1. Information molecules
Nucleic acids:
Information molecules

2. Nucleic Acids Examples DNA DeoxyriboNucleic Acid RNA RiboNucleic Acid

3. Nucleic Acids Function: genetic material stores information genes
blueprint for building proteins
DNA  RNA  proteins
DNA
proteins

4. Nucleic acids 5 different nucleotides Building block = nucleotides
nucleotide – nucleotide – nucleotide – nucleotide
5 different nucleotides
different nitrogen bases
A, T, C, G, U
Nitrogen bases I’m the A,T,C,G or U part!
phosphate
sugar
N base

5. Nucleotide chains Nucleic acids nucleotides chained into a polymer DNA
phosphate
sugar
N base
Nucleic acids
nucleotides chained into a polymer
DNA
double-sided
double helix
A, C, G, T
RNA
single-sided
A, C, G, U
phosphate
sugar
N base
strong bonds
phosphate
sugar
N base
phosphate
sugar
N base
RNA

7. Deoxyribonucleic Acid
DNA Structure & Replication

8. Nitrogen Bases in DNA Four different types of bases 1. Adenine (A)
2. Guanine (G)
3. Cytosine (C)
4. Thymine (T)
Base paring rules:
Adenine binds to Thymine (A-T)
Cytosine binds to Guanine (C-G)

9. Example
ACTGCCGAAT
TGACGGCTTA

10. Copying DNA Replication copy DNA
2 strands of DNA helix are complementary
have one, can build other
when cells divide, they must duplicate DNA exactly for the new “daughter” cells
Why is this a good system?

11. Newly copied strands of DNA
DNA replication
Copying DNA
pairing of the bases allows each strand to serve as a pattern for a new strand
The greatest understatement in biology!
Newly copied strands of DNA

12. Two (of the many) enzymes needed for DNA replication
Helicase – breaks the hydrogen bonds between bases to unwind the DNA
DNA polymerases – bring new nucleotides into place, proofreads new strands as they form

14. First Glimpse of DNA
Franklin, trained as a chemist, was expert in deducing the structure of molecules by firing X-rays through them. Her images of DNA - disclosed without her knowledge - put Watson and Crick on the track towards the right structure. She went on to do pioneering work on the structures of viruses. .
Rosalind Franklin ( )

15. Rosalind Franklin and her X-ray diffraction photo of DNA
First Glimpse of DNA
Rosalind Franklin and her X-ray diffraction photo of DNA

16. The Double Helix
Watson and Crick (1953) discovered the structure of DNA to be a double helix or “spiral staircase” of two strands of nucleotides twisting around a central axis.
Names for DNA…double helix, twisted staircase

17. Watson and Crick … and others…
1953 | 1962