GENE

transcript

GENEEXPRESSION

Spark Starter

• Where does the mRNA travel to after it is synthesized in the nucleus?

• What molecule does the mRNA bind to at this site?

Today’s Task..

• Review Transcription • Translation• mRNA provides the code for Amino acids• Amino Acids are the building blocks of proteins

Video…

Transcription Recap…

1. RNA polymerase unwinds DNA

2. RNA polymerase adds RNA nucleotides

(A ↔ U, G ↔ C)

3. mRNA is formed! DNA reforms a double helix

Transcription recap…

• RNA polymerase makes mRNA using DNA sequence

• mRNA leaves the nucleus for the cytoplasm

TranslationTRANSLATION: process of “decoding” a strand of mRNA to create proteins

To Accomplish this the cell uses 2 special molecules: the Ribosome (rRNA) and the tRNA

RibosometRNA

Translation

• Ribosomes translate mRNA into an amino acid sequence

• Amino acids form proteins

To a ribosome!

Let’s Break It Down!

Translation—process of “decoding” a strand of mRNA to create proteins

Step 1: Reading the Codon

Step 2: Matching the Codon with the anticodon

Step 3: Elongation

Codons = 3 nucleotides in a row

2nd Ribosome reads the codon on mRNA

anticodon

amino acid

1st mRNA binds to the Ribosome

Codons = 3 nucleotides in a row

Box the Codon on your paper…

AUGACGGAGCUUCGGAGCUAGGAUUAC

CACAUGGAGGAUUACCUGCUAGCUAGU

ACGGGCUGCAUGAGCUUCGGGAGCUUC

Step 3: Elongation

The Anticodon is found on the tRNA (Transfer RNA)

Anticodon = 3 nucleotides on one end of a tRNA

Anticodons base pair with complementary bases on mRNA

anticodon

amino acid

Step 2: Matching the codon w/t the anticodon

Ribosome reads the codon and matches it with its complementary 3 base sequence called the Anticodon

anticodon

amino acid

Transfer RNA (tRNA)

Carries a unique amino acid that corresponds with its Anticodon

Each tRNA with a different anticodon will carry a different amino acids

Create the Anticodon to the following codon

AUGACGGAGCUUCGGAGCUAGGAUUACUACUGCCUCGAAGCCUCGAUCCUAAUG

CACAUGGAGGAUUACCUGCUAGCUAGUGUGUACCUCCUAAUGGACGAUCGAUCA

ACGGGCUGCAUGAGCUUCGGGAGCUUCUGCCCGACGUACUCGAAGCCCUCGAAG

Step 3: Elongation

anticodon

amino acid

Step 3: Elongation

Transfer RNA (tRNA)

The tRNA with its amino acid binds to the ribosome

The ribosome then starts connecting amino acids together to form a protein

Codon triplets code for 1 of 20 amino acids

Step 3: Elongation

Genetics Code Chart

Step 3: Elongation

Match the Codon with its corresponding amino acid using the Genetics Code chart

1 “start” codon 3 “stop” codonsCodons

Steps of Translation

1. mRNA attaches to ribosome

2. tRNAs add amino acids based on how anticodons match to mRNA

3. Protein is released from ribosomes!

Protein chain

Stop codon

Protein chain

3. Protein is released from ribosomes!

Summary

PROTEIN

(Transcription)

(Translation)

Practice1.DNA sequence: AAC TGA CTG ATT GCA TGC• What is the complementary DNA sequence?• What is the complementary RNA sequence?

2.DNA sequence: TAG CAT TGG GCA TCA CGA• What is the complementary DNA sequence?• What is the complementary RNA sequence?

TTG ACT GAC TAA CGT ACG

UUG ACU GAC UAA CGU ACG

ATC GTA ACC CGT AGT GCT

AUC GUA ACC CGU AGU GCU

Determine the amino acids for this strand of mRNA:AUG GCA AGU UCU UGA

Practice

Met – Ala – Ser – Ser – STOP

Determine the amino acids for this strand of mRNA:UGU AGA GAU CUC UAA

Practice

Cys – Arg – Asp – Leu – STOP

GENE

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