Presentation on theme: "Set up Cornell Notes on pg. 67"— Presentation transcript:
1Set 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
2KEY CONCEPT DNA structure is the same in all organisms.
3DNA 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
4Thymine- T Adenine- A Guanine- G Cytosine-C The nitrogen containing bases are the only difference in the four nucleotides.BASESThymine- TAdenine- AGuanine- GCytosine-C
6Watson 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
7Watson 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.
8Nucleotides always pair in the same way. A pairs with TC pairs with Gthe helix has a uniform width.Ex: ladderCGTA
9The backbone is connected by covalent bonds. The bases are connected by hydrogen bonds.Hydrogen bondhydrogen bondcovalent bondbackboneBases (A,T,G,C)