1. The Structure of DNA and RNA

2. Two types of nucleic acid
DNA
RNA
Two strands
Contains Deoxyribose
Contains ACTG
Remains in the nucleus
One strand
Contains ribose
Contains ACUG
Exists in the cytoplasm, originally copied from the DNA.

3. 5 end 3 end 3 end 5 end Hydrogen bond 3.4 nm 1 nm 0.34 nm (a)
Figure 16.7
5 end C G
Hydrogen bond C G
3 end G C G C T A
3.4 nm T A G C G C C G A T
1 nm C G T A C G G C C G A T
Figure 16.7 The double helix. A T
3 end A T
0.34 nm
5 end T A
(a)
Key features of DNA structure
(b) Partial chemical structure
Space-filling model
(c)

4. Structure of DNA An anti-parallel double helix
Form from two strands of nucleotides
Each nucleotide contains a phosphate group, a deoxyribose sugar, and a nitrogenous base
A, G = purines (two rings)
T, C = pyrimidines (one ring)
A bonds with T using two hydrogen bonds
G bonds with C using three hydrogen bonds

5. In Eukaryotes
DNA is carefully packaged into chromosomes for stability and control of gene transcription.

6. Nucleosome (10 nm in diameter)
Figure 16.22a
Nucleosome (10 nm in diameter)
DNA double helix (2 nm in diameter) H1
Histone tail
Figure Exploring: Chromatin Packing in a Eukaryotic Chromosome
Histones
Nucleosomes, or “beads on a string” (10-nm fiber)
DNA, the double helix
Histones

7. Replicated chromosome (1,400 nm)
Figure 16.22b
Chromatid (700 nm)
30-nm fiber
Loops
Scaffold
300-nm fiber
30-nm fiber
Figure Exploring: Chromatin Packing in a Eukaryotic Chromosome
Replicated chromosome (1,400 nm)
Looped domains (300-nm fiber)
Metaphase chromosome

8. Assignment:
Draw a DNA molecule (not in it’s helical shape, but as if it had been unwound).
Label 3’ and 5’ ends
Label each part of the nucleotides
Label which nitrogenous bases are pyrimidines and which are purines.
Color code!
Must contain a total of 12 bases (6 on each strand)