1. Proteins and Translation
DNA
RNA
PROTEIN

2. Proteins polymers made of many repeating amino acids
the type of and order of the amino acid pieces determines the protein’s structure (shape)
this order is determined by the code (instructions) in mRNA
the mRNA was copied from the DNA code (instructions) during transcription
the structure (shape) determines if the protein can perform its function (job)

3. Proteins proteins have many functions
EX: form most of our tissues and organs
EX: form enzymes that speed up chemical reactions
EX: form many types of hormones that send chemical messages in blood

4. RNA after Transcription
after mRNA is edited, it leaves the nucleus

5. RNA after Transcription
once it gets to the ribosome, it will help make a protein

6. Translation
decoding of an mRNA message into a chain of attached amino acids (protein)
cells use information from mRNA to produce a specific protein by linking amino acids together

7. Steps of Translation

8. TEM of a cell with stained ribosomes
translation occurs at specialized cell structures called ribosomes
cells can have millions of ribosomes to make all of the proteins we need
TEM of a cell with stained ribosomes

9. TEM of a cell with stained ribosomes
So what is a ribosome’s function?
Make proteins!
TEM of a cell with stained ribosomes

10. Proteins and Translation

11. Translation Animation
Steps of Translation
Translation Animation

12. The Genetic Code
ribosomes read the language of RNA in groups of 3 nitrogen bases
“triplets” of A, U, C, or G

13. mRNA
a type of RNA that is a copy of a gene’s instructions for how to make a protein

14. Codons a group of three bases on an mRNA strand
Start Codon (AUG) – signals the beginning of a protein chain
always brings the amino acid methionine

15. The Genetic Code

16. Codons a group of three bases on an mRNA strand
Start Codon (AUG) – signals the beginning of a protein chain
always brings the amino acid methionine
Stop Codons (UAA, UAG, or UGA) – signals for the end of protein synthesis
does not code for any amino acids

17. The Genetic Code

18. Steps of Translation

19. tRNA
a type of RNA that bonds to the mRNA and brings amino acids to the ribosome

20. Proteins and Translation

21. Steps of Translation

22. Anticodons a group of three bases on tRNA that bind to the mRNA codon
bind in a complementary fashion (A with U, C with G)
each piece of tRNA has only 1 type of anticodon and only 1 type of amino acid
because codons and anticodons have to bond complementary, when a codon enters a ribosome, the same amino acid will be added to the protein each time

23. Steps of Translation

24. Genetic Code Tables based on Codons from mRNA
use a mRNA Codon Table to determine the order of amino acids

25. Steps of Translation

26. Peptide Bond
a special type of covalent bond that holds two amino acids together
covalent bonds – electrons are shared between two amino acids

27. Steps of Translation

28. Polypeptide Chain
multiple peptide bonds holding together multiple amino acids
the beginning of a protein

29. Translation and Proteins
DNA
RNA
PROTEIN

30. Protein Synthesis Concept Map
transcription
translation
DNA
RNA
protein
(in the nucleus)
(at a ribosome)

31. Other Resources
See the diagrams and videos on the Unit 5.1 Links section of the class wiki

32. Summary
The parent DNA strand on the right has been transcribed into a single stranded piece of mRNA. Translate the mRNA sequence into a sequence of amino acids using the Genetic Code table. Remember, codons from mRNA get put into groups of three bases.

33. DNA Strands
mRNA Strand
Amino Acid Sequence A T U G C
Summary

34. The Genetic Code

35. Summary DNA Strands Amino Acid Sequence A T U Methionine G C
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Summary

36. The Genetic Code

37. Summary DNA Strands Amino Acid Sequence A T U Methionine G C Arginine
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Arginine
Summary

38. The Genetic Code

39. Summary DNA Strands Amino Acid Sequence A T U Methionine G C Arginine
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Arginine
Leucine
Summary

40. The Genetic Code

41. Summary DNA Strands Amino Acid Sequence A T U Methionine G C Arginine
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Arginine
Leucine
Threonine
Summary

42. The Genetic Code

43. Summary DNA Strands Amino Acid Sequence A T U Methionine G C Arginine
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Arginine
Leucine
Threonine
Histidine
Summary

44. The Genetic Code

45. Summary DNA Strands Amino Acid Sequence A T U Methionine G C Arginine
mRNA Strand
Amino Acid Sequence A T U
Methionine G C
Arginine
Leucine
Threonine
Histidine
Summary

46. A stop codon does not carry an amino acid. Don’t write “STOP”
A stop codon does not carry an amino acid! Don’t write “STOP”!!! There is not an amino acid called “STOP”.

47. Thought Question…
Can 1 piece of DNA be used to make many copies of the same protein?
To help answer this…
How is DNA involved in making a protein?
What happens to DNA after its “job” is completed in protein synthesis?
Can it be reused after its “job” is completed?

48. Thought Question… How is DNA involved in making a protein?
transcription
translation
RNA
DNA
protein

49. Thought Question…
What happens to DNA after its “job” is completed in protein synthesis?
Can it be reused after its “job” is completed?

50. TEM of a cell with stained ribosomes
Thought Question…
Eukaryotic cells can contain millions of ribosomes per cell.
TEM of a cell with stained ribosomes

51. Thought Question…
Can 1 piece of DNA be used to make many copies of the same protein?
RNA
protein
RNA
protein
DNA
RNA
protein
RNA
protein
RNA
protein

52. Thought Question…
Can 1 piece of DNA be used to make many copies of the same protein?
YES!!!
…because 1 piece of DNA can be used to make many pieces of RNA and each RNA piece can be used to make a protein

53. Steps of Translation

54. Steps of Translation