Presentation on theme: "Set up Cornell Notes on pg. 67"— Presentation transcript:
1 Set up Cornell Notes on pg. 67 8.2 Structure of DNA2.1 Atoms, Ions, and MoleculesSet up Cornell Notes on pg. 67Topic: 8.2 Structure of DNAEssential Question:Explain the base-pairing rules. How many types of nucleotides are there? How do they differ?Don’t forget to add it to your T.O.Contents!Explain the base-pairing rules. How many types of nucleotides are there? How do they differ?Key Concept:DNA structure is the same in all organisms
2 KEY CONCEPT DNA structure is the same in all organisms.
3 DNA is composed of four types of nucleotides. Each nucleotide has three parts.1. a phosphate group2. a deoxyribose sugar3. a nitrogen-containing basebasephosphate groupdeoxyribose (sugar)nitrogen-containingbase132backboneCovalent bonds
4 Thymine- T Adenine- A Guanine- G Cytosine-C The nitrogen containing bases are the only difference in the four nucleotides.BASESThymine- TAdenine- AGuanine- GCytosine-C
6 Watson and Crick determined the three-dimensional structure of DNA by building models. They realized that DNA is a double helixbackbone on the outsidebases on the inside.basesbackbone
7 Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff. Franklin’s x-ray images suggested that DNA was a double helix of even width.Chargaff’s rules stated that A=T and C=G.
8 Nucleotides always pair in the same way. A pairs with TC pairs with Gthe helix has a uniform width.Ex: ladderCGTA
9 The backbone is connected by covalent bonds. The bases are connected by hydrogen bonds.Hydrogen bondhydrogen bondcovalent bondbackboneBases (A,T,G,C)