1. PROTEIN SYNTHESIS

2. Protein Synthesis
The production (synthesis) of polypeptide chains (proteins)
Two phases: Transcription & Translation

3. SCI.9-12.B [Indicator] - Explain how DNA functions as the code of life and the blueprint for proteins.
SCI.9-12.B [Indicator] - Summarize the basic processes involved in protein synthesis (including transcription and translation).
H.B.4B.1 Develop and use models to describe how the structure of DNA determines the structure of resulting proteins or RNA molecules that carry out the essential functions of life.

4. Transcription – mRNA copying DNA, happens in the nucleus and mRNA must be edited or processed before it leaves the nucleus
Translation – when mRNA goes to ribosome and tRNA brings the correct amino acids to the ribosome

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

6. Pathway to Making a Protein
DNA
mRNA
tRNA (ribosomes)
Protein

7. Nucleic Acids

8. RNA

9. SCI.9-12.B [Indicator] - Compare DNA and RNA in terms of structure, nucleotides, and base pairs.

10. How DNA and RNA are alike:
Both made of monomers called nucleotides.
Both had A, G and C bases

11. *RNA Differs from DNA DNA has a sugar deoxyribose
1. RNA has a sugar ribose
DNA has a sugar deoxyribose
2. RNA contains the base uracil (U)
DNA has thymine (T)
3. RNA molecule is single-stranded
DNA is double-stranded

12. .
*Three Types of RNA
Messenger RNA (mRNA) carries genetic information to 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

13. Making a Protein

14. *Genes & Proteins
Proteins are made of amino acids linked together by peptide bonds
20 different amino acids exist
Amino acids chains are called polypeptides
Segment of DNA that codes for the amino acid sequence in a protein are called genes

15. Two Parts of Protein Synthesis
Transcription makes an RNA molecule complementary to a portion of DNA
Translation occurs when the sequence of bases of mRNA DIRECTS the sequence of amino acids in a polypeptide

16. SCI.9-12.B [Indicator] - Explain how DNA functions as the code of life and the blueprint for proteins.
SCI.9-12.B [Indicator] - Summarize the basic processes involved in protein synthesis (including transcription and translation).
H.B.4B.1 Develop and use models to describe how the structure of DNA determines the structure of resulting proteins or RNA molecules that carry out the essential functions of life.

17. *Genetic Code DNA contains a triplet code
Every three bases on DNA stands for ONE amino acid
Each three-letter unit on mRNA is called a codon
Most amino acids have more than one codon!
There are 20 amino acids with a possible 64 different triplets
The code is nearly universal among living organisms
The fact that the genetic code is about universal in living things suggests that the code dates back to the first organisms on earth and that all living things are related.

18. Notice that in this chart, each of the codons (white rectangles) is composed of three letters representing the first base, second base, and third base. For example, find the rectangle where C for the first base and A for the second base intersect. You will see that U, C, A, or G can be the third base. CAU and CAC are codons for histidine; CAA and CAG are codons for glutamine.

21. *What is the enzyme responsible for the production of the mRNA molecule?

22. *RNA Polymerase Enzyme found in the nucleus
Separates the two DNA strands by breaking the hydrogen bonds between the bases
Then moves along one of the DNA strands and links RNA nucleotides together

23. Question:
What would be the complementary RNA strand for the following DNA sequence?
DNA 5’-GCGTATG-3’

24. Answer:
DNA 5’-GCGTATG-3’
RNA 3’-CGCAUAC-5’

25. *Processing Pre-mRNA Also occurs in the nucleus
Pre-mRNA made up of segments called introns & exons
Exons code for proteins, while introns do NOT!
Introns spliced out by splicesome-enzyme and exons re-join
End product is a mature RNA molecule that leaves the nucleus to the cytoplasm

26. *Messenger RNA (mRNA) Carries the information for a specific protein
Made up of 500 to 1000 nucleotides long
Sequence of 3 bases called codon
AUG – methionine or start codon
UAA, UAG, or UGA – stop codons

27. Messenger RNA (mRNA) Primary structure of a protein A U G C aa1 aa2
start
codon
codon 2
codon 3
codon 4
codon 5
codon 6
codon 7
codon 1
methionine
glycine
serine
isoleucine
alanine
stop
codon
protein
Primary structure of a protein
aa1
aa2
aa3
aa4
aa5
aa6
peptide bonds

28. Transfer RNA (tRNA) methionine amino acid attachment site amino acidU A C
anticodon
methionine
amino acid

29. SCI.9-12.B [Indicator] - Explain how DNA functions as the code of life and the blueprint for proteins.
SCI.9-12.B [Indicator] - Summarize the basic processes involved in protein synthesis (including transcription and translation).
H.B.4B.1 Develop and use models to describe how the structure of DNA determines the structure of resulting proteins or RNA molecules that carry out the essential functions of life.

