1. Thursday 3/13 WARM UP!!!! 1. What is a nucleotide?
(USE CHAPTER 6 SECTION 1 TO find the answers!!!)
1. What is a nucleotide?
2. ___________ is a molecule that is present in all living cells that contains the information and determines the traits that a living thing inherits.

2. 1. What Does DNA Look Like?
The Pieces of the Puzzle-Scientists knew genes must be able to do two things
1) must be able to give instructions for building and maintaining cells.
2) It must be able to be copied each time a cell divides so each cell must contain identical genes.

3. 2. Nucleotides: The Subunits of DNA
1) DNA is made of subunits called nucleotides-a subunit that consists of a sugar, a phosphate, and a nitrogen base.
2) There are 4 different bases-adenine, thymine, guanine, and cytosine - each base has a different shape
3) adenine connects to thymine; guanine connects to cytosine

4. 3. Chargaff’s Rule
Rule-amount of adenine always equals thymine; the amount of
guanine always equals cytosine.
-this later helped scientists understand DNA

5. 4. Rosalind Franklin’s Discovery
Rosalind Franklin used X-ray diffraction to make images of DNA molecules. X rays are aimed at the DNA molecule. When an X ray hits a part of the molecule the ray bounces off. They saw it was spiral shaped.

6. 5. Watson and Crick’s Model-
After seeing Franklin’s images they decided it must look like a long, twisted ladder. They built a model of DNA which explained how it functions in the cell.

7. 6. DNA’s Double Structure-
Known as a double helix; sides always alternate between sugar and phosphate; the rungs of the ladder are always made of two bases.

8. 7. Making Copies of DNA
DNA-pairing of the bases allows cell to replicate

9. 8. How Copies of DNA are made
DNA splits down the middle where the bases meet
bases on each side of the molecule are used as a pattern for a new strand
as bases are exposed; complementary nucleotides are added to each side of the ladder.
DNA molecules are formed (half of each molecule is old and half is new)

10. 9. When Copies Are Made
DNA is copied every time a cell divides
Each gets a complete set of DNA
Unwinding, copying, and rewinding is done by proteins

11. PRACTICE What does DNA stand for?
If I gave you the Gene sequence TAACG, what would be the complementary side of the double helix? How about GCTAAGGC

12. PRACTICE ANSWERS Would be…ATTGC GCTAAGGC Would be CGATTCCG
DNA stands for: Deoxyribonucleic acid (You need to know this!)
The complementary bases for TAACG
Would be…ATTGC
GCTAAGGC
Would be CGATTCCG
WHY???? Because of Chargaff’s Rule… Adenine and Thymine & Cytosine and Guanine
REMEMBER THIS!!!(A&T… ALWAYS TOGETHER and C & G… THE WAY TO BE!)

13. SCIENCE TODAY
BE SURE YOUR Ch. 6 VOCAB IS FINISHED AND HAS BEEN CHECKED OFF BY ME!
YOUR OUTLINES ARE ALSO DUE!
I would like you to write your intro paragraph for me to look over
Complete Ch. 6 Notes (From Thurs 3/6)
THEN… work on HW… Ch. 6.1 Review