Presentation on theme: "8.2 Structure of DNA Set up Cornell Notes on pg. 67 Topic: 8.2 Structure of DNA Essential Question: Explain the base-pairing rules. How many types of nucleotides."— Presentation transcript:
8.2 Structure of DNA Set up Cornell Notes on pg. 67 Topic: 8.2 Structure of DNA Essential 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! 2.1 Atoms, Ions, and Molecules Explain the base-pairing rules. How many types of nucleotides are there? How do they differ? 8.2 Structure of DNA Key Concept:DNA structure is the same in all organisms
8.2 Structure of DNA KEY CONCEPT DNA structure is the same in all organisms.
8.2 Structure of DNA DNA is composed of four types of nucleotides. Each nucleotide has three parts. 1. a phosphate group 2. a deoxyribose sugar 3. a nitrogen-containing base phosphate group deoxyribose (sugar) nitrogen-containing base Covalent bonds base backbone
8.2 Structure of DNA The nitrogen containing bases are the only difference in the four nucleotides. Thymine- T Adenine- A Guanine- G Cytosine-C BASES
8.2 Structure of DNA
Watson and Crick determined the three-dimensional structure of DNA by building models. They realized that DNA is a double helix –backbone on the outside –bases on the inside. backbone bases
8.2 Structure of DNA 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.
8.2 Structure of DNA T A C G Nucleotides always pair in the same way. the helix has a uniform width. –Ex: ladder – A pairs with T – C pairs with G
8.2 Structure of DNA The backbone is connected by covalent bonds. hydrogen bondcovalent bond The bases are connected by hydrogen bonds. backbone Hydrogen bond Bases (A,T,G,C)
8.2 Structure of DNA A T C C G A T G A T GC
GATTACAATCGATCGAT CTAATGTTAGCTAGCTA TAGGACTACTAGTCGTA ATCCTGATGATCAGCAT Using the base pairing rules- complete the DNA strand:
8.2 Structure of DNA Adenine (A) = Green Thymine (T) = Pink Cytosine (C) = Yellow Guanine (G) = Orange Have Your DNA & Eat It Too * I need to check your work before you eat the DNA!!!!!