1. 10.2 DNA and RNA are polymers of nucleotides
DNA is a nucleic acid, made of long chains of nucleotides
Phosphate group
Nitrogenous base
Nitrogenous base (A, G, C, or T)
Sugar
Phosphate group
Nucleotide
Thymine (T)
Sugar (deoxyribose)
DNA nucleotide
Polynucleotide
Sugar-phosphate backbone
Figure 10.2A

2. DNA has four kinds of bases, A, T, C, and G
Thymine (T)
Cytosine (C)
Adenine (A)
Guanine (G)
Pyrimidines
Purines
Figure 10.2B

3. Nitrogenous base (A, G, C, or U)
RNA is also a nucleic acid
RNA has a slightly different sugar
RNA has U instead of T
Nitrogenous base (A, G, C, or U)
Phosphate group
Uracil (U)
Sugar (ribose)
Figure 10.2C, D

4. 10.3 DNA is a double-stranded helix
James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin
Figure 10.3A, B

5. The structure of DNA consists of two polynucleotide strands wrapped around each other in a double helix
1 chocolate coat,
Blind (PRA)
Figure 10.3C
Twist

6. Hydrogen bonds between bases hold the strands together
Each base pairs with a complementary partner
A pairs with T
G pairs with C

7. Partial chemical structure
Three representations of DNA
Hydrogen bond
Ribbon model
Partial chemical structure
Computer model
Figure 10.3D

8. 10.4 DNA replication depends on specific base pairing
In DNA replication, the strands separate
Enzymes use each strand as a template to assemble the new strands A A
Nucleotides
Parental molecule of DNA
Both parental strands serve as templates
Two identical daughter molecules of DNA
Figure 10.4A

9. Untwisting and replication of DNA
Figure 10.4B

10. 10.5 DNA replication: A closer look
DNA replication begins at specific sites
Parental strand
Origin of replication
Daughter strand
Bubble
Two daughter DNA molecules
Figure 10.5A

11. Each strand of the double helix is oriented in the opposite direction
5 end
3 end P P P P P P P P
3 end
5 end
Figure 10.5B

12. Overall direction of replication3
DNA polymerase molecule
How DNA daughter strands are synthesized
5 end 5
Daughter strand synthesized continuously
Parental DNA 5 3
Daughter strand synthesized in pieces 3 P 5
The daughter strands are identical to the parent molecule 5 P 3
DNA ligase
Overall direction of replication
Figure 10.5C