1. DNA, RNA, and Protein Synthesis
Chapter 10

2. history
DNA

3. DNA
1953 – James Watson and Francis Crick came up with the model of DNA

4. Franklin’s X-ray diffraction photograph of DNA
LE 16-6
Rosalind Franklin
Franklin’s X-ray diffraction
photograph of DNA

5. function
dna

6. DNA aka Deoxyribonucleic Acid
What does DNA do?
What do proteins do?
Stores and transmits genetic information that tells cells which proteins to make and when to make them.
Proteins, in turn, form the structural units of cells and help control chemical processes within cells.

7. structure
dna

8. What is DNA? DNA is a long molecule or “chain” of nucleotides.
A nucleotide is made up of 3 things:
Phosphate group
Deoxyribose (sugar)
Nitrogen base.

9. DNA Structure Made of repeating subunits called nucleotides.
There are 4 kinds of nitrogen bases.

10. DNA Structure
Four nitrogen bases
Adenine
Thymine
Guanine
Cytosine

11. Double-stranded Double Helix

12. Charagaff’s Rule Adenine = Thymine Guanine = Cytosine
This is how nitrogen bases pair up.
Adenine = Thymine
Guanine = Cytosine

13. DNA Structure Pyrimidines Purines 1 ring base Thymine and Cytosine
Adenine and Guanine

14. replication
dna

15. DNA Replication
DNA replication is the process by which DNA is copied in a cell before the cell divides by mitosis, meiosis, or binary fission.

16. DNA Replication When DNA is copied: the 2 strands or sides “unzip”
RNA brings new nucleotides into the nucleus to match the exposed nitrogen bases.

17. Steps of DNA Replication
Step 1- Unzip the DNA
Helicase enzymes separate DNA’s two chains of nucleotides

18. Steps of DNA Replication
Step 2- Fill in the missing bases
Enzymes called DNA polymerases bind to the separated chains.
One base (nucleotide) at a time, the enzyme constructs a new complementary chain of nucleotides

19. Steps of DNA Replication
Step 3- Complete and Pop Off
DNA polymerases finish replicating the DNA and fall off. There are now two identical DNA molecules

20. So one side “compliments”
DNA: Base Pairing
Each nucleotide in DNA preferentially pairs with its partner nucleotide on the opposite strand.
A pairs with T
C pairs with G
This structure of DNA is the physical basis for inheritance.
So one side “compliments”
the other.

21. DNA Replication Summary
During DNA replication, the DNA molecule separates into 2 strands, then produces 2 new complementary strands following the rules of base pairing.
Each strand of the double helix of DNA serves as a template, or model, for the new strand.
Check it out on page 201.

22. ACC GCT TTA GCC GAT TAC GAA
DNA Replication
Use the principle of base pairing to create this strand of DNA’s complimentary copy.
ACC GCT TTA GCC GAT TAC GAA
That’s easy!!
TGG
When you’re done with that example, create a new DNA strand for your partner to work on.

23. mechanism for inheritance
dna

24. DNA: Chromosomes
Genes are arranged along the long chains of DNA sequence, called chromosomes.

25. Incorrect
dna

26. Mutation
A change in the nucleotide sequence of a DNA molecule that affects genetic information.