Instructor’s Copy
Lab Worksheet – The Pattern
Part 1: Assembling the Nucleotides
A. Each nucleotide is composed of a deoxyribose sugar, a phosphate and a nitrogen base. There are
4 different bases in DNA: adenine, thymine, guanine and cytosine. Nucleotides are named for
the nitrogen base that is attached, for example, an adenine nucleotide has a sugar, a phosphate
and an adenine base. You will make 2 adenine, 3 thymine, 1 guanine and 3 cytosine nucleotides.
B. Line the nucleotides up in the following order: 5’TCTAGCTCA3’. The numeric superscripts
indicate the direction in which the DNA sequence is read, from 5 to 3.
1. List the DNA sequence that would match the segment you made if this were DNA replication.
T
C
T
A
G
C
T
C
A
A
G
A
T
C
G
A
G
T
2. In DNA replication, daughter cells are exact copies of the parent cells because they receive
identical copies of the DNA.
3. List the m-RNA sequence that would match this DNA segment if this were protein synthesis.
T
C
T
A
G
C
T
C
A
A
G
A
U
C
G
A
G
U
4. In RNA, the base uracil replaces thymine and the sugar deoxyribose is replaced by ribose.
5. Using the chart shown above, predict the protein chain that would be synthesized from the mRNA sequence formed in #2.
arginine – serine - serine
6. A substitution mutation occurs in the DNA segment that is responsible for the formation of this
m-RNA. The bases actually formed in the m-RNA are AGAUAGAGU. Predict the protein chain
that would be synthesized from this sequence.
arginine – stop - serine
7. If this DNA segment was the beginning of a necessary protein like growth hormone, what
effect might this mutation have on the body?
The growth hormone would not be produced and the person would not grow.
Questions:
1. What are the 3 components of a DNA nucleotide?
A deoxyribose sugar, a phosphate group (phosphoric acid) and a nitrogen base.
2. What is the difference between a cytosine DNA nucleotide and a cytosine RNA nucleotide?
DNA has deoxyribose sugar and RNA has ribose sugar.
3. What base in not present in RNA? thymine
4. What base replaces this one? uracil
5. What base matches up with cytosine? guanine
6. What is the definition of a mutation? A permanent change in the DNA.
7. How could a mutation be passed on to offspring?
It has to be part of the DNA in the egg and sperm (gamete DNA). A mutation in the DNA of
a body cell would not be passed on to the offspring.