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Warm-Up. What is the purpose of DNA? Projects due Monday. DNA: Structure and Function. Objective. Students will demonstrate an understanding of DNA function and structure, and Chargaff’s rule. By the end of class today, you will be able to answer the following questions:
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Warm-Up • What is the purpose of DNA? • Projects due Monday
Objective • Students will demonstrate an understanding of DNA function and structure, and Chargaff’s rule. • By the end of class today, you will be able to answer the following questions: • What are the three parts of a DNA molecule? • Which DNA nucleotides pair with which?
First, Some Review • What is a nucleotide? • Any of the four pieces that make up DNA complete with the other parts. • The basic structural unit of DNA
What are the three parts of a DNA nucleotide? • You better know this • Nitrogenous base • 5 carbon sugar (ribose) • Phosphate backbone
What are the four nitrogenous bases in DNA? • Guanine • Adenine • Thymine • Cytosine • What’s the 5th one in RNA?
Pyrimidines and Purines • Which nitrogenous bases are pyrimidines? • Thymine (T) and Cytosine (C) • Which bases are purines? • Guanine (G) and Adenine (A)
Gangsters Are Pure G = guanine A = adenine P = purine
Mutation Question • G – C • A – T • T – A • G – C • C – G • T – A Using what you know about purines and pyrimidines, which nucleotide could replace the on you selected?
Chargaff’s Rule • Chargaff discovered base pairing. • Guanine always pairs with Cytosine • Adenine always pairs with Thymine
He’s Back • While doing his community service, Marty the Martian did a DNA analysis of a bacterium that you guys grew. He found that thymine was 18% of the bacterium’s DNA. How much of each nucleotide is present in that bacterium?