Name:___________________________
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. ____________________
Directions: Complete each sentence.
7. Guanine, cytosine, thymine, and __________________ are the four __________________ in DNA.
8. In DNA, guanine always forms hydrogen bonds with __________________.
9. The process of __________________ produces a new copy of an organism’s genetic information, which is
passed on to a new cell.
10. The double coiled, “staircase” shape of DNA is called a __________________.
Directions: Answer each question in complete sentences.
11. What do the letters DNA stand for?
_________________________________________________________________________
12. Where is DNA found? ____________________________________________________
1
13.
Label the nucleotides (A, T, G, C) in the DNA molecule below. Which are purines? Pyrmidines?
14. Which enzyme is responsible for “unzipping” the DNA double helix?
_________________________________________________________________________
15.
Why is DNA replication important to the growth and development of a multi-cellular organism?
_________________________________________________________________________
_________________________________________________________________________
DNA Replication Practice Below are the 3 steps in DNA replication. Follow the directions for each step and then
answer the questions below.
1.
-Color the DNA molecule red.
-What does the diagram to the right show happening
to the DNA molecule? (Explain the first step in DNA replication)
___________________________________________________
___________________________________________________
___________________________________________________
2.
-Color the new DNA nucleotides in the diagram to
the right blue. Color the original DNA strands red.
-What happens to the DNA molecule during the second
step of DNA replication?
____________________________________________
____________________________________________
____________________________________________
2
3.
-Color the new DNA strands blue and color the other DNA
strands red.
-What happens during the third step of DNA replication?
_______________________________________________
_______________________________________________
_______________________________________________
-Which color, red or blue, represents the original
template? ____________
16.
A
T
C
C
G
T
G
The model of DNA below is ready to be copied. Compared to the original double helix, evaluate the copies
made during three attempts of DNA replication. List any errors with the replication if they occurred:
Replication #1
T
A
G
G
C
A
C
Replication #2
A
T
T
A
C
G
C
G
G
T
G
AND
AND
C
A
C
A
T
T
C
A
G
T
G
A
G
G
C
A
C
A
T
C
C
T
A
G
G
G
T
G
C
A
C
List problems if any:
_______________________
_______________________
_______________________
_______________________
_______________________
_______________________
Original
List problems if any:
_______________________
_______________________
_______________________
_______________________
_______________________
_______________________
A
T
C
C
T
A
G
G
G
T
G
C
A
C
17. 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
A
A
A
T
G
T
G
G
G
C
G
C
C
C
C
G
C
G
T
T
T
A
T
A
A
A
A
T
A
T
T
T
T
G
C
A
A
A
T
A
T
A
3