Gene to Protein Part 2: Translation

After the mRNA transcript leaves the nucleus it goes to a ribosome (site of protein synthesis).

Protein Structure Review

•Proteins are chains of amino acids.

•There are 20 possible amino acids in proteins.

The Genetic Code

Each amino acid is encoded by a sequence of 3 nucleotides.

mRNA codons Every 3 nucleotides in a mRNA strand that

encodes one amino acid in the protein is called a codon.

The Genetic Code is universal. All organisms build the same protein from a given sequence of DNA.

tRNA: the translator molecule

tRNA molecules:• Folded piece of RNA• Exposed 3 nucleotide

sequence called an anticodon. (complementary to a codon).• Attached amino acid

corresponding to the codon.

Pair Share

Discuss with your table partner:

The similarities and differences between mRNA and tRNA in terms of structure and function.

Both mRNA and tRNA are made of chains of nucleotides•tRNA’s are folded and have an attached amino acid.

Both are involved in translation to produce a protein. • mRNA’s are a copy of a gene to produce a specific protein•An “army” of tRNA’s in each cell work to produce all the proteins needed in a cell by translating the mRNA (matching up the correct amino acid)

•A tRNA with an anticodon complementary to the mRNA codon pairs up, carrying the corresponding amino acid.•A second tRNA pairs with the next codon, and the two amino acids are joined by a peptide bond.•The mRNA is slide down the ribosome bringing the next codon to the tRNA binding site.•This process continues, building the protein, until a stop codon is reached.

Translation Video Click once on image to start

http://www.youtube.com/watch?v=z-32M043rfI

Another Translation Video with Ribosomesclick once on image to start

http://www.youtube.com/watch?v=kbB2kMkmb0w

Pair Share

Review with your table partner the overall process of translation.

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Translation Animation

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf

Applying the Concepts

If an mRNA strand has the codon AGU, what anticodon will pair with it in the ribosome?

mRNA codon AGU anticodon UCA

Applying the Concepts Cont.

What amino acid will be attached to this tRNA (that pairs to the codon AGU)?

Serine (Ser)

Applying the Concepts 2

If an mRNA strand has the codon UAC, what anticodon will pair with it in the ribosome?

mRNA codon UAC

anticodon AUG

Applying the Concepts 2 Cont.

What amino acid will be attached to this tRNA (that pairs to the codon UAC)?

Tyrosine (Tyr)

Overview of Transcription and Translation