Answer to Question #220476 in General Chemistry for Dagmawi Minilik

Question

1. What is biological opportunism and give one example?

2. A bacteriophage has A-form DNA. A deletion mutant has a length of 10.4 μm instead of 15 μm. How many base pairs are missing from this mutant?

3. Explain how G-quadruplex binding molecules could be developed into potential anticancer drugs.

4. What are the percentage of all the bases (A, C, & G) in DNA that is 20% thymine?

5. The base sequence of one of the strands of a 20-bp duplex DNA is 5'-TCCGTTCGACGGTACATC-3' write the base sequence of its complementary strand.

Answer 1

Opportunist micro-organisms (such as bacteria, viruses, fungi, and protozoa) are ones that, when they invade the host organism, can cause infection in the host organism, but cause real disease only if the natural defenses, resistance or immune system of the host organism are lowered (see opportunistic infection).

Base pairs $=\frac{15}{10.4}= 1.44 μm$

G-quadruplex structures are formed by stacked guanine tetrads (G-tetrads) . Within a G-tetrad, four guanine bases are arranged in a square plane with Hoogsteen hydrogen bonding, instead of the Watson-Crick hydrogen bonding of B-DNA (Figure 1(a, b)). G-quadruplex structures form readily in solution in the presence of either Na⁺ or K⁺ [23]. These physiologically relevant monovalent cations are required to stabilize G-quadruplex structures by positioning between the G-tetrad planes in coordination with the O6 atoms of the tetrad guanines . G-quadruplexes can be monomeric or multimeric (e.g., dimeric or tetrameric) (Figure 1(c, d)). Within the G-tetrad, guanine residues may adopt either syn or anti-glycosidic conformation [8] . Adjacent DNA strands in a G-quadruplex can have the same (parallel) or opposite (anti-parallel) orientation ; guanines of parallel DNA strands will adopt the same, generally anti, conformation, whereas guanines of anti-parallel strands will adopt opposing conformations [8] .

If you have 20% of adenine than you have 20% of thymine, because the amount of adenine and thymine is equal. 20% plus 20% is 40% of adennine and thymine. From 100% DNA bases subtract 40% and you will get 60%.