Download Answer Key Lab DNA Structure

Part 1: DNA to Protein Exercise
The following DNA sequence is part of the gene that controls dimples. Decode the DNA message into mRNA,
tRNA and finally amino acids. Use the genetic code chart to fill in the table below. NOTE: The genetic code is
based on mRNA (not DNA or tRNA). When you have finished this, you will be able to determine the
phenotype of the person the DNA came from. (If arginine is the 3rd amino acid, the person will have dimples.)
DNA
C
G
A
G
T
C
G
C
A
T
A
A
mRNA codon
G
C
U
tRNA anticodon
C
G
A
Amino Acid
Ala
C
A
G
G
U
C
Gln
C
G
U
G
C
A
Arg
A
U
U
U
A
A
Ile
1. Does the person with the
sequence above have dimples?
Second
Yes
2. What two great tasks are
carried out by our genetic
machinery?
DNA replication and protein synthesis
3. What name do we call a threenucleotide sequences of mRNA?
codon
4. How many DNA bases does it
take to code for an RNA codon?
3
5. How many amino acids does an
RNA codon code for?
1
6. What brings amino acids to the
ribosome?
transferRNA
7. What is the difference between transcription and translation?
Transcription happens when information from the DNA template is transcribed onto messenger RNA.
Translation happens when information from RNA is translated into proteins.
8. True or false: Most of the DNA in the human genome codes for proteins.
False. Only 2% of your DNA codes for protein.
Part 2: Protein Synthesis Exercise
DNA:
3’
A G
C C G T A G A A T T
1. Using this strand of DNA as a template, DRAW A PICTURE of the complete DNA
molecule. Include ALL parts of the DNA molecule. You do not need to draw your
molecule with atomic accuracy.
3’
AGC CGT AGA ATT
5’
TCG
GCA TCT
5’
TAA 3’
2. Now draw a complete picture of the mRNA strand that will be made from this DNA.
Label the 5’ and 3’ ends of your mRNA strand. (Use the given DNA strand at the top of
this page as your template…)
5’
UCG GCA UCU UAA 3’
3. Carefully indicate the codons present in the mRNA strand from question 2.
5’
UCG GCA UCU UAA 3’
4. Draw a COMPLETE picture of all the tRNA molecules that will match up with the
codons from the previous question. Include ALL APPROPRIATE amino acids in
your picture, and do not mix up their order!
Ser
5’
Ala
Ser
Stop
AGC CGU AGA AUU
tRNA
UCG GCA UCU UAA 3’
mRNA
5. Draw a picture of the completed protein coded for by this strand of DNA
(abbreviations are fine).
Show the amino acids in the same order they would be observed in the finished
protein.
Ser-Ala-Ser
5’