Name _________________________________
Date _____________________
Period __________
Part 1: DNA’s Instructions for Insulin
Introduction:
Below are two partial sequences of DNA bases (shown for only one strand of DNA). Sequence 1 is from a human and sequence
2 is from a cow. In both humans and cows, this sequence is part of a set of instructions for controlling the production of a
protein. In this case, the sequence contains the gene to make the protein insulin. Insulin is necessary for the uptake of sugar
from the blood. Without insulin, a person cannot use digest sugars the same way others can, and they have diabetes.
Materials:
Paper, pencil, codon table
Procedure:
1. Using the DNA sequence given in table 1, make a complimentary RNA strand for
the human. Write the RNA directly below the DNA strand.
2. Repeat step 1 for the cow. Write the RNA directly below the DNA strand in table.
3. Use the codon table to determine what amino acids are assembled to make the insulin
protein in both the cow and the human. Write your amino acid chain directly below the RNA sequence.
Table 1
DNA
RNA
Amino Acids
Sequence 1 Human
3’ T A C C C A T A G C A C G T T A C A A C G T G A A G G T A A 5’
Table 2
DNA
RNA
Amino Acids
Analysis:
Sequence 1 Cow
3’ T A C C C G T A G C A T G T T A C A A C G C G A A G G C A C 5’
1. The DNA sequence is different for the cow and the human, but the amino acid chain produced by the sequence is almost the
same. How can this happen?
2. Diabetes is a disease characterized by the inability to break down sugars. Often a person with diabetes has a defective DNA
sequence that codes for the making of the insulin protein. Suppose a person has a mutation in their DNA, and the first triplet
for the gene coding for insulin is C C C (instead of C C A). Determine what amino acid the new DNA triplet codes for. Will this
person be diabetic?
3. What if the first triplet was C A A ?
4. How is it that a code consisting of only four letters, as in DNA ( A, T, G, C ) can specify all the different parts of an organism
and account for all the diversity of organisms on this planet?
DNA sequences are often used to determine relationships between organisms. DNA sequences that code for a particular gene
can vary widely. Organisms that are closely related will have sequences that are similar. Below is a list of sequences for a few
organisms:
Human
Pig
Chimpanzee
Cricket
5.
CCA
CCA
CCA
CCT
TAG
TGG
TAA
AAA
CAC
AAA
CAC
GGG
CTA
CGA
CTA
ACG
Based on the sequences, which two organisms are most closely related?
6. An unknown organism is found in the forest, and the gene is sequenced, and found to be C C A T G G A A T C G A, what
kind of animal do you think this is?
Part 2: How Does DNA Determine the Traits of a SNORK?
Introduction: In this simulation, you will examine the DNA sequence of an imaginary organism known as the Snork. Snorks
were discovered on the planet Dee Enae in a distant solar system. Snorks only have one chromosome with 6 genes on it. You
job is to analyze the genes of its DNA and determine what traits the organism has.
SNORK DNA AND TRAITS
tRNA triplet
Amino Acid Number
Amino Acid Sequence
Trait
ACC
20
20-11-13
hairless
AGC
16
20-12-13
hairy
CGA
2
20-21-21
plump
AAC
4
13-14-15
skinny
CGC
3
16-2 - 5
4 legged
GGG
5
16-4 - 5
2 legged
AGG
7
12-7-8
round head
AAA
8
5-7-8
block head
UUU
9
9-8 - 8
no tail
GGU
12
9-4 - 8
tail
UAU
13
11-3-2
slanted eyes
CCC
1
11-3-3
wide round eyes
AUC
6
6-6-10
male
CUA
10
6-6-14
female
GGA
11
Observations and Analysis of Snork DNA
You are given a chromosome from a Snork with the following sequence. Each gene has only 3 amino acids. Your job is to
determine the sequence of amino acids for your specimen. Write the complimentary mRNA, tRNA, the amino acid (A.A.)
sequence it codes for and the related trait in the chart below.
DNA
ACCGGTTAT|AGCCGAGGG|TTTAACAAA|GGACGCCGA|
GGGAGGAAA|ATCATCCTA
mRNA
tRNA
A.A.
Trait
Draw your Snork in the space below. Be creative!