Transcript From DNA to Protein: Transcription and Translation

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 Ribosomes
click once on image to start
http://www.youtube.com/watch?v=kbB2kMkmb0w
Pair Share
Review with your table partner the overall
process of translation.
.
Translation Animation
http://www.stolaf.edu/people/giannini/flashani
mat/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
anticodon
UAC
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