Decoding the Genetic Code

Keratin is one of the proteins found in hair. The gene for keratin is transcribed and translated by certain skin cells. The series of letters below represent the sequence of nucleotides in a portion of the DNA molecule. The DNA contains a “recipe” to make the keratin protein found in our hair. You need to transcribe the DNA sequence into mRNA and then transcript this mRNA into a chain of amino acids that make up Keratin. The process of decoding DNA into a strand of amino acids is called protein synthesis. Your body must produce the protein keratin to maintain healthy hair. If there is any change in the amino acid sequence, it will result in making the wrong protein, and keratin will not be made, therefore affecting your hair.

PROCEDURE:

1. TRANSCRIBE the DNA sequence below into mRNA

2. Using the table at the end of the lab, TRANSLATE the mRNA into a sequence of amino acids.

DNA / mRNA / Amino Acid
ACA
GCA
CTT
AAA
AGG
CGA
GGC
CAT
TTC
CAG

3. Now transcribe and translate the portion of keratin in table 2 below. Note how this sequence is different.

DNA / mRNA / Amino Acid
ACA
GCA
CTT
ATA
AGG
CGA
GGC
CAT
TTC
CAG

a. What type of mutation has occurred in table 2?

b. What was the result of this mutation?

5.  Transcribe and translate the table 3 below.

DNA / mRNA / Amino Acid
ACA
GCA
TTA
AAA
GGC
GAG
GCC
ATT
TCC
AG

A.  What type of mutation has occurred in the table above?

B.  What does this type of mutation result in?

C.  How does this mutation affect the sequence of amino acids for keratin?

QUESTIONS

1.  Why is DNA important to protein synthesis?

2.  Where does transcription occur within the cell?

3.  Where does translation occur within the cell?

4.  Explain the process of Transcription. (Include all the enzymes).

5.  Explain the process of translation.

6.  What is a codon?

7.  What is an exon?

8.  Are introns important? Explain

9.  Does the entire molecule of DNA unwind and unzip during protein synthesis? Explain.

10.  How are chromosomal mutations different then gene mutations?

11.  Is the mutation in table three germ or somatic, on the chromosomal or gene level?