protein synthesis
DESCRIPTION
PROTEIN SYNTHESIS. 3 Types of RNA. mRNA= messenger tRNA= transfer rRNA= ribosomal. The Central Dogma. DNA The master program of the cell Never leaves the nucleus Transcription Process that makes mRNA from DNA Takes place in the nucleus Translation Process that makes proteins from mRNA - PowerPoint PPT PresentationTRANSCRIPT
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PROTEIN PROTEIN SYNTHESISSYNTHESIS
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3 Types of RNA• mRNA= messenger• tRNA= transfer• rRNA= ribosomal
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The Central Dogma• DNA
– The master program of the cell
– Never leaves the nucleus
• Transcription– Process that makes mRNA
from DNA– Takes place in the nucleus
• Translation– Process that makes proteins
from mRNA– Takes place in the cytoplasm
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Steps in Steps in TranscriptionTranscription
InitiationInitiation ElongationElongation TerminationTermination
When complete, When complete, pre-RNApre-RNA molecule is releasedmolecule is released
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TranscriptionTranscription
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Question:Question:
What would be the What would be the complementary RNA complementary RNA strand for the following strand for the following DNA sequence?DNA sequence?
DNA 5’-DNA 5’-GCGTATGGCGTATG-3’-3’
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RNA ProcessingRNA Processing
pre-RNA molecule
intron
intronexon exon exon
exon exon exon
Mature RNA moleculeMature RNA molecule
exon exon exon
intron intron
splicesome splicesome
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TranslationTranslation
•Synthesis of proteinsSynthesis of proteins in the in the cytoplasmcytoplasm
• Involves the following:Involves the following:
1.1. mRNA (codons)mRNA (codons)
2.2. tRNA (anticodons)tRNA (anticodons)
3.3. ribosomesribosomes
4.4. amino acidsamino acids
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TranslationTranslation• Three steps:Three steps:
1.1. initiationinitiation: start codon (AUG): start codon (AUG)
2.2. elongationelongation: amino acids : amino acids linkedlinked
3.3. terminationtermination: stop codon : stop codon (UAG, UAA, or UGA).(UAG, UAA, or UGA).
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mRNA Codons Join the mRNA Codons Join the RibosomeRibosome
PSite
ASite
Largesubunit
Small subunit
mRNAmRNA
A U G C U A C U U C G
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InitiationInitiation
mRNAmRNA
A U G C U A C U U C G
2-tRNA
G
aa2
A U
A
1-tRNA
U A C
aa1
anticodon
hydrogenbonds codon
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mRNAmRNA
A U G C U A C U U C G
1-tRNA 2-tRNA
U A C G
aa1 aa2
A UA
anticodon
hydrogenbonds codon
peptide bond
3-tRNA
G A A
aa3
ElongationElongation
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mRNAmRNA
A U G C U A C U U C G
1-tRNA
2-tRNA
U A C
G
aa1
aa2
A UA
peptide bond
3-tRNA
G A A
aa3
Ribosomes move over one codon
(leaves)
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mRNAmRNA
A U G C U A C U U C G
2-tRNA
G
aa1
aa2
A UA
peptide bonds
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
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mRNAmRNA
A U G C U A C U U C G
2-tRNA
G
aa1aa2
A U
A
peptide bonds
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
(leaves)
Ribosomes move over one codon
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mRNAmRNA
G C U A C U U C G
aa1aa2
A
peptide bonds
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
U G A
5-tRNA
aa5
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mRNAmRNA
G C U A C U U C G
aa1aa2
A
peptide bonds
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
U G A
5-tRNA
aa5
Ribosomes move over one codon
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mRNAmRNA
A C A U G U
aa1
aa2
U
primaryprimarystructurestructureof a proteinof a protein
aa3
200-tRNA
aa4
U A G
aa5
C U
aa200
aa199
terminatorterminator or stopor stop codoncodon
TerminationTermination
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End Product –The End Product –The Protein!Protein!
• The end products of protein The end products of protein synthesis is a synthesis is a primary structureprimary structure of a proteinof a protein
• A A sequence of amino acidsequence of amino acid bonded together by peptide bonded together by peptide bondsbonds
aa1
aa2 aa3 aa4aa5
aa200
aa199
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Question:Question:
What would be the Amino What would be the Amino acid sequence for the acid sequence for the following mRNA strand?following mRNA strand?
mRNA mRNA CGAUGUUCAGACGCGGGUACGAUGUUCAGACGCGGGUA
ACGACG
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