Download Constructing DNA and RNA out of Paper clips

Constructing DNA and RNA out of Paper clips
Name:________________________
Background: The order of bass in a DNA strand determines the order of amino acids linked in a
polypeptide chain. Polypeptide chains are used to make proteins. In this way, DNA directs the formation
of proteins and controls the activities of the cell. In this activity you will construct a model of DNA. You
will then examine how DNA replicates or duplicates itself. Once you gone through the process of
replication you will also examine the process of transcription and translation.
Materials: Colored paper clips will represent the following bases:
A = blue
T = Green
G= Purple
C= orange
U = yellow
H bonds= silver or black
Procedure:
1. Construct, by connecting the paper clips (which represent nucleotide bases) in the following
DNA sequence.
TAC-ATG-GAA-CTC- AAG-TCC-TGT
2. This single stand represents only part of the DNA double helix. Now using the base pairing rules,
construct a complementary strand to complete the double helix. Record this strand in the DNAleading strand blank on the attached page.
3. Optional (follow teachers directions) Now you have completed a double strand of DNA, in order
to replicate this sequence of DNA you must separate the two strands and build complementary
strands for each strand.
4. Now using the sliver or black paper clips, connect the complementary strands of DNA together,
the black/silver paperclips should represent hydrogen bonds.
5. Using the complementary strand of DNA in step 1, construct a single strand of messenger RNA.
The same base pairing rules apply except, (A) bonds with Uracil (U). Record your results in the
mRNA blank on the attached page.
6. After you have recorded the DNA complementary strand and mRNA strand. Complete the sheet
by filling in the tRNA anticodons, and amino acid sequence for the protein chain.
7. With a colored pencil place a circle around the start codon on mRNA.
8. With a colored pencil place dashed lines between the amino acids which are part of the final
protein chain.(Remember the amino acids will not be coded for until AUG starts translation)
9. Answer the Analysis questions.
DNA: ___ ___ ___ - ___ ___ ___- ___ ___ ___ - ___ ___ ___ - ___ ___ ___ - ___ ___ ___- ___ ___ ___
mRNA___ ___ ___ - ___ ___ ___- ___ ___ ___ - ___ ___ ___ - ___ ___ ___ - ___ ___ ___- ___ ___ ___
tRNA___ ___ ___ - ___ ___ ___- ___ ___ ___ - ___ ___ ___ - ___ ___ ___ - ___ ___ ___- ___ ___ ___
A.A. ___ ___ ___ - ___ ___ ___- ___ ___ ___ - ___ ___ ___ - ___ ___ ___ - ___ ___ ___- ___ ___ __
Analysis:
1. Why do you think complementary base pairing is important for replication?
2. If a sequence of three bases on the DNA codes for a specific amino acid, how many amino acids
will your DNA model code for?_____
3. If the DNA code for amino acids is a sequence of three bases, what is the smallest change in the
arrangement of bases that would result in a change in the protein produces? Explain. (Type of
mutation)
4. Which type of accidental change in the DNA code would have a more serious consequence for
the amino acid sequence; substitution of on DNA base for another, or the addition of an extra
DNA base somewhere in the sequence? Explain.
5. How many codons are on the mRNA?
6. How many amino acids are part of the final protein chain?
7. What would happen if the DNA bases were changed?
8. The attached worksheet has a normal DNA sequence and a Mutant DNA sequence. Complete
the mRNA and amino acid sequence then, with a colored pencil, place a circle around the
abnormal amino acid.