Text book Notes

Text book Notes - Chapter1GenesareDNA

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Chapter 1 - Genes are DNA Genome - hereditary nature of every living organism contains the complete set of hereditary information for any organism consist of the entire set of chromosomes for any particular organism. Comprises a series of DNA molecules, each of which contains many genes Nucleic Acid - long sequence that provides the information needed to construct the or- ganism Gene - sequence of DNA that produces another nucleic acid, RNA DNA has two strands of nucleic acid, whereas the RNA has only one strand The sequence of RNA is determined by the sequence of DNA gene - a sequence of DNA that codes for an RNA; in protein-coding genes, the RNA in turn codes for a protein. DNA --> RNA --> Protein Phage infection --> proved that DNA is the genetic material of viruses. When the DNA and protein components of bacteriophages are labeled with different radioactive iso- topes, only the DNA is transmitted to the progeny phages produced by infecting bacteria Phage T2 --> show DNA is the genetic material of DNA, Phage T2 virus infects the bacterium, then phage particles are added to bacteria, they adsorb to the outside sur- face, some material enters the bacterium, and then ~20 minutes later each bacterium burst open to release a large number of progeny phage. phage radio labeled either in DNA component ( 32 P) or in protein component ( 35 S). Infected bacteria agitated in blender, and two fractions were separated by centrifu- gation. One fraction contained the empty phage coats that were released from the surface of the bacteria; the other consisted of the infected bacteria themselves. experiment showed directly that only DNA of parent phages enter the bacteria and then becomes part of the progeny phages, which is exactly the pattern of inheritance expected of genetic material nucleoside consists of a purine or pyrimidine based linked to position 1 of a pentose sugar nucleotide consists of a nucleoside linked to a phosphate group on either the 5’ or 3’ position of the (deoxy)ribose basic building block of nucleic acids is the nucleotide components nitrogenous base purine or pyrimidine ring. Base is linked to position 1 on a pentose sugar by a glycosidic bond from N1 of pyrimidines or a N9 of purines. sugar phosphate sugar phosphate backbone consist of 5’-3’ phosphodiester linkage. The nitrogenous bases stick out from the backbone double helix x-ray diffraction showed DNA has the form of a regular helix, making complete turn every 34Å with a diameter of ~20Å. Since the distance between adjacent nucle- otides is 3.4Å, there must be 10 nucleotides per turn
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The density of DNA suggest that the helix must contain two polynucleotide chains. The constant diameter of the helix can be explained if the bases in each chain face
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This note was uploaded on 01/26/2009 for the course BIOLOGY 244 taught by Professor Palter during the Fall '05 term at Temple.

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Text book Notes - Chapter1GenesareDNA

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