Download Transfer RNA and Protein Building Name_________________

Transfer RNA and Protein Building
Name_________________
Paper Lab
Prd.____Date___________
RNA produced in the nucleus of a cell moves out of the nucleus toward the cell’s ribosomes. It
carries with it a specific sequence of nitrogen bases copied from the DNA. RNA carries the
genetic message of the chromosomes into the cell. This type of RNA is called
_______________________________________.
At the ribosomes, the mRNA directs the building of ___________________. Proteins are
important molecules used for: building cell parts, as transport molecules, as enzymes and
hormones and numerous other functions. Proteins are built of long chains of
______________________________. Each protein must be built with the correct sequence of
amino acids. How does mRNA direct the ribosome to put the amino acids in the correct
order? This involves another type of RNA: _______________________________, or tRNA.
Part A. Protein Formation
Molecules of tRNA are composed of many RNA nucleotides, just like mRNA. However, there
are two locations in particular that are very important for the function of the tRNA. First, at
the ____________________end there are 3 bases. These 3 bases can be any combination of
Guanine, Adenine, Cytosine, or ____________________. These 3 bases form a triplet called
the ____________________. This triplet of bases matches a triplet of bases on the mRNA. The
triplet of bases on the mRNA is called the __________________.
As you can see from the tRNA diagram to the
left, the anticodon has a sequence of GAA.
What would be the codon on the mRNA that
would match this anticodon? ____ ____ ____
In addition to the terminal end, at the other end of the tRNA, there is an amino acid
attachment site. Each tRNA has a specific amino acid that can bond to it. By means of
____________________, tRNA molecules pick up amino acids in the cytoplasm of the cell. The
tRNA molecule then brings the amino acid to the ______________________.
tRNA molecules are like taxi cabs.
They bring their amino acid
“passengers” to the ribosome, drop
them off, then go back out to the cell
and pick up another amino acid.
The difference in this analogy,
however, is that each tRNA “taxi cab”
can only pick up a particular amino
acid “passenger”. It’s almost like it
has a sign on top that says, “Available
for glycine”, or “Available for
alanine”!
The process by which the amino acids are placed in the correct sequence at the ribosome is
called Translation. This process “translates” or “reads” the code from the mRNA and as each
tRNA brings an amino acid, it lines them up correctly.
To complete the paper lab, follow the teachers’ instructions and demonstration of how the
process of translation works in a cell.
Questions:
1. If the mRNA sequence (the codon) is GUC, what is the sequence of the tRNA that
matches this (what is the anticodon)? _____ ____ ____
2. What amino acid does this tRNA carry? ___________________(see your model)
3. If the mRNA sequence (the codon) is CGA, what is the sequence of the tRNA that
matches this (what is the anticodon)? _____ ____ ____
4. What amino acid does this tRNA carry? ___________________(see your model)
How were you able to tell which tRNA matched up to the mRNA?
______________________________________________________
5. A base sequence of A, A, A in mRNA could only join with what sequence of bases in
tRNA? _______________
6. A base sequence of U, C, C in tRNA will bond to what sequence of mRNA?
____________________
7. How many bases on the mRNA are responsible for the coding of one amino acid?
_____
Amino Acid Codon Chart
8. What specific amino acid is brought to the ribosome if the mRNA code is UAU?
_______________________
9. What specific amino acid is brought to the ribosome if the mRNA code is ACA?
_______________________
10. If the tRNA anticodon is UUG, what amino acid does it carry to the ribosome?
_______________________ (Note: this chart is the mRNA codons).
11. If the tRNA anticodon is GAG, what amino acid does it carry to the ribosome?
_______________________(Note: this chart is the mRNA codons).
12. What is the codon for Methionine? _____________________What is unique about
Methionine?__________________________________________________________
13. What are the possible codons for Lysine? __________________________________
For the following questions, continue to use the mRNA Codon Chart on the previous
page to help with your answers.
DNA Sequence:
A
A
T
G
G
G
A
T
A
A
C
C
G
T
T
A
T
T
mRNA Sequence:
tRNA Sequence:
Amino Acid
Sequence:
Mutations and Base Sequences:
Rarely does the DNA code of instructions make an error in directing cells to form a
protein. When it does, however, the error is called a ______________________. A
mutation may result in a different type of protein.
Hemoglobin is a large protein found in red blood cells. Hemoglobin carries
_______________________, a necessary element for cellular respiration. Without
oxygen, cells will die and the proper formation of this important protein is crucial for
human health.
Hemoglobin results from the proper arrangement of almost 600 amino acids. (That’s a
LARGE protein!). Most humans have the correct type of hemoglobin. However, in
some people, the arrangement of amino acids is incorrect. These people have a
genetic disease called sickle-cell anemia. Their red blood cells are sickle-shaped
instead of round. The hemoglobin in these cells does not transport oxygen effectively
and these cells get stuck in capillaries, causing severe problems.
In the diagram to the left, you can see that the
normal red blood cell is round. It can easily flow
through the very narrow capillaries and blood
vessels.
However, the sickled cell gets stuck in capillaries,
especially in joints. This will block the blood flow to
those areas that are connected to that capillary and
cells will die due to lack of oxygen.
A small portion of a normal hemoglobin protein has this amino acid sequence:
Proline
Glutamic Acid
Glutamic Acid
Lysine
A small portion of a sickled hemoglobin protein has this amino acid sequence:
Proline
Valine
Glutamic Acid
Lysine
Only one out of almost 600 amino acids is incorrect and it causes a deadly incurable
genetic disease.
Use the following transfer RNA Anticodons to answer the following questions:
Amino Acid:
Proline
Glutamic Acid
Lysine
Valine
tRNA Anticodon:
GGG
CUU
UUU
CAA
14A. What is the sequence of tRNA anticodon bases in this small section of a normal
hemoglobin molecule: _______________________________________________
14B. What is the sequence of tRNA anticodon bases in this small section of a sickled
hemoglobin molecule: _______________________________________________
Use your answers from Qu. 14 above to help answer these:
15A. What is the sequence of mRNA codons that would match the tRNA anticodons in
the normal hemoglobin? ______________________________________
15 B. What is the sequence of mRNA codons that would match the tRNA anticodons in
the sickled hemoglobin? ______________________________________
Use your answers from Qu. 15 above to help answer these:
16A. What is the sequence of DNA bases in this segment from a normal hemoglobin?
__________________________________________
16B. What is the sequence of DNA bases in this segment from a sickled hemoglobin?
__________________________________________
What is the error? (Where is the mutation in this sequence of DNA?)
____________________________________________________________________
The definition of a mutation is:
_____________________________________________________________________
What is the function of mRNA?
_____________________________________________________________________
What is the function of tRNA?
_____________________________________________________________________