Which of the following methods can be used to isolate DNA（）
A. Salt extraction
B. Cesium chloride density gradient centrifugation
C. Electrophoresis
D. Heating precipitation
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Regarding the tertiary structure of DNA, which of the following statements are correct（）
A. The tertiary structure of A DNA is a supercoiled structure formed on the basis of secondary structure
B. The double-stranded DNA of B prokaryotic DNA is entangled in histones to form nucleosomes
C. Histones involved in the formation of nucleosomes include five subunits: H1, H2A, H2B, H3, and H4
D. The formation of supercoiled structure compressed the length of DNA in the nucleus by nearly ten thousands time
Which of the following statements about the Watson-Crick DNA double helix structure model is wrong（）
A. The direction of the two single chains is anti-parallel
Base A and G pair
Covalent bonding between bases
D. The pentose phosphate backbone is located inside the double helix
The factors that affect the Tm value are（）
A. The longer the nucleic acid molecule under certain conditions, the larger the Tm value
B. The content of G and C in DNA is high, the Tm value is high
C. Solution has high ionic strength, Tm value is high
D. High content of A and T in DNA, high Tm value
After double-stranded DNA thermal denaturation（）
A. Decrease in viscosity
B. Decrease in sedimentation coefficient
C. Decrease in buoyancy density
Decrease in UV absorption
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