rna and protein synthesis

RNA ANDRNA AND PROTEIN PROTEIN

SYNTHESISSYNTHESIS

By By Muhammad AsifMuhammad AsifPu PakPu Pak

Muhammad Asif PuMuhammad Asif Pu

How your cell makes very important How your cell makes very important proteinsproteins

The production (synthesis) of proteinsproteins.3 phases3 phases:

1.1. TranscriptionTranscription

2.2. RNA processingRNA processing

3.3. TranslationTranslation

DNA DNA RNA RNA ProteinProtein

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DNA DNA RNA RNA ProteinProtein

Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

Eukaryotic Eukaryotic CellCell

Muhammad Asif PuMuhammad Asif Pu

Before making proteins, Your cell Before making proteins, Your cell must first make RNAmust first make RNA

Question:Question:How does RNARNA (ribonucleic acid) (ribonucleic acid) differ

from DNA (deoxyribonucleic acid)DNA (deoxyribonucleic acid)?

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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

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Muhammad Asif PuMuhammad Asif Pu

1. Transcription1. Transcription

Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

Eukaryotic Eukaryotic CellCell

Muhammad Asif PuMuhammad Asif Pu

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.

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1. Transcription1. Transcription

DNADNA

pre-mRNApre-mRNA

RNA PolymeraseRNA Polymerase

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Question:Question:

What would be the complementary RNARNA strand for the following DNADNA sequence?

DNA 5’-GCGTATG-3’DNA 5’-GCGTATG-3’

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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!!

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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.

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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

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If the cell is a school…If the cell is a school…

The Nucleus is the school officeThe Nucleus is the school officeThe Nucleolus is the principal’s The Nucleolus is the principal’s

officeofficeThe DNA is the principalThe DNA is the principalRibosomes are the cafeteria Ribosomes are the cafeteria

ladiesladiesmRNA is the email from the mRNA is the email from the

principal to the cafeteria ladyprincipal to the cafeteria ladyMuhammad Asif PuMuhammad Asif Pu

rRNA

Part of the structure of a ribosomeHelps in protein production

tRNA

A go-getter. Gets the right parts to make the right protein according to mRNA instructions

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B. Transfer RNA (tRNA)B. Transfer RNA (tRNA)

amino acidamino acidattachment siteattachment site

U A C

anticodonanticodon

methionine amino acidamino acid

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2. RNA Processing2. RNA Processing

Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

Eukaryotic Eukaryotic CellCell

Muhammad Asif PuMuhammad Asif Pu

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!

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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

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RibosomesRibosomes

PSite

ASite

Largesubunit

Small subunit

mRNAmRNA

A U G C U A C U U C G

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3. Translation - making proteins3. Translation - making proteins

Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

Eukaryotic Eukaryotic CellCell

Muhammad Asif PuMuhammad Asif Pu

3. Translation3. Translation

Three parts:1. initiationinitiation: start codon (AUG)2. elongationelongation:3. terminationtermination: stop codon (UAG)

Let’s make a PROTEIN!!!!PROTEIN!!!!.

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3. Translation3. Translation

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 codonMuhammad Asif PuMuhammad Asif Pu

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 codonMuhammad Asif PuMuhammad Asif Pu

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 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

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Question:Question:

The anticodon The anticodon UACUAC belongs to a belongs to a tRNAtRNA that recognizes and binds to a that recognizes and binds to a particular particular amino acidamino acid..

What would be the What would be the DNA base code DNA base code for for this this amino acid?amino acid?

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Answer:Answer:

tRNA tRNA - UAC - UAC (anticodon)(anticodon)

mRNAmRNA - AUG (codon)- AUG (codon)DNA DNA - TAC- TAC

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