Lecture_14_-_DNA_Structure_Analysis-1

Lecture_14_DNA_Str - Lecture 14 Lecture DNA Structure DNA Genetic Information Genetic In order for a molecule to serve as a reservoir of genetic

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Lecture 14 Lecture 14 DNA Structure DNA Structure
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Genetic Information Genetic Information In order for a molecule to serve as a reservoir of genetic information, it must have four main characteristics 1. Storage of information – the molecule must store and genetic information across generations 2. Replication – the molecule must be able to accurately transmit the genetic information across generations 3. Expression – the genetic information must be ‘expressed’ as the development of phenotypic characteristics in the individual 4. Evolution by Mutation – the genetic information must undergo changes to produce unique phenotypes that allow species to adapt to environmental changes
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Genetic Information Genetic Information Mendel proved in 1865 that some sort of genetic information existed that determined certain phenotypic characteristics in individuals and that this information was passed from one generation to the next. In 1871, a Swiss chemist, Friedrick Miescher, isolated an acid substance (DNA) in human white blood cells he called nuclein Studies of chromosomes and cell division around the turn of the century proved that the genetic information of Mendel’s studies was stored in the nucleus of cells in the nuclein which makes up the chromosomes
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Genetic Information Genetic Information Studies showed that this genetic information was passed from one generation to the next via the nuclein in the chromosomes Prior to the 1940’s it was widely believed that nuclein was made up of proteins The key component of nuclein, polynucleotide chains, was first discovered during the 1940’s The role of nucleic acids (DNA) in storing and transmitting genetic information was first documented in 1944 using bacterial transformation as a model
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Proof that Genetic Information is Proof that Genetic Information is Stored in DNA Stored in DNA Chromosomes are composed of two types of large organic molecules: proteins and nucleic acids (DNA and RNA) Several lines of indirect evidence suggest DNA, not proteins, store the genetic information in cells
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Indirect Proof that Genetic Indirect Proof that Genetic Information is Stored in DNA Information is Stored in DNA 1. Most of the DNA is located in the chromosomes, whereas RNA and proteins are located throughout the cell 2. A very precise correlation exists between the amount of DNA per cell and the number of chromosomes 3. The molecular composition of DNA is relatively the same in all cells of an organism whereas the composition of both RNA and proteins is highly variable from cell to cell 4. The genetic material must store and transmit the genetic information highly accurately from parent to offspring, therefore it must be highly stable like DNA, not variable like RNA or proteins 5. Mutagenesis – irradiating simple organisms such as fungi and yeast with UV light induces a number of mutations in the organisms. The UV wavelength that induces the most mutations is 260 nanometers; the same wavelength that is absorbed by DNA and RNA molecules but not by proteins
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This note was uploaded on 05/07/2011 for the course DARY 2072 taught by Professor Hay during the Spring '09 term at LSU.

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Lecture_14_DNA_Str - Lecture 14 Lecture DNA Structure DNA Genetic Information Genetic In order for a molecule to serve as a reservoir of genetic

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