Name _________________________________________
Period _____ Date __________
SNORKS
Today, you will examine the organism known as the Snork. Snorks were discovered were discovered on the planet Dee
Enae in a distant solar system. Snorks only have one chromosome with 6 genes on it. Your job is to analyze the genes of
its DNA and determine what traits the organism has.
SNORK DNA AND TRAITS
mRNA
ACC
AGC
CGA
AAC
CGC
GGG
AGG
AAA
UUU
GGU
UAU
CCC
AUC
CUA
CCA
Amino Acid Number
20
16
2
4
3
5
7
8
9
12
13
1
6
10
11
Amino Acid Sequence
20-11-13
20-12-13
20-4-4
13-6-1
16-2-5
16-4-5
12-7-8
5-7-8
9-8-8
9-4-8
11-3-2
11-3-3
6-6-10
6-6-12
Trait
Hairless
Hairy
Plump
Skinny
4 legged
2 legged
Round head
Block head
No tail
Tail
Squinty eyes
Wide round eyes
Male
Female
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, and the amino acid
(a.a.) sequence it codes for, and the related trait in the chart below.
DNA
mRNA
a. a
Trait
TGG-CCT-ATA
ACC-GGA-UAU
ATA-TAG-GGG
TCG-TTG-CCC
CCC-TCC-TTT
AAA-TTG-TTT
GGT-GCG-GCT
TAG-TAG-GAT
20-11-13
hairless
SOME HUMAN PRACTICE!
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 digest sugars the same way others can, and they
have a disease called diabetes.
PROCEDURE:
1. Using the DNA sequence given in table 1, make a complimentary RNA strand for the human. Write the mRNA
strand directly below the DNA strand.
2. Repeat step 1 for the cow.
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 mRNA sequence.
HUMAN
DNA
CCATAGCACGTTACAACGTGAAGGTAA
mRNA
Amino Acids
COW
DNA
CCGTAGCATGTTACAACGCGAAGGCAC
mRNA
Amino Acids
ANALYSIS
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 messes up the code for making insulin. Suppose a person has a mutation in their
DNA, and the first triplet for the gene coding for insulin is CCC (instead of CCA). Determine what amino acid the
new DNA triplet codes for. Will this person be diabetic?
3. What if the first triplet was CAA?
4. 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.
Based on the sequences, which two organisms are most closely related?
Human
CCA TAG CAC CTA
Pig
CCA TGG AAA CGA
Chimpanzee
CCA TAA CAC CTA
Cricket
CCT AAA GGG ACG
5. An unknown organism is found in the forest, and the gene is sequenced. It is found to be CCA TGG AAT CGA.
What kind of animal do you think this is?