2009-2010

Protein Synthesis Making Proteins

Bodies are made up of cells All cells run on a set of instructions spelled

out in DNA

Bodies Cells DNA

How does DNA code for cells & bodies? how are cells and bodies made from the

instructions in DNA

DNA Cells Bodies

DNA has the information to build proteins genes

DNA Proteins Cells Bodies

proteinscells

bodiesDNA gets all the glory,Proteins do all the work

How do proteins do all the work• Proteins– proteins run living organisms– enzymes• control all chemical reactions in living organisms

– structure• all living organisms are built out of proteins

cytoplasm

nucleus

Cell organization• DNA– DNA is in the nucleus• genes = instructions for making proteins

– want to keep it there = protected• “locked in the vault”

Cell organization• Proteins– chains of amino acids– made by a “protein factory” in cytoplasm– protein factory = ribosome

nucleus

cytoplasm

ribosome

aa

aa

aa

aa

aa

aa

aa

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aa

buildproteins

Passing on DNA information• Need to get DNA gene information

from nucleus to cytoplasm– need a copy of DNA– messenger RNA

nucleus

cytoplasm

ribosome

mRNA

buildproteins

aa

aa

aa

aa

aa

aa

aa

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aa

mRNA

From nucleus to cytoplasm

DNAtranscription

nucleuscytoplasm

translation

trait

aa

aa

aa

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aa

protein

DNA vs. RNADNA

• deoxyribose sugar • nitrogen bases– G, C, A, T– T : A– C : G

• double stranded

RNA• ribose sugar • nitrogen bases– G, C, A, U– U : A– C : G

• single stranded

Transcription

• Making mRNA from DNA• DNA strand is the

template (pattern)– match bases• U : A• G : C

• Enzyme– RNA polymerase

Matching bases of DNA & RNA• Double stranded DNA unzips

A G GGGGGT T A C A C T T T T TC C C CA A

Matching bases of DNA & RNA• Double stranded DNA unzips

A G GGGGGT T A C A C T T T T TC C C CA A

Matching bases of DNA & RNA• Match RNA bases to DNA

bases on one of the DNA strands

U

A G GGGGGT T A C A C T T T T TC C C CA A

U

UU

U

U

G

G

A

A

A C CRNA polymerase

C

C

C

C

C

G

GG

G

A

A

A

AA

Matching bases of DNA & RNA• U instead of T is matched to A

TACGCACATTTACGTACGCGGDNA

AUGCGUGUAAAUGCAUGCGCCmRNAaa

aa

aa

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aa

U C CCCCCA A U G U G A A A A AG G G GU Uribosome

aa

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protein

cytoplasm

nucleus

traitU C CCCCCA A U G U G A A A A AG G G GU U

ribosome

How does mRNA code for proteins• mRNA leaves nucleus• mRNA goes to ribosomes in cytoplasm• Proteins built from instructions on mRNA

aa aa aa aa aa aa aa aa

How?

mRNAU C CCCCCA A U G U G A A A A AG G G GU U

How does mRNA code for proteins?TACGCACATTTACGTACGCGGDNA

AUGCGUGUAAAUGCAUGCGCCmRNA

Met Arg Val Asn Ala Cys Alaprotein?

How can you code for 20 amino acids withonly 4 DNA bases (A,U,G,C)?

ribosome

aa aa aa aa aa aa aa aa

AUGCGUGUAAAUGCAUGCGCCmRNA

mRNA codes for proteins in tripletsTACGCACATTTACGTACGCGGDNA

AUGCGUGUAAAUGCAUGCGCCmRNA

Met Arg Val Asn Ala Cys Alaprotein

?

Codon = block of 3 mRNA bases

codon

ribosome

• For ALL life!– strongest support for a

common origin for all life

• Code has duplicates– several codons for each

amino acid– mutation insurance!

Start codon AUG methionine

Stop codons UGA, UAA, UAG

The mRNA code

How are the codons matched to amino acids?

TACGCACATTTACGTACGCGGDNA

AUGCGUGUAAAUGCAUGCGCCmRNA

anti-codon

codon

tRNAUAC

MetGCA

ArgCAU

Val Anti-codon = block of 3 tRNA bases

aminoacid

mRNA to protein = Translation• The working instructions mRNA• The reader ribosome• The transporter transfer RNA (tRNA)

mRNAU C CCCCCA A U G U G A A A A AG G G GU U

aaaa

aa

tRNA

GGU

aatRNA

U A C

aatRNA

GA C

tRNA

aa

A GU

ribosome

aa

aa

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aa

aa

aa

mRNA

From gene to protein

DNAtranscription

nucleus cytoplasm

proteintranslation

trait

U C CCCCCA A U G U G A A A A AG G G GU Uribosome

tRNAaa

protein

aa

aa

aa

aa

aa

aa

aa

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aa

transcription

cytoplasm

nucleus

translation

trait

From gene to protein

transcription

translation

protein

2009-2010

Whoops!See what happens when your genes don’t work right!Any Questions??