Name: ______________________________________________ Score: ____/____
Worksheet – Structure of DNA and Replication
Directions: Label the diagram below with the following choices:

Nucleotide

Deoxyribose


Base pair

Hydrogen bond

Phosphate
group
Nitrogenous
base
1. ____________________
6. ____________________
2. ____________________
5.
__________________
4. ____________________
3. ____________________
1
Using the knowledge of base pairing rules (A-T & C-G), answer the following questions:
7.
Label the nucleotides (A, T, G, C) in the DNA molecule below:
2
8.
A nucleotide is made of three parts: a ______________________________ group, a
five carbon ____________________, and a __________________________________ base.
9. Chargaff’s rule states that the DNA of any species contains equal amounts of
___________________________ & ____________________________ and also equal
amounts of ____________________________ & ______________________________.
10. In a strand of DNA, if the percentage of thymine is 30%, what would the
percentage of adenine be? ________________________ What is the percentage of
cytosine? ______________________. What is the percentage of guanine?
__________________________
11. Number the steps of DNA replication in the correct order (1, 2, 3)
______ the two identical daughter strands of DNA separate and finish rewinding
______ helicase unwinds the parent strand of DNA
______ DNA polymerase helps add the complementary bases
12. If the sequence of one single strand of DNA is C-A-A-G-T-A-G-G-C-T, what is the
sequence of the complementary strand?
13. When an error occurs during the process of DNA replication, we call this a
______________________.
3
Original
14. The
model
of DNA to the
right is ready to be copied. Compared to the original double helix,
evaluate the copies made during two attempts of DNA replication.
List any errors with the replication if they occurred:
Replication #1
A
T
T
A
C
G
C
G
G
C
T
A
G
C
Replication #2
A
T
T
A
C
G
C
G
G
C
T
A
G
C
AND
A
T
C
A
G
T
G
T
A
G
G
C
A
C
AND
A
T
C
C
G
T
G
T
A
G
G
C
A
C
List problems if any:
A
T
C
C
G
T
G
T
A
G
G
C
A
C
List problems if any:
15. Complete the diagram on the left. Then circle the areas in the diagram on the right
that show a genetic mutation.
DNA Correctly Copied
DNA Incorrectly Copied
4
A
G
C
T
A
T
A
A
G
C
T
A
T
A
T
C
G
A
T
A
T
A
G
C
T
A
T
A
T
C
G
A
T
G
T
16. Explain how the mutations might have been caused in the diagram above.
5
G
G
C
T
A
C
A
T
C
G
A
T
A
T