LECTURE 06 DNA Structure & Function

LECTURE 06 DNA - 2:010 Principles of Biology Lecture 6 DNA the Genetic Material It should be apparent to all of us that we look more like our

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2:010 Principles of Biology Lecture 6 DNA the Genetic Material It should be apparent to all of us that we look more like our parents than any other people. There is some information that is passed on from one generation to the next that determines the physical characteristics of the next generation. This was first scientifically studied by Gregor Mendel in the 19 th Century and his work will be studied in more detail next semester. It was in 1883 that this information that influences what you will look like was proposed to be of a molecular nature rather than some mysterious invisible force. These molecules were called genetic material. The functions of this genetic material allow it to: Serve as a blueprint for all the steps in the construction of a living organism. It determines how a fertilized egg turns into an embryo, which in turn develops into a new-born which matures into an adult. Regulate the mechanisms that enable the organism to survive in a changing environment. This genetic material must have certain properties that can serve as criteria for determining its identity. These include: Its containing the information needed to perform the functions. Its transmission from parent to offspring and from cell to cell within a multicellular organism growing by cell division. Its replication must be accurate in order for transmission to occur. Its expressing variation to account for the differences among different species as well as the differences among individuals of the same species. Experiments done by Morgan in the beginning of the 20 th C. showed that these genes are present on the chromosomes in the nucleus of the cell. Chromosome means colored body referring to the ease with which these structures are stained with colored dyes. 1
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It is seen that the structure of these chromosomes changes during the life cycle of a cell. This will be covered in more detail in the lecture on cell division. Chromosomes are complexes of protein and DNA. Each chromosome has one very long molecule of DNA and many different proteins. You are already familiar with the structure and function of proteins. What about DNA? DNA is a nucleic acid as is RNA. The name comes from the discovery of a phosphorous containing substance located in the cell nucleus, It is an acid because it releases H + when dissolved in an aqueous solution of neutral pH. It has a net negative charge. DNA is a very large macromolecule or polymer whose building blocks are nucleotides. It is a polynucleotide . Lets look at the structure of a nucleotide. It has 3 main chemical components 1. Sugar – in this case a 5 carbon sugar (pentose) that is missing oxygen on the carbon in the number 2 position. This sugar is deoxyribose. This is where we get the D 2
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in DNA (deoxyribonucleic acid) We will later talk about molecules that contain the sugar, ribose, with oxygen on all carbons. This contributes to the structure of RNA (Ribonucleic acid). 2. The nitrogenous base is covalently attached to the sugar.
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This note was uploaded on 03/30/2008 for the course BIO 2:010 taught by Professor Denburg during the Spring '08 term at University of Iowa.

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LECTURE 06 DNA - 2:010 Principles of Biology Lecture 6 DNA the Genetic Material It should be apparent to all of us that we look more like our

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