1. DNA vs. RNA

2. Discovery of DNA
Watson and Crick determined the shape of DNA and published that info in 1953
They based their work on the previous works of Rosalind Franklin and Chargraff
Franklin made X-Ray crystallography images of DNA
Chargraff said that the bases paired together

3. DNA
In the early 1950s, James Watson (American geneticist) and Francis Crick (British physicist) made a HUGE discovery
Prior evidence suggested that the structure of DNA might be a spiral or a helix, but no one knew for sure
However…

4. Nucleic Acids There are two types of nucleic acids
DNA = deoxyribonucleic acid
RNA = ribonucleic acid
Both types of nucleic acids are composed of building blocks called nucleotides (monomers)
Nucleotides have 3 parts:
Nitrogenous base
Sugar
Phosphate group
phosphate group
sugar
nitrogen-containing base

5. All About DNA Double helix Double = 2 strands Helix = twisted/winded
3 parts:
Nitrogenous bases
Adenine Thymine
Guanine Cytosine
Sugar = deoxyribose
Phosphate group

6. All About RNA Single helix Single = one strand Helix = twisted/winded
3 parts
Nitrogenous bases
Adenine Uracil
Guanine Cytosine
Sugar = ribose
Phosphate group

7. Molecule Shape/structure
Let’s compare the two!
DNA
RNA
Type of Bases
ATCG
AUCG
Type of Sugar
Deoxyribose
Ribose
Molecule Shape/structure
Double helix
Single helix

8. Complimentary Base-Pairings - DNA
The nitrogenous bases of DNA bond in the center of the helix. There are TWO pairs of complementary bases:
Adenine (A) will only pair with thymine (T); 2 hydrogen bonds connect them
Guanine (G) will only pair with cytosine (C); 3 hydrogen bonds connect them

9. Complimentary Base Pairings - RNA
When RNA bonds with DNA, each RNA base will only bond with one type of DNA base. These are still called complimentary bases.
Adenine (A) will only pair with uracil (U)
Guanine (G) will only pair with cytosine (C)

10. Let’s Practice!
Write the complimentary strand of DNA for the following 2 sequences of DNA:
A T G C A U G C T T A G T C C A
G C A T G G A A T C A C A G T T
Write the complimentary strand of RNA for the following 2 sequences of DNA:

11. Focus Questions What are the differences between DNA and RNA?
Include shape/structure, bases, sugar, location, purpose, and types.
How do bases pair in DNA?
How do bases pair between DNA and RNA?