Chapter 10

Chapter 10 - a W and C originally thought that there should...

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a. W and C originally thought that there should be 3 H bonds, however they soon realized this is not possible. b. G always pairs with C by 3 hydrogen bonds a. It takes a little more energy to break this bond b. Note: When Watson and Crick put there model parallel, these H bonding distances where not matched up to make a consistent diameter Because of the chemical nature of DNA, you can denature and then renature it with heat, unlike a protein. Because of the base pairing, they perfectly come together because of the attraction of the bases. An increase in pH can also have the same effect. Chapter 10 DNA Replication In order for cells to be able to survive, they must be able to replicate there DNA and pass it on. The fact of base pairing immediately jumped out at Watson and Crick. If you have one strand you can automatically determine the other stand. They did not know the mechanism, however, they put a quote in their paper about DNA replication, so whoever figured it out would have to cite Watson and Crick. “It has not escaped our notice that the specific pairing we have postulated immediately sugge sts a possible copying mechanism for the genetic material”. -James Watson, 1953. I. DNA Replication A. DNA is replicated by enzymes known as: DNA dependent DNA polymerases a. The require a DNA template because they require a DNA template 1. Replication is semiconservative 2. Meselson Stahl experiment
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a. These men where trying to figure out how DNA was replicated. That they time there were three prosposals: i. Conservative 1. The two strands separate and each strand serves as the template for a new strand of DNA. After this replication is finished the original parents strands get back together and the two daughter strands come together and form double stranded DNA 2. This model is a little messy ii. Semi-conservative 1. The parent DNA seperates and then DNA polymerase comes in an adds base pairs iii. Dispersive 1. Newly replicated DNA contains portions of parent and daughter DNA mixed together They grew E. coli in growth media, with the sole N 15 source. N 14 is the most commonly force of N. As they bacteria where making the bases, everything was labeled with a heavy isotope of N. Then they shifted the growth media to with N
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Chapter 10 - a W and C originally thought that there should...

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