Fig 9-1 Figure: 09-01 Caption: Simplified view of information flow involving DNA, RNA, and proteins within cells.

Fig 9-2 Figure: 09-02 Caption: Diagrammatic depiction of Levene’s proposed tetranucleotide containing one molecule each of the four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C). Each block represents a nucleotide. Other potential sequences of four nucleotides are possible.

Fig 9-3 Figure: 09-03 Caption: Griffith’s transformation experiment. The photographs show bacterial colonies containing cells with capsules (type IIIS) and without capsules (type IIR).

Fig 9-4 Figure: 09-04 Caption: Summary of Avery, MacLeod, and McCarty’s experiment, which demonstrated that DNA is the transforming principle.

Fig 9-5 Figure: 09-05_a Caption: Life cycle of a T-even bacteriophage. The electron micrograph shows an E. coli cell during infection by numerous phages.

Fig 9-5 Figure: 09-05_b Caption: Life cycle of a T-even bacteriophage. The electron micrograph shows an E. coli cell during infection by numerous phages.

Fig 9-6 Figure: 09-06 Caption: Summary of the Hershey–Chase experiment demonstrating that DNA, and not protein, is responsible for directing the reproduction of phage T2 during the infection of E. coli.

Fig 9-7 Figure: 09-07 Caption: Comparison of the action spectrum (which determines the most effective mutagenic UV wavelength) and the absorption spectrum (which shows the range of wavelength where nucleic acids and proteins absorb UV light).

Fig 9-9 Figure: 09-09 Caption: (a) Chemical structures of the pyrimidines and purines that serve as the nitrogenous bases in RNA and DNA. The nomenclature for numbering carbon and nitrogen atoms making up the two bases is shown within the structures shown on the left. (b) Chemical ring structures of ribose and 2-deoxyribose, which serve as the pentose sugars in RNA and DNA, respectively.

Fig 9-10 Figure: 09-10 Caption: Structures and names of the nucleosides and nucleotides of RNA and DNA.

Fig 9-11 deoxy deoxy Figure: 09-11 Caption: Basic structures of nucleoside diphosphates and triphosphates, as illustrated by thymidine diphosphate and adenosine triphosphate. deoxy deoxy

Fig 9-12 Figure: 09-12 Caption: (a) Linkage of two nucleotides by the formation of a  phosphodiester bond, producing a dinucleotide. (b) Shorthand notation for a polynucleotide chain.

Fig 9-14 Figure: 09-14 Caption: (a) The DNA double helix as proposed by Watson and Crick. The ribbonlike strands constitute the sugar-phosphate backbones, and the horizontal rungs constitute the nitrogenous base pairs, of which there are 10 per complete turn. The major and minor grooves are apparent. The solid vertical bar represents the central axis. (b) A detailed view depicting the bases, sugars, phophates, and hydrogen bonds of the helix. (c) A demonstration of the antiparallel nature of the helix and the horizontal stacking of the bases.

Fig 9-15 Figure: 09-15 Caption: The right- and left-handed helical forms of DNA. Note that they are mirror images of one another.

Fig 9-16 Figure: 09-16 Caption: Ball-and-stick models of A\T and G#C base pairs. The dashes (– – –) represent the hydrogen bonds that form between bases.

Fig 9-17 Figure: 09-17 Caption: The top half of the figure shows computer-generated space-filling models of B-DNA (left), A-DNA (center), and Z-DNA (right). Below is an artist’s depiction illustrating the orientation of the base pairs of B-DNA and A-DNA. (Note that in B-DNA the base pairs are perpendicular to the helix, while they are tilted and pulled away from the helix in A-DNA.)

Fig 9-18 Figure: 09-18_a Caption: Separation of a mixture of two types of nucleic acid by gradient centrifugation. To fractionate the gradient, successive samples are eluted from the bottom of the tube. Each is measured for absorbance of ultraviolet light at 260 nm, producing a profile of the sample in graphic form.

Fig 9-18 Figure: 09-18_b Caption: Separation of a mixture of two types of nucleic acid by gradient centrifugation. To fractionate the gradient, successive samples are eluted from the bottom of the tube. Each is measured for absorbance of ultraviolet light at 260 nm, producing a profile of the sample in graphic form.

Fig 9-18 Figure: 09-18_c Caption: Separation of a mixture of two types of nucleic acid by gradient centrifugation. To fractionate the gradient, successive samples are eluted from the bottom of the tube. Each is measured for absorbance of ultraviolet light at 260 nm, producing a profile of the sample in graphic form.

Fig 9-19 Figure: 09-19 Caption: Percentage of guanine–cytosine G#C base pairs in DNA, plotted against buoyant density for a variety of microorganisms.

Fig 9-20 Figure: 09-20 Caption: Increase in UV absorption vs. temperature (the hyperchromic effect) for two DNA molecules with different GC contents. The molecule with a melting point  of  has a greater GC content than the molecule with a  of 

Fig 9-21 Can be a strand of DNA Figure: 09-21 Caption: Diagrammatic representation of the process of molecular hybridization between DNA fragments and RNA that has been transcribed on one of the single-stranded fragments.

Fig 9-23 Figure: 09-23 Caption: The ideal time course for reassociation of DNA (C/C0) when, at time zero, all DNA consists of unique fragments of single-stranded complements. Note that the abscissa (C0t) is plotted logarithmically.

C 1 ___ = ________ C0 1 + k C0t

Fig 9-24 Figure: 09-24 Caption: The reassociation rates (C/C0) of DNA derived from phage MS2, phage T4, and E. coli. The genome of T4 is larger than MS2 and that of E. coli is larger than T4.

Fig 9-25 Figure: 09-25 Caption: Comparison of C0T1/2 and genome size for phage T4, E. coli, calf, and salamander.

Fig 9-26 Figure: 09-26 Caption: The  curve of calf thymus DNA compared with E. coli. The repetitive fraction of calf DNA reassociates more quickly than that of E. coli, while the more complex unique calf DNA takes longer to reassociate than that of E. coli.

Fig 9-27 Figure: 09-27 Caption: Electrophoretic separation of a mixture of DNA fragments that vary in length. The photograph shows an agarose gel with DNA bands corresponding to the diagram.