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PROTEIN PROTEIN SYNTHESIS SYNTHESIS 1

PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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Page 1: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

PROTEIN PROTEIN SYNTHESISSYNTHESIS

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Page 2: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

DNA AND DNA AND GENESGENES

Page 3: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

DNADNA

■DNA contains genes, sequences of nucleotide bases

■Genes have different alleles.

■These genes code for polypeptides (proteins)

Page 4: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Genes & ProteinsGenes & Proteins

Proteins are made of amino acids linked together by covalent bonds called peptide bonds

Dehydration synthesis or condensation reactions form the bonds

20 different amino acids exist

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Page 5: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Amino Acid StructureAmino Acid Structure

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Page 6: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

PolypeptidesPolypeptides

■Amino acid chains are called polypeptides

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Page 7: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

DNA Begins the DNA Begins the ProcessProcess

■DNA is found inside the nucleus

■Proteins, however, are made in the cytosol of cells by organelles called ribosomes

■Ribosomes may be free in the cytosol or attached to the surface of rough ER

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Page 8: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Starting with DNAStarting with DNA

■DNA ‘s codeDNA ‘s code must be must be copiedcopied and taken to the cytosoland taken to the cytosol

■In the cytosol, this In the cytosol, this code code must be readmust be read so so amino acidsamino acids can be assembled to make can be assembled to make polypeptides (proteins)polypeptides (proteins)

■This process is called This process is called PROTEIN SYNTHESISPROTEIN SYNTHESIS

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Page 9: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

RNARNA

Page 10: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Roles of RNA and DNA

■DNA is the MASTER PLAN

■RNA is the copy of the Master Plan

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Page 11: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

RNA Differs from DNARNA Differs from DNA

■ RNA has a sugar RNA has a sugar riboseribose

DNA has a sugar DNA has a sugar deoxyribosedeoxyribose

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Page 12: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Other DifferencesOther Differences

■ RNA contains the base RNA contains the base uracil (Uuracil (U))

DNA has DNA has thymine (T)thymine (T)

■ RNA molecule is RNA molecule is single-single-strandedstranded

DNA is DNA is double-strandeddouble-stranded

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DNA

Page 13: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Structure of RNAStructure of RNA

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Page 14: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Three Types of RNAThree Types of RNA

■Messenger RNA (mRNA)Messenger RNA (mRNA) copies copies DNA’s code & carries the genetic DNA’s code & carries the genetic information to the ribosomesinformation to the ribosomes

■Ribosomal RNA (rRNA)Ribosomal RNA (rRNA), along with , along with protein, makes up the ribosomesprotein, makes up the ribosomes

■Transfer RNA (tRNA)Transfer RNA (tRNA) transfers transfers amino acids to the ribosomes amino acids to the ribosomes where proteins are synthesizedwhere proteins are synthesized

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.

Page 15: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Messenger RNA

■Long Straight chain of Nucleotides

■Made in the Nucleus■Copies DNA & leaves

through nuclear pores■Contains the Nitrogen

Bases A, G, C, U ( no T )

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Page 16: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Messenger RNA (mRNA)Messenger RNA (mRNA)

■Carries the information for a Carries the information for a specific proteinspecific protein

■Made up of Made up of 500 to 1000 500 to 1000 nucleotides longnucleotides long

■Sequence of 3 bases called Sequence of 3 bases called codoncodon

■AUGAUG – methionine or – methionine or start codonstart codon

■UAA, UAG, or UGAUAA, UAG, or UGA – – stop codonsstop codons

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Page 17: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Ribosomal RNA (rRNA)Ribosomal RNA (rRNA)

■rRNA is a single strand rRNA is a single strand 100 to 3000 nucleotides100 to 3000 nucleotides longlong

■GlobularGlobular in shape in shape■Made inside the Made inside the nucleusnucleus

of a cell in the nucleolusof a cell in the nucleolus■Associates with Associates with

proteins to form proteins to form ribosomesribosomes

■Site of Site of protein protein SynthesisSynthesis

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Page 18: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Transfer RNA (tRNA)Transfer RNA (tRNA)

■Clover-leaf shape■Single stranded molecule

with attachment site at one end for an amino acid

■Opposite end has three nucleotide bases called the anticodon

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Page 19: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Transfer RNATransfer RNA

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amino acidamino acidattachment siteattachment site

U A C

anticodonanticodon

Page 20: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Codons and Anticodons

■The 3 bases of an anticodon are complementary to the 3 bases of a codon

■Example: Codon ACU

Anticodon UGA

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UGA

ACU

Page 21: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

The Genetic Code

■A codon designates an amino acid

■An amino acid may have more than one codon

■There are 20 amino acids, but 64 possible codons

■Some codons tell the ribosome to stop translating

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Page 22: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

The Genetic Code

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•Use the code by reading from the center to the outside•Example: AUG codes for Methionine

Page 23: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Name the Amino Acids

■GGG?■UCA?■CAU?■GCA?■AAA?

