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Name ________________________
Build-a-Bug
Protein Synthesis: Transcribing & Translating the DNA Code
General Information
“Bugs” are insects. Insects, like all living organisms have certain traits in common. All
insects have antennae attached to the head (2-4 pairs), wings attached to the thorax (2-4 pairs),
and three pairs of legs attached to the thorax. The three body regions are pictured below.
Head
Thorax
Abdomen
Even though “bugs” share some traits with all other bugs, each is an individual. Their
DNA structure codes for their proteins and therefore determines their individual differences.
Purpose
To create an “original bug” by transcribing and translating its DNA code. Your bug must
be genetically correct according to the code you are assigned. All other creative embellishments
are allowed, even color enhancement is encouraged. All traits must be represented according to
the DNA code you are assigned.
Materials
Drawing paper
Colored pencils
Magic Markers
“Bug” reference books
Construction paper
Rulers
Toothpicks
Scissors
Glue
Tape
Pipe cleaners
Cotton balls
Q-tips
Imagination!!
Procedure
DNA
1. You will be given the DNA of your bug. When you receive this, past the code onto the provided space below. Now copy this
code in the correct space on Table 1.
Transcription
Before the synthesis of a protein begins, the corresponding RNA molecule is produced by RNA transcription. One strand of the DNA
double helix is used as a template by the RNA polymerase. During this step, mRNA migrates from the nucleus to the cytoplasm.
During this step, mRNA goes through different types of maturation including one called splicing, when the non-coding sequences are
eliminated. The coding mRNA sequence can be described as a unit of three nucleotides called a codon.
2. In Table 1., transcribe your DNA strand into the “language” of mRNA. Remember, RNA
contains uracil instead of thymine.
Translation
The ribosome binds to mRNA at the start codon (AUG) that is recognized only by the initiator tRNA. The ribosome proceeds to the
elongation phase of protein synthesis. During this stage, complexes, composed of amino acids linked to tRNA, sequentially bind to
the appropriate codon in mRNA by forming complementary base pairs with the tRNA anticodon. The ribosome moves from codon to
codon along the mRNA. Amino acids are added one by one, translated into polypeptidic sequences dictated by DNA and represented
by mRNA. At the end, a release factor binds to the stop codon, terminating translation and releasing the complete polypeptide from
the ribosome.
3. Locate the initiator codon on your strand of mRNA. Using the Universal mRNA Codon Chart on the next page, determine the
name of the amino acid that each codon codes for. One specific amino acid can correspond to more than one codon. This
genetic code is said to be degenerate. Write the abbreviation of the amino acids, in their proper order, in Table 1.
4. Using the polypeptide chain made by the DNA of your bug, determine the particular coded traits your bug will express. Use
the provided key to do this and write the trait on Table 1.
5. Construct your bug using the provided supplies and your creativity!!
6. In a well-developed paragraph, explain the traits of your bug. In addition to the traits determined by the DNA strand, use your
creativity to describe other characteristics of your organism (habitat, diet, personality, etc.). Also, indicate if there are any
other bugs in the room that may be of the same species (i.e. have similar traits to your bug). Write this on notebook paper.
Transfer RNA is a single strand of RNA that loops back on itself. Each transfer RNA molecule has two important sites of attachment.
One site, called the anitcodon, binds to the condon on the messenger RNA molecule. The other site attaches to a particular amino
acid. During protein synthesis, the anticodon of a transfer RNA molecule base pairs with the appropriate messenger RNA codon.
7. Indicate what the tRNA sequence would be for your bug in the appropriate place on Table 1. Use the mRNA that you decoded
to do this.
Universal mRNA Codon Chart
First
Letter
U
C
A
G
U
phenylalanine
phenylalanine
Leucine
Leucine
Leucine
Leucine
Leucine
Leucine
Isoleucine
Isoleucine
Isoleucine
Methionine
Valine
Valine
Valine
Valine
Second Letter
C
A
serine
tyrosine
serine
tyrosine
serine
stop
serine
stop
proline
histidine
proline
histidine
proline
glutamine
proline
glutamine
threonine
asparagine
threonine
asparagine
threonine
lysine
threonine
lysine
alanine
aspartate
alanine
aspartate
alanine
glutamate
alanine
glutamate
G
cysteine
cysteine
stop
tryptophan
arginine
arginine
arginine
arginine
serine
serine
arginine
arginine
glycine
glycine
glycine
glycine
Third
Letter
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
Coded Traits
Start Codon = AUG (Methionine)
Smooth Wing ------------------------------ Lysine, Arginine
Wrinkled Wing ---------------------------- Lysine, Serine
Red Eye ------------------------------------ Asparagine, Arginine
Other Color -------------------------------- Asraragine, Serine
Rounded Abdomen ----------------------- Phenylalanine, Tyrosine
Pointed Abdomen ------------------------- Phenylalanine, Cysteine
Striped Thorax ----------------------------- Leucine, Proline
Solid Color Thorax ------------------------ Leucine, Histidine
Pointed Head ------------------------------- Isoleucine, Aspartic Acid
Rounded Head ----------------------------- Isoleucine, Asparagine
Straight Antennae ------------------------- Proline, Glycine
Wavy Antennae --------------------------- Proline, Glutamic Acid
Long Legs---------------------------------- Tryptophane, Histidine
Short Legs --------------------------------- Tryptophane, Phenylalanine
Elongated Thorax ------------------------- Valine, Glutamine
Square Thorax ----------------------------- Valine, Methionine
Hairy Legs --------------------------------- Alanine, Glycine
Smooth Legs ------------------------------ Alanine, Cysteine
Chirp Voice ------------------------------- Lysine, Leucine
Peep Voice -------------------------------- Lysine, Methionine
Stinger ------------------------------------- Threonine, Valine
No Stinger -------------------------------- Threonine, Tryptophane
Feet With Claws ------------------------- Cysteine, Histidine
Feet, No Claws --------------------------- Cysteine, Asparagine
Spotted Wings ---------------------------- Glycine, Arginine
Striped Wings ---------------------------- Glycine, Isoleucine
Stop Codons = UAA, UAG, UGA
Table 1.
DNA
mRNA
Amino
Acid
Trait
tRNA
DNA
mRNA
Amino
Acid
Trait
tRNA
DNA
mRNA
Amino
Acid
Trait
tRNA