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12-1 DNA . Objectives. Summarize the relationship between genes and DNA. Describe the overall structure of the DNA molecule. The red box indicates something important that you will want to write down. . What’s So Special About DNA?.
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Objectives • Summarize the relationship between genes and DNA. • Describe the overall structure of the DNA molecule. The red box indicates something important that you will want to write down.
What’s So Special About DNA? DNA is actually one of the most boring molecules in the human body: • It’s made of only four building blocks. • Worse yet it just sits in the nucleus. • It does not build cell. • It does not catalyze any reactions. So WHAT’S SO SPECIAL ABOUT DNA? • Amazing ability to store and copy information.
How Can DNA Copy & Store Information? Key Properties of DNA: • Double stranded molecule. • Held together by base pairs that compliment each other. • Pairs are created following simple rules.
The Components and Structure of DNA • Scientists knew genes were made of DNA (pg. 288). • The did not know how DNA… • Carries information from one generation to the next. • Determines the heritable characteristics of an organism. • Is copied.
The Components and Structure of DNA • DNA is a molecule made up of nucleotides. • Nucleotides have three parts: • Phosphate group • Deoxyribose (sugar molecule) • Nitrogenous base (four types) Backbone
The Components and Structure of DNA Nitrogenous Bases • Adenine • Guanine • Thymine • Cytosine • Scientists were amazed to find how many different combinations the nitrogenous bases could make.
The components and structure Nitrogenous Bases • Adenine (purine) • Guanine (purine) • Thymine (pyrimidine) • Cytosine (pyrimidine)
Watson & Crick • During the mid 1900s, scientists were trying to find the shape of the DNA molecule. • In 1953 James Watson and Francis Crick discovered the double helix shape of the DNA molecule.
Homework Chapter 12 Reviews Pg. 294, 2-4 Pg. 299, 1-6 OMIT #4 Pg. 306, 1-5 Pg. 308, 1-4
Watson & Crick • Two strands were wrapped around each other. • Formed “double helix” shape. • Looks like a twisted ladder.
Watson & Crick • Watson & Crick did not know what held the helix together. • Hydrogen bonds hold both strands together. • Bonds would form between certain base pairs (base pairing): • Adenine = Thymine • Cytosine = Guanine
Closure • Summarize the relationship between genes and DNA. • Describe the overall structure of the DNA molecule. • We’re going to review to see if you can do the objectives by answering questions on the whiteboards.
Questions • What were the names of the scientists that discovered the shape of the DNA molecule? • What is the shape of the DNA molecule? • What are the three parts of the DNA molecule? • Name the four nitrogeneous bases. • What is the difference between purines and pyrimidines? • Write the corresponding DNA strand that goes with the following groups: • TCGAGCCTA • ACCGATTAC
Homework Chapter 12 Reviews Pg. 294, 2-4 Pg. 299, 1-6 OMIT #4 Pg. 306, 1-5 Pg. 308, 1-4