rna and protein synthesis
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How your cell makes very How your cell makes very important proteinsimportant proteins
• The production (synthesis) of proteinsproteins.
• 3 phases3 phases:
1.1. TranscriptionTranscription
2.2. RNA processingRNA processing
3.3. TranslationTranslation
• DNA DNA RNA RNA ProteinProtein
DNA DNA RNA RNA ProteinProtein
Nuclearmembrane
TranscriptionTranscription
RNA ProcessingRNA Processing
TranslationTranslation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Eukaryotic CellCell
Before making proteins, Your Before making proteins, Your cell must first make RNAcell must first make RNA
• Question:Question:
• How does RNARNA (ribonucleic acid) (ribonucleic acid) differ from DNA (deoxyribonucleic acid)DNA (deoxyribonucleic acid)?
RNARNA differs from DNADNA
1. RNARNA has a sugar ribosesugar ribose
DNADNA has a sugar deoxyribosesugar deoxyribose
2. RNARNA contains uracil (U)uracil (U)
DNADNA has thymine (T)thymine (T)
3. RNARNA molecule is single-strandedsingle-stranded
DNADNA is double-strandeddouble-stranded
1. Transcription1. Transcription
• Then moves along one of the DNA strandsDNA strands and links RNARNA nucleotides together.
Nuclearmembrane
TranscriptionTranscription
RNA ProcessingRNA Processing
TranslationTranslation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Eukaryotic CellCell
1. Transcription OR1. Transcription OR RNA production RNA production
• RNA molecules are produced by copying part of DNA into a complementary sequence of RNA
• This process is started and controlled by an enzyme called RNA polymerase.
Question:Question:
• What would be the complementary RNARNA strand for the following DNADNA sequence?
• DNA 5’-GCGTATG-3’DNA 5’-GCGTATG-3’
Types of RNATypes of RNA
• Three types ofThree types of RNARNA:
A.A. messenger RNA (mRNA)messenger RNA (mRNA)
B.B. transfer RNA (tRNA)transfer RNA (tRNA)
C.C. ribosome RNA (rRNA)ribosome RNA (rRNA)
• Remember: all produced in theRemember: all produced in the nucleusnucleus!!
mRNA
• Carries instructions from DNA to the rest of the ribosome.
• Tells the ribosome what kind of protein to make
• Acts like an email from the principal to the cafeteria lady.
A. Messenger RNA (mRNA)A. Messenger RNA (mRNA)
methionine glycine serine isoleucine glycine alanine stopcodon
proteinprotein
A U G G G C U C C A U C G G C G C A U A AmRNAmRNA
startcodon
Primary structure of a proteinPrimary structure of a protein
aa1 aa2 aa3 aa4 aa5 aa6
peptide bonds
codon 2 codon 3 codon 4 codon 5 codon 6 codon 7codon 1
If the cell is a school…If the cell is a school…
• The Nucleus is the school officeThe Nucleus is the school office• The Nucleolus is the principal’s The Nucleolus is the principal’s
officeoffice• The DNA is the principalThe DNA is the principal• Ribosomes are the cafeteria ladiesRibosomes are the cafeteria ladies• mRNA is the email from the mRNA is the email from the
principal to the cafeteria ladyprincipal to the cafeteria lady
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
rRNA
• Part of the structure of a ribosome
• Helps in protein production
tRNA
A go-getter. Gets the right parts to make the right protein according to mRNA instructions
B. Transfer RNA (tRNA)B. Transfer RNA (tRNA)
amino acidamino acidattachment siteattachment site
U A C
anticodonanticodon
methionine amino acidamino acid
2. RNA Processing2. RNA Processing
Nuclearmembrane
TranscriptionTranscription
RNA ProcessingRNA Processing
TranslationTranslation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Eukaryotic CellCell
2. RNA Processing2. RNA Processing
• IntronsIntrons are pulled out and exonsexons come together.
• End product is a mature RNA mature RNA moleculemolecule that leaves the nucleusnucleus to the cytoplasm.cytoplasm.
• Introns bad…… Exons good!Introns bad…… Exons good!
2. RNA Processing2. RNA Processing
pre-RNA molecule
intron
intronexon exon exon
exon exon exon
Mature RNA moleculeMature RNA molecule
exon exon exon
intron intron
splicesome splicesome
3. Translation - making 3. Translation - making proteinsproteins
Nuclearmembrane
TranscriptionTranscription
RNA ProcessingRNA Processing
TranslationTranslation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Eukaryotic CellCell
3. Translation3. Translation
• Three parts:
1. initiationinitiation: start codon (AUG)
2. elongationelongation:
3. terminationtermination: stop codon (UAG)
• Let’s make a PROTEIN!!!!PROTEIN!!!!.
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
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
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)
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
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
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
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
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
End ProductEnd Product• The end products of protein synthesis is
a primary structure of a proteinprimary structure of a protein.
• A sequence of amino acid amino acid bonded together by peptide bondspeptide bonds.
aa1
aa2 aa3 aa4aa5
aa200
aa199
Question:Question:
• The anticodon The anticodon UACUAC belongs to a belongs to a tRNAtRNA that that recognizes and binds to a particular recognizes and binds to a particular amino amino acidacid..
• What would be the What would be the DNA base code DNA base code for this for this amino acid?amino acid?
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