Quiz 3 (Spring 2022)

Question 1

What are one structural similarity and one structural difference between A-type double-helical DNA and B-type DNA? Assume there are the same number of BP with the same sequence for both types of helices

Answer 1

One similarity is that anti-rotation is more stable, the difference is A-type has 10.5 nucleotides per rotation, B has 11.

Question 2

__________ is the wavelength of light (in nm) that nucleic acid can absorb.

Answer 2

260 nM

Question 3

__________ is the name of the specific component of a nucleotide that enables all nucleic acid to absorb the wavelength of light in part A.

Answer 3

Nucleobase

Question 4

Thermophiles are organisms that live in very hot locations such as near thermal vents or hot springs. Based on your knowledge of DNA, would you predict that the GC content of these organisms’ genomes would be higher or lower than the GC content from your genome? Explain your answer in chemical detail.

Answer 4

Higher, since 3 bonds hold G-C, it makes it harder for the helix to denature at high temperatures (higher Tm). In A-T only the H-bonds hold together, letting the heat have higher effect.

Question 5

Explain why trans-unsaturated fatty acids have a higher melting point than cis-unsaturated fatty acids.

Answer 5

Since the double bind is trans, it makes the molecule linear, allowing for tighter packing of the lipids, thus a higher melting point, Cis bends out, not as tightly packed