Presentation on theme: "Thursday 3/13 WARM UP!!!! 1. What is a nucleotide?"— Presentation transcript:
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 things1) 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 shape3) adenine connects to thymine; guanine connects to cytosine
4 3. Chargaff’s RuleRule-amount of adenine always equals thymine; the amount ofguanine 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 DNADNA-pairing of the bases allows cell to replicate
9 8. How Copies of DNA are made DNA splits down the middle where the bases meetbases on each side of the molecule are used as a pattern for a new strandas 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 MadeDNA is copied every time a cell dividesEach gets a complete set of DNAUnwinding, 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 TAACGWould be…ATTGCGCTAAGGCWould be CGATTCCGWHY???? Because of Chargaff’s Rule… Adenine and Thymine & Cytosine and GuanineREMEMBER THIS!!!(A&T… ALWAYS TOGETHER and C & G… THE WAY TO BE!)
13 SCIENCE TODAYBE 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 overComplete Ch. 6 Notes (From Thurs 3/6)THEN… work on HW… Ch. 6.1 Review