Biology Chapter 16

Biology Chapter 16 - Chapter 16: The Molecular Basis of...

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Chapter 16: The Molecular Basis of Inheritance Evidence that DNA Can Transform Bacteria - Fredrick Griffith o Two strains of bacterium, Pathogenic (disease causing) and nonpathogenic (harmless) o Killed the pathogenic bacteria and mixed the cells remains with living nonpathogenic bacteria, some of them became pathogenic o Transformation: A change in genotype and phenotype due to the assimilation of external DNA by a cell Evidence that Viral DNA Can Program Cells - Bacteriophages: Virus that infects bacteria, also called a phage - Aklfred Hershey and Martha Chase showed that DNA is the genetic material of a phage known as T2 o T2: Virus composed of DNA and protein Reprogram its host cell to produce viruses o DNA of the virus is injected into the host cell during infection leaving the protein outside o Injected DNA provided genetic information that makes the cells produce new viral DNA and proteins Additional Evidence that DNA is the Genetic Material - Erwin Chargaff analyzed the base composition of DNA from a number of different organisms o (A)Adenine, (T) Thymine, (G) Guanine, (C) Cytosine Building a Structural Model of DNA Scientific Inquiry - Structure of a DNA strand: Each nucleotide (monomer) consists of a nitrogenous base (T, A, C or G), the sugar deoxyribose, and a phosphate group. - Phosphate of one nucleotide is attached to the sugar of the next backbone of alternating phosphates and sugars - The polynucleotide strand has directionality, from the 5’ end (phosphate group) to the 3’ end (-OH group) - 5’ and 3’ refer to the numbers assigned to the carbons in the sugar ring - Width of the helix is made up of two strands (double helix) o The two strands are held together by hydrogen bonds o The strands are antiparallel (they are oriented in opposite directions)
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This note was uploaded on 11/04/2010 for the course BIO 107 taught by Professor Abott during the Fall '09 term at UConn.

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Biology Chapter 16 - Chapter 16: The Molecular Basis of...

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