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Page 24: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

TRANSCRIPTION TRANSCRIPTION AND AND

TRANSLATIONTRANSLATION

Page 25: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Pathway to Making a Pathway to Making a ProteinProtein

DNADNA

mRNAmRNA

tRNA (ribosomes)tRNA (ribosomes)

ProteinProtein

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Page 26: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Protein SynthesisProtein Synthesis

The production or synthesis of polypeptide chains (proteins)

Two phases: Transcription & Translation

mRNA must be processed before it leaves the nucleus of eukaryotic cells

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Page 27: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

DNADNA RNARNA ProteinProtein

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Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

EukaryotEukaryotic Cellic Cell

Page 28: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

TranscriptionTranscription

■The process of copying the sequence of one strand of DNA, the template strand

■mRNA copies the template strand

■Requires the enzyme RNA Polymerase

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Page 29: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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Page 30: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Answer:Answer:

■DNA 5’-GCGTATG-DNA 5’-GCGTATG-3’3’

■RNA 3’-CGCAUAC-RNA 3’-CGCAUAC-5’5’

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Page 31: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

TranscriptionTranscription

■During transcription, RNA polymerase binds to DNA and separates the DNA strands

■RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA

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Page 32: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

TranscriptionTranscription

■Promoters are regions on DNA that show where RNA Polymerase must bind to begin the Transcription of RNA

■Called the TATA box■Specific base sequences act as

signals to stop■Called the termination signal

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Page 33: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

RNA PolymeraseRNA Polymerase

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Page 34: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

mRNA ProcessingmRNA Processing

■After the DNA is transcribed into RNA, editing must be done to the nucleotide chain to make the RNA functional

■Introns, non-functional segments of DNA are snipped out of the chain

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Page 35: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

mRNA EditingmRNA Editing■Exons, segments of RNA that

code for proteins, are then rejoined by the enzyme ligase

■A guanine triphosphate cap is added to the 5” end of the newly copied mRNA

■A poly A tail is added to the 3’ end of the RNA

■The newly processed mRNA can then leave the nucleus

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Page 36: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

36CAP

TailNew Transcript

Result of TranscriptionResult of Transcription

Page 37: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

mRNA Transcript

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•mRNA leaves the nucleus through its pores and goes to the ribosomes

Page 38: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

TranslationTranslation

■Translation is the process of of decoding the mRNA into a polypeptide chain

■Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins

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Page 39: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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TranscriptioTranscriptionn

TranslatiTranslationon

Page 40: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

RibosomesRibosomes

■Made of a large and small subunit

■Composed of rRNA (40%) and proteins (60%)

■Have two sites for tRNA attachment --- P and A

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Page 41: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Step 1- InitiationStep 1- Initiation

■mRNA transcript start codon AUG attaches to the small ribosomal subunit

■Small subunit attaches to large ribosomal subunit

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mRNA transcript

Page 42: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

RibosomesRibosomes

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PSite

ASite

Largesubunit

Small subunit

mRNAmRNA

A U G C U A C U U C G

Page 43: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Step 2 - Elongation■As ribosome moves, two

tRNA with their amino acids move into site A and P of the ribosome

■Peptide bonds join the amino acids

Page 44: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

InitiationInitiation

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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

Page 45: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 46: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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)

Page 47: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 48: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 49: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 50: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 51: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

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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

Page 52: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

End Product –The Protein!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

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aa1

aa2 aa3 aa4aa5

aa200

aa199

Page 53: PROTEIN SYNTHESIS 1. DNA AND GENES DNA ■ DNA contains genes, sequences of nucleotide bases ■ Genes have different alleles. ■ These genes code for polypeptides

Messenger RNA Messenger RNA (mRNA)(mRNA)

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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