1. DNA Learning Goal: To learn about the structure of DNA.
Success Criteria:
I know I am succeeding when I can…
explain that DNA stores and transmits genetic information from parent to offspring
explain the structure of DNA
explain how complementary bases form pairs
determine the nucleotide base sequence for one strand, from its complementary strand
model the structure of DNA

2. DNA
deoxyribonucleic acid (DNA) is the molecule that stores and transmits genetic information from parents to offspring

3. The Chemical Composition of DNA
DNA is composed of building blocks called nucleotides
Nucleotides are made up of three different molecules:
a nitrogenous base
a sugar (deoxyribose)
a phosphate group
*Note:* DNA has a negative charge because of the phosphate ions in its backbone

4. The Chemical Composition of DNA
There are four different bases that make up DNA nucleotides:
adenine (A)
guanine (G)
cytosine (C)
thymine (T)

5. The Structure of the DNA Molecule
The chemical backbone of a DNA strand is made up of alternating phosphate groups and pentose sugars.
Attached to this backbone are nitrogenous bases: adenine, guanine, cytosine, and thymine

6. The Structure of the DNA Molecule Cont’d…
The bases of one strand are paired with the bases of the other strand in the following arrangement:
Thymine (T) is always bonded to adenine (A)
Cytosine (C) is always bonded to guanine (G)
This is called base pairing

7. The Chemical Composition of DNA
Since the bases are complementary, if we know the nucleotide base sequence for one strand, we can determine it for the other strand
For example, the complementary base sequence for ATGGCCATC would be
TACCGGTAG

8. Homework
read pages in your text
answer 6.1 questions #1-5