When a double-stranded DNA molecule is exposed tohigh temperature, the two strands separate, and themolecule loses its helical form. We say the DNA hasbeen denatured. (Denaturation also occurs whenDNA is exposed to acid or alkaline solutions.)a. Regions of the DNA that contain many A–T basepairs are the first to become denatured as the temperature of a DNA solution is raised. Thinkingabout the chemical structure of the DNA molecule, why do you think the A–T-rich regionsdenature first?b. If the temperature is lowered, the original DNAstrands can reanneal, or renature. In addition to thefull double-stranded molecules, some molecules ofthe type shown here are seen when the moleculesare examined under the electron microscope. Howcan you explain these structures?
Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
When a double-stranded DNA molecule is exposed to
high temperature, the two strands separate, and the
molecule loses its helical form. We say the DNA has
been denatured. (Denaturation also occurs when
DNA is exposed to acid or alkaline solutions.)
a. Regions of the DNA that contain many A–T base
pairs are the first to become denatured as the temperature of a DNA solution is raised. Thinking
about the chemical structure of the DNA molecule, why do you think the A–T-rich regions
denature first?
b. If the temperature is lowered, the original DNA
strands can reanneal, or renature. In addition to the
full double-stranded molecules, some molecules of
the type shown here are seen when the molecules
are examined under the electron microscope. How
can you explain these structures?
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