations
a change in a single nucleotide within the sequence
Example: TAC GGT TAG, replace 2nd T with a C
TAC GGC TAG
The original DNA coded for which amino acids?
DNA: TAC GGT TAG
mRNA: AUG CCA AUC
amino acids: methionine – proline - isoleucine
The mutated DNA now codes for which amino acids?
DNA: TAC GGC TAG
mRNA: AUG CCG AUC
animo acids: methionine – proline - isoleucine

32. Definitions - Gene Mutation
What effect does changing the amino acids have on the protein product?
Changes the shape. Since shape determines function, it alters how the protein will function.

33. Proteins: Shape determines Function!

34. Definitions - Gene Mutation
Which has the potential for the most damage, frameshift mutations or point mutations?
Frameshift

35. Application Learning Outcome B8 - 1 It is expected that students will:
- give examples of two environmental mutagens that can cause mutations in humans.

36. Definitions Mutagens Environmental influences that cause mutations
Examples:
Radiaton: radioactive elements, ultraviolet (UV) light, X rays
Organic chemicals: cigarette smoke, pesticides

37. Any Questions?

38. Closing http://vcell.ndsu.nodak.edu/animations/transcription/movie.htm
A new film has been made – Lost in Translation
Part 1 =
Part 2 =