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Translation Learning Targets
• Translation is the synthesis of polypeptides on ribosomes
• The amino acid sequence of polypeptides is determined by mRNA
according to the genetic code.
• Codons of three bases on mRNA correspond to one amino acid in a
polypeptide
• Translation depends on the complementary base paring between codons
on mRNA and anticodons on tRNA
• Use a table of the genetic code to deduce which codon(s) corresponds to
which amino acid
• Use a table of mRNA codons and their corresponding amino acids to
deduce the sequence of amino acids coded by a short mRNA strand of
known base sequence
Translation is the synthesis of polypeptides on
molecular machines called ribosomes.
Ribosomes are bundles of RNA and protein that synthesize
polypeptides from mRNA and tRNAs. The are mostly found in the
cytoplasm of cells.
Codon
Codon
Codon
Codon
Amino Acids are indirectly associated with each codon
Codons- a sequence of three nucleotides that
code for a specific amino acid
Codons, Anticodons, and Transfer RNA (tRNA)
(HHMI Simulation)
What are the consequences of mutations?
In Somatic (any cell other than reproductive) cells:
• Substitution mutations may result in the replacement of one amino acid with a
different amino acid
• Insertion and deletion mutations often result in a frameshift where the entire
codon sequence is changed “downstream” of the mutation.
A frameshift can cause an alteration in the protein’s shape or size. Certain types of
mutations can lead to cancer. But they can also lead to entirely new traits.
What are the consequences of mutations?
• In germ cells or gametes
• Mutations may influence or change the development and
formation of certain traits in the organism
• Could lead to evolution
The development of the
human skull could be
the result of a
frameshift mutation in
the MYH16 gene, found
in apes and chimps,
which is expressed in
their powerful jaw
muscles.
Practice time!
Use the codon charts in your textbooks to fill out the worksheets. What
you don’t finish is homework.