30. *Ribosomes Made of a large and small subunit
Composed of rRNA (40%) and proteins (60%)
Have two sites for tRNA attachment --- P and A

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

32. *Translation Let’s Make a Protein ! Three steps:
1. initiation: start codon (AUG)
2. elongation: amino acids linked
3. termination: stop codon (UAG, UAA, or UGA).
Let’s Make a Protein !

33. http://highered. mcgraw-hill. com/olcweb/cgi/pluginpop. cgi

35. mRNA Codons Join the Ribosome
Large
subunit P
Site A
Site
mRNA A U G C
Small subunit

36. Initiation G aa2 A U U A C aa1 A U G C U A C U U C G A codon 2-tRNA
anticodon A U G C U A C U U C G A
hydrogen
bonds
codon
mRNA

37. Elongation G A aa3 peptide bond aa1 aa2 U A C G A U A U G C U A C U U
3-tRNA G A
aa3
peptide bond
aa1
aa2
1-tRNA
2-tRNA
anticodon U A C G A U A U G C U A C U U C G A
hydrogen
bonds
codon
mRNA

38. Ribosomes move over one codon
aa1
peptide bond
3-tRNA G A
aa3
aa2
1-tRNA U A C
(leaves)
2-tRNA G A U A U G C U A C U U C G A
mRNA
Ribosomes move over one codon

39. peptide bonds G C U aa4 aa1 aa2 aa3 G A U G A A A U G C U A C U U C G
4-tRNA G C U
aa4
aa1
aa2
aa3
2-tRNA
3-tRNA G A U G A A A U G C U A C U U C G A A C U
mRNA

40. Ribosomes move over one codon
peptide bonds
4-tRNA G C U
aa4
aa1
aa2
aa3
2-tRNA G A U
(leaves)
3-tRNA G A A A U G C U A C U U C G A A C U
mRNA
Ribosomes move over one codon

41. peptide bonds U G A aa5 aa1 aa2 aa4 aa3 G A A G C U G C U A C U U C G
5-tRNA
aa5
aa1
aa2
aa4
aa3
3-tRNA
4-tRNA G A A G C U G C U A C U U C G A A C U
mRNA

42. Ribosomes move over one codon
peptide bonds U G A
5-tRNA
aa5
aa1
aa2
aa3
aa4
3-tRNA G A A
4-tRNA G C U G C U A C U U C G A A C U
mRNA
Ribosomes move over one codon

43. Termination aa5 aa4 aa3 primary structure of a protein aa2 aa1 A C U C
terminator
or stop
codon
200-tRNA A C U C A U G U U U A G
mRNA

44. *End Product –The Protein!
The end products of protein synthesis is a primary structure of a protein
A sequence of amino acid bonded together by peptide bonds
aa1
aa2
aa3
aa4
aa5
aa200
aa199

45. http://scetv. pbslearningmedia. org/resource/tdc02. sci. life. gen

46. SCI.9-12.B [Indicator] - Explain how DNA functions as the code of life and the blueprint for proteins.
SCI.9-12.B [Indicator] - Summarize the basic processes involved in protein synthesis (including transcription and translation).
H.B.4B.1 Develop and use models to describe how the structure of DNA determines the structure of resulting proteins or RNA molecules that carry out the essential functions of life.

47. *Types of Mutations
Point mutation – one DNA bases changes. Sometimes this mistake is corrected by an enzyme.
Types:
a. insertion – where a base is added
b. deletion – where a base is lost
c. substitution – where a base is changed

48. Base-pair substitution
Wild type A U G C
mRNA 5
Protein
Met
Lys
Phe
Gly
Stop
Carboxyl end
Amino end 3
Base-pair substitution
No effect on amino acid sequence
U instead of C
Ser
Missense
A instead of G
Nonsense
U instead of A

49. *The change of a single nucleotide in the DNA’s template strand
Leads to the production of an abnormal protein
In the DNA, the
mutant template
strand has an A where
the wild-type template
has a T.
The mutant mRNA has
a U instead of an A in
one codon.
The mutant (sickle-cell)
hemoglobin has a valine
(Val) instead of a glutamic
acid (Glu).
Mutant hemoglobin DNA
Wild-type hemoglobin DNA
mRNA
Normal hemoglobin
Sickle-cell hemoglobin
Glu
Val C T A G U 3 5
Figure 17.23

51. http://www. texomashomepage

52. *
2. Frameshift mutation – insertion or deletion of a nucleotide (or base) changes the group of three bases that code for the amino acid
ACT CAT TAG GAG (first T is deleted)
ACC ATT AGG AG

53. Base-pair insertion or deletion
mRNA
Protein
Wild type A U G C 5
Met
Lys
Phe
Gly
Amino end
Carboxyl end
Stop
Base-pair insertion or deletion
Frameshift causing immediate nonsense
Leu
Ala
Missing
Extra U
Frameshift causing
extensive missense
Insertion or deletion of 3 nucleotides:
no frameshift but extra or missing amino acid 3