General Biology Notes CH 12: TRANSLATION A.K.A. PROTEIN

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Transcript General Biology Notes CH 12: TRANSLATION A.K.A. PROTEIN

General Biology Notes
TRANSLATION
A.K.A. PROTEIN SYNTHESIS
Translation Definition:
• the process of converting or
translating the information in mRNA
into a sequence of amino acids that
makes up proteins.
NOTE:
• Before translation can begin, transcription
of the DNA into mRNA must occur.
There are three types of RNA
involved in protein synthesis:
mRNA, rRNA and tRNA
3 steps:
1. Initiation: mRNA attaches to the
ribosome (rRNA). (The rRNA slides along
the mRNA like a bead on a string.)
• rRNA “reads” the mRNA in groups of
three nucleotides called a codon.
• Translation always begins with a special
codon (AUG) called the initiator or start
codon.
NOTE:
• there are 20 different amino acids and
64 different codons. Each amino acid
may have more than one codon but
each codon specifies for only one
amino acid.
mRNA codon chart
2. Elongation:
• Transfer RNA (tRNA) carries or “taxis”a
specific amino acid determined by the
anticodon to the ribosome.
• The anticodon of tRNA pairs with the
complementary codon on mRNA.
• As the tRNA’s line up the amino acids,
peptide bonds form between amino acids
linking them into a protein.
• The tRNA’s are recycled back to pick up
more amino acids.
3. Termination:
• the protein is released from the ribosome
when a “stop” codon is reached. There
are three special “stop” codons: UAA,
UAG and UGA