Protein SynthesisProtein Synthesis

Review!Review!

What are some functions of proteins?What are some functions of proteins?EnzymesEnzymes, which speed up , which speed up chemical reactionschemical reactionsBuildBuild and repair cell structures and repair cell structuresDetermine the Determine the structure & functionstructure & function of living of living

organismsorganisms

Review!Review!Proteins are Proteins are polymerspolymers, made up of , made up of

monomers called monomers called amino acidsamino acidsThere are There are 20 20 different types of different types of amino acidsamino acids

Review!Review!What codes for these proteins?What codes for these proteins?DNADNA contains the sequence of contains the sequence of nucleotidesnucleotides

that codes for the synthesis of proteins. that codes for the synthesis of proteins. Problem:Problem:

DNA DNA is found in the is found in the nucleus.nucleus.Proteins are made at the Proteins are made at the ribosomesribosomes, which , which

are found in the cytoplasmare found in the cytoplasm

HOW CAN THE INFORMATION FROM HOW CAN THE INFORMATION FROM THE THE NUCLEUSNUCLEUS GET TO THE GET TO THE RIBOSOMERIBOSOME??RNA! – mRNARNA! – mRNA is used to move information is used to move information

from the DNA to ribosomes from the DNA to ribosomes This process is called This process is called TRANSCRIPTIONTRANSCRIPTION..

TranslationTranslation The process of The process of

converting the converting the informationinformation in the in the nitrogen base nitrogen base sequence of sequence of mRNA into a mRNA into a sequence of sequence of amino amino acidsacids which make which make up proteinsup proteins

Occurs in the Occurs in the RIBOSOMESRIBOSOMES

TranslationTranslation

1. mRNA 1. mRNA attachesattaches and passes through and passes through the the ribosome.ribosome.

2. First 2. First codoncodon on on mRNA moves into mRNA moves into position.position.

3. 3. tRNA tRNA (transfer (transfer RNA) starts to bring RNA) starts to bring amino acids amino acids to the to the ribosome.ribosome.

TranslationTranslation

4. tRNA 4. tRNA ANTICODONANTICODON matches up to matches up to mRNA mRNA codon.codon.

5. mRNA slides 5. mRNA slides through the through the ribosome to next ribosome to next mRNA codon.mRNA codon.

TranslationTranslation

6. New tRNA 6. New tRNA anticodon matches to anticodon matches to next mRNA codon.next mRNA codon.

7. Amino acids on two 7. Amino acids on two tRNAs form a tRNAs form a peptide peptide bond bond with one with one another. First tRNA another. First tRNA floats away floats away to pick up to pick up another another amino acid amino acid for later usefor later use

TranslationTranslation 8. Process continues 8. Process continues

until a until a stop codon stop codon on on the mRNA is reached.the mRNA is reached.

9. Result = 9. Result = an amino an amino acid chain acid chain is createdis created

*Chain of amino acids = *Chain of amino acids = polypeptide chain = polypeptide chain = PROTEIN (more than PROTEIN (more than one polypeptide chain)one polypeptide chain)

Protein Synthesis Animation

Let’s Review…again!Let’s Review…again!

Decode the followingDecode the following If the coding DNA strand contained the If the coding DNA strand contained the

following sequence: TAC CGA TTG ACTfollowing sequence: TAC CGA TTG ACT What would the mRNA strand be?What would the mRNA strand be?

AUG GCU AAC UGAAUG GCU AAC UGA What would the tRNA sequence be?What would the tRNA sequence be?

UAC CGA UUG ACUUAC CGA UUG ACU What would the amino acid sequence be?What would the amino acid sequence be?

(base it on the mRNA strand!)(base it on the mRNA strand!)

methionine, alanine, asparagine, methionine, alanine, asparagine, “stop”“stop”