What DNA molecule is the most stable?
DNA can adopt one of several different double helix structures: these are the A, B and Z forms of DNA. The B form, the most stable under cellular conditions, is considered the “standard” form; it’s the one you typically see in illustrations.
How much cytosine is in a DNA molecule?
Together, adenine and thymine compose 70% of the segment. This means that 30% of the section is composed of guanine-cytosine pairs. Since these two bases will be equal in quantity, 15% of the DNA section will be cytosine bases.
How many nucleotides are in a DNA molecule?
DNA molecules are composed of four nucleotides, and these nucleotides are linked together much like the words in a sentence. Together, all of the DNA “sentences” within a cell contain the instructions for building the proteins and other molecules that the cell needs to carry out its daily work.
What is the diameter of a DNA?
The diameter of the DNA helix is 2 nm and the vertical rise per base pair is 0.34 nm (Van Holde 1989). A DNA molecule is composed of two unbranched polynucleotide chains (strands) that wind about each other into a structure called a double helix, as illustrated in Figure 1.
Which DNA strand is more stable?
G-C base pairs have 3 hydrogen bonds, while A-T base pairs have two. Therefore, double-stranded DNA with a higher number of G-C base pairs will be more strongly bonded together, more stable, and will have a higher melting temperature.
Why is B form DNA most stable?
It is known that the stability of the double helical structure of B-DNA is supplied by the hydrogen bonds as proposed by Watson and Crick3 and by the stacking interactions.
Does DNA contain cytosine?
Cytosine is one of the four building blocks of DNA and RNA. So it’s one of the four nucleotides that’s present both in DNA, RNA, and each cytosine makes up part of the code. Cytosine has the unique property in that it binds in the double helix opposite a guanine, one of the other nucleotides.
What is the percentage of cytosine in A DNA molecule that has 18% thymine?
So, the correct answer is, ‘32%’.
How many nucleotides are in DNA and how do they differ?
There are four different DNA nucleotides, each defined by a specific nitrogenous base: adenine (often abbreviated “A” in science writing), thymine (abbreviated “T”), guanine (abbreviated “G”), and cytosine (abbreviated “C”) (Figure 2).
How many nucleotides make DNA and RNA?
Nucleotides are the units and the chemicals that are strung together to make nucleic acids, most notably RNA and DNA. And both of those are long chains of repeating nucleotides. There’s an A, C, G, and T in DNA, and in RNA there’s the same three nucleotides as DNA, and then the T is replaced with a uracil.
What is the diameter of two strands of DNA?
The diameter of the DNA double helix is 2 nm and is uniform throughout.
Why is the diameter of DNA constant?
The rules of complementarity keep the diameter of the double helix constant. Because A (2 rings) pairs with T (1 ring) and G (2 rings) pairs with C (1 ring), there is always a 2-ring base linked to a 1-ring base, so the width of the helix stays the same all throughout its length.
What’s the difference between 260 and 280 absorbance in DNA?
The difference of between 260 and 280 is good enough that scientists can use the A260nm/A280nm ratio (absorbance of 260/absorbance of 280) to validate purity of DNA samples (around 2.0 is considered pure).
Which is the wavelength of maximum absorption for DNA?
The wavelength of maximum absorption for both DNA and RNA is 260nm (λmax = 260nm) with a characteristic value for each base. You can refer this table which shows the spectral data of all the nucleotides at different pH values. The absorption properties of DNA can be used for detection, quantification and assessment of purity.
What kind of absorbance does a protein have?
Proteins that contain aromatic amino acid side chains (see below) will absorb at 280 nm, which isn’t that surprising now that you have seen the structure of the nucleobases above. “Why does DNA have a 260 nm absorbance peak whereas protein has a 280 nm absorbance peak?”
How to calculate the MW of a double stranded DNA molecule?
MW of a double-stranded DNA molecule = (# of base pairs) X (650 daltons/base pair) Moles of ends of a double-stranded DNA molecule = 2 X (grams of DNA) / (MW in daltons) Moles of ends generated by restriction endonuclease cleavage: a) circular DNA molecule: 2 X (moles of DNA) X (number of sites)