1. Replication Makin’ copies

2. Discovering the structure of DNA
DNA = Deoxyribose nucleic acid
Made out of sugars (deoxyribose), phosphates
and nitrogen bases

3. DNA
1. Double Stranded Helix
2. Hydrogen Bonds between Nitrogenous Base Pairs
3. Base Pairs are
Adenine-Thymine
and
Guanine-Cytosine

5. Discovering the structure of DNA
Rosalind Franklin’s DNA image
“Chargoff’s rule”
A = T & C = G

6. Discovering the structure of DNA
Structure was discovered in 1953 by James
Watson and Francis Crick

7. Cell division and DNA replication
Cells divide
Growth, Repair, Replacement
Before cells divide they have to double cell
structures, organelles and their genetic
information

8. DNA replication

9. Replication
The duplication of DNA which occurs during the S phase of Interphase.
1 Strand  2 Complementary Strands
DNA Polymerase

12. One More Time!

13. DNA Structure thymine adenine cytosine guanine phosphate
Hydrogen bond
(H-bonds)
DNA Structure
thymine
adenine
cytosine
guanine
phosphate
deoxyribose sugar
Sugar / phosphate “strand”
Nitrogenous base “rung”
DNA nucleotide
RNA nucleotide
Deoxyribose sugar
ribose sugar
Nitrogenous base
(guanine)
Nitrogenous base
(uracil)
phosphate
phosphate

14. DNA Replication Step 1: Hydrogen bonds between complimentary
bases break
DNA “unzips”

15. DNA Replication
Step 2: DNA strands
pull apart from each other

16. DNA Replication Step 3: DNA nucleotides in the cell
match up with each side of the
“unzipped” DNA
each “unzipped’ strands forms a
template for a new strand

17. DNA Replication Step 4: Each “old’ strand forms a template for a
“new” strand
two identical DNA
molecules form
Semiconservative Replication
“new” strand, identical
sequence to the original
Link with labels
“old” (original) strand