Transcript Genetic Code Notes

The Genetic Code
Objective: F2 - Explain … process of transcription &
translation …, describe the role of DNA & RNA during
protein synthesis, & recognize that gene expression is a
regulated process
Using the Genetic Code
A. Codon – 3 nitrogen bases of
mRNA in a row that code for a
specific amino acid
B. Genetic code – a chart that shows
the amino acids that correspond to
the codons of mRNA
C. How nucleotides are read – 3 at
1. 3 DNA nucleotides =
2. 3 mRNA nucleotides =
3. tRNA nucleotides =
one time
CAT
GUA
CAU
D. Reading the Genetic Code
1. 1st letter (base) of the codon = G
2. 2nd letter (base) of the codon = U
3. 3rd letter (base) of the codon = A
Using the genetic code on the front, which
amino acid does the above codon
produce? ________
Valine
E. To “make” a protein
1. Transcribe the given DNA strand into
mRNA
2. Look up the mRNA codons on the
Genetic Code table
Practice:
DNA sequence TAC AAA GTA TGG GGC ATC
1. Transcribe
into mRNA
2. Translate into
an amino acid
sequence
AUG UUU CAU ACC CCG UAG
Met- Phe- His- Thr- Pro- stop
DNA
mRNA
codon
tRNA
anticodon
Amino acid
4.
ACC
UGG
ACC
Tryptophan (TRP)
5.
AGA
UCU
AGA
Serine
6.
TTT
AAA
UUU
Lysine
7.
ACT
UGA
ACU
Stop
Although there are
only 20 amino
acids in the human
body, thousands
of proteins exist
because the
sequence and
number of amino
acids are different.