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DNADNA mRNA RNA ProteinProtein

Nuclearmembrane

TranscriptionTranscription

TranslationTranslation

DNA

mRNA

Ribosome

Protein

EukaryotEukaryotic Cellic Cell

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What is the name of What is the name of this pathway to this pathway to

making a protein?making a protein?DNADNA

mRNAmRNA

ProteinProtein

1. mRNA is transcribed from DNA

2. mRNA is translated into a protein

Transcription

Translation

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RNA RNA VocabulaVocabula

ryry

codon

Each group of three nitrogenous bases located on mRNA.

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ribosomal RNA (rRNA)

The two-part ribosome that reads mRNA

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amino acidCreate proteins when arranged in a chain.

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transfer RNA (tRNA)

Carries amino acids from the cytoplasm to the ribosome

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UA C

methionine

anticodonEach group of nitrogenous bases that complements a codon.

These groups of bases are located on tRNA.

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Making a Making a ProteinProtein

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Protein SynthesisProtein Synthesis The production (creation) of The production (creation) of

proteinsproteins Two phases:Two phases:

Transcription Transcription & & TranslationTranslation mRNA must be mRNA must be made before it made before it

leaves the nucleusleaves the nucleus of eukaryotic of eukaryotic cellscells

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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).

Let’s Make a Protein !Let’s Make a Protein !

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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

Kno-Gen Review

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1) Transcription

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2) Translation2) Translation

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

Example structure of a proteinExample structure of a protein

aa aa aa aa aa aa

peptide bonds

codon 2 codon 3 codon 4 codon 5 codon 6 codon 7codon 1

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A codon chart does not need to A codon chart does not need to be memorized.be memorized.