Name _______________________________________________ hour ________ date ______
11.1 Guided Reading Activity: DNA: The Molecule of Heredity
Page 287
1. Read the Italicized paragraph. How much information can be carried on a DNA molecule?
What Is DNA?
2. What determined an organisms traits?
3. DNA achieves this control by producing _____________________.
4. What does DNA contain the complete instructions for?
Page 287 – 289
The structure of DNA
5. DNA is a polymer made of
______________________________________________________________________.
6. Describe nucleotides.
7. What is the simple sugar in DNA called? _________________________________________
8. Define Nitrogen Base _________________________________________________________
__________________________________________________________________________
9. List the 4 Nitrogenous bases.
_______________________________
_______________________________
_______________________________
_______________________________
10. Nucleotides join together to form long _____________________.
11. What forms the backbone of a DNA chain?
_______________________________ and _______________________________
12. Which part is like teeth on a zipper? _________________________________
13. Amount Adenine = amount _____________________
Amount Guanine = amount_____________________
14. What joined the 2 chains of nucleotides together _________________________
15. What type of bond actually holds the bases together? ____________________
16. The strands are complimentary, meaning that the bases on
strand…._________________________________________________________________________
17. Define: Double Helix
18. Examine Figure 11.2: From what you have already read, answer the following:
 The bright yellow spheres along with the blue and green ones make up the backbone of DNA.
What two compounds are theses? ____________________ and _________________
 The Horizontal connecting pieces are compared to the teeth of a zipper, what are they made of?
________________________________.
Page 289 - 290
The importance of nucleotides
19. True or false: All organisms contain the same four nucleotides (bases)
20. How are they so different from each other if they have the same 4 bases (nucleotides)?
21. The closer the relationship between the two organisms, the ___________________ the
_____________________ in their order of ____________ ______________________.
22. What can nucleotide sequences be used to determine?
Page 290 - 291
Replication of DNA
23. Before a cell can divide in mitosis or meiosis, it must first make
a copy of its ___________________.
24. Define : DNA Replication
Page 291 – 292
How DNA replicates
25. DNA replication begins as an ________________________ breaks the
__________________________ between __________________________ that hold the two strands
together.
26. As the DNA continues to _____________, free nucleotides bind to their complementary base pair..
27. Another ______________ bonds these two nucleotides into a ____________________.
28. Each new strand formed is a _________________________ of one of the original strands.
29. The result is the formation of ____________________________________, each of which is
identical to the original DNA molecule.
Pages 292-293
30. Copying DNA
a. When is DNA copied? __________________________________________________
b. Separation of Strands. Describe what is happening at this stage.
c. Base Pairing: ________________ nucleotides base pair with _____________ nucleotides.
Thyamine pairs with _____________________ and
cytosine pairs with ____________________
d. Bonding of Bases: ___________________ and ______________ bond to form the
__________________________.
e. Results of Replication: What is produced? _______________________________________
Answer questions 1-5 on page 293
1.
2.
3.
4.
5.
DNA molecule Complementary Strand
G
G
C
A
G
T
T
C
A
T
G
C