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Translation
Continuing to
make proteins!
The Nature of the Genetic Code
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Proteins are made up of amino acids
(building blocks)
Amino acids linked together form long chains
called polypeptides
Combinations of 3 nucleotides on mRNA
makes a codon (a 3 letter code word)
Each codon specifies a particular amino acid
to be linked (Ex. AAA --- amino acid lysine)
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There are also “start” and “stop” codons
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Start codons begin to make the protein
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Stop codons act like a period at the end of a
sentence --- they finish the process
Steps of Translation
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mRNA attaches to a ribosome.
tRNA (carrying a specific amino acid),
approaches the ribosome.
tRNA anticodons pair up with the mRNA
codon.
Need to begin with a start codon
When the start signal is given, the ribosome
slides along the mRNA to the next codon
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A new tRNA molecule carrying an amino acid
pairs with the 2nd mRNA codon
When the 1st and 2nd amino acids are in
place, an enzyme joins the amino acids
together.
This forms a peptide bond
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The process continues and forms a chain of
amino acids.
The process stops when it reads a stop
codon.
Practice
DNA strand:
ATGCATAGCCTT
mRNA strand:
UACGUAUCGGAA
● What are the codons?
UAC
GUA
UCG
GAA
● What are the anticodons?
AUG CAU AGC
CUU
● What are the amino acids?
Tyrosine, Valine, Serine, Glutamic acid