Transcript Protein Synthesis Continued

Protein Synthesis
Continued
After transcription
RNA editing



After a strand of RNA is constructed by
transcription, it must be altered before it
moves to the cytoplasm
Introns are sections of the RNA that do not
code for a protein and are “cut out” of the
RNA strand (they stay IN the nucleus)
Exons are then spliced back together
because they code for the protein (they
EXIT the nucleus)
RNA language




Remember that RNA codes for a
specific order of amino acids to make
a protein
The RNA strand is read in triplets
(threes) called codons
RNA strand = UCGCACGGUU
Read as = UCG / CAC / GGU
RNA  Proteins


Each codon “codes” for a specific
amino acid
Using the chart on p. 303 decode the
mRNA sequence from the previous
slide.
– UCGCACGGUU
– Serine – Histidine - Glycine
“Special Codons”



The amino acid
methionine “AUG” is
the code for start or
GO
Notice on the chart on
p. 303 that several
sequences code for
“STOP”
These are used to start
or stop protein sythesis
Using the chart

Also notice that more that one codon will
code for the same amino acid
– Ex: Arginine has the codons





CGU
CGC
CGA
CGG
This is called the “wobble effect” so if a
mutation occurs it may not effect the amino
acid sequence.
Amino Acid Sequencing


On page 303, do the “Quick Lab”
You may write your answers in your
notes, however do your OWN work
and I will insure that you have the
answers before you can exit the
classroom.
“Say it With DNA” Project





Each amino acid has been assigned a letter
Create a ONE OF A KIND message using
those letters (a sentence with DHS in it
would be cool)
Figure out the DNA strand, RNA
complementary strand, the codons, and the
amino acid strand and finally the message
Place the above on your poster
Decorate the poster as you wish (Hint:
double helices make excellent accents)