Adjacent pyrimidine bases in DNA form dimers with high efficiency after exposure to UV light. If these dimers are not repaired, skin cancers can result. Melanin is a natural sunscreen produced by melanocytes, a type of skin cell, when the skin is exposed to sunlight. Individuals who spend long periods developing a tan eventually acquire a thick and highly wrinkled skin. Such individuals are also at high risk for skin cancer. Can you explain, in general terms, why these phenomena are related?

Adjacent pyrimidine bases in DNA form dimers with high efficiency after exposure to UV light. If these dimers are not repaired, skin cancers can result. Melanin is a natural sunscreen produced by melanocytes, a type of skin cell, when the skin is exposed to sunlight. Individuals who spend long periods developing a tan eventually acquire a thick and highly wrinkled skin. Such individuals are also at high risk for skin cancer. Can you explain, in general terms, why these phenomena are related?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter8: The Structure, Replication, And Chromosomal Organization Of Dna

Section: Chapter Questions

Problem 12QP: DNA contains many hydrogen bonds. Are hydrogen bonds stronger or weaker than covalent bonds? What...

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What causes the change in the ability of DNA to absorb UV light when it is denatured? options: In denatured DNA, DNA double helix is disrupted, which causes the exposure of the deoxyribose and thus increases their absorbance of UV light In denatured DNA, DNA double helix is disrupted, which causes the exposure of the phosphate groups and thus increases their absorbance of UV light. In denatured DNA, DNA double helix is disrupted, which causes the exposure of the bases and thus increases their absorbance of UV light. all of the above are correct
In some organisms, UV-induced thymine dimers can be repaired by photoreactivation, in which energy from visible light is used to split the bonds forming the cyclobutane ring ? true or false Non-homologous end joining occurs when enzymes cut out a few nucleotides around a double strand DNA break, and then fuse the ends back together (right) true or false?
The ethidium bromide added to the agarose gels intercalates within the base pairs of the DNA double helix as it travels through the gel. Exposure to UV light causes the ethidium bromide to fluoresce, thus allowing for visualization of any DNA. How might this tendency of ethidium bromide to intercalate within the DNA double helix attribute to its carcinogenic properties in living organisms?
How important and useful to the cell is the ability of the DNA to assume various forms? Why are these various forms necessary?
The double helical structure of DNA is intrinsically unstable and easily dissociates to form two separate strands. Why? How does this affect the two key biological functions of chromosomal DNA? What would happen if the DNA helices were too stable?
The DNA of a skin sell and a muscle cell are identical. But the skin cell may contain the proteins collagen and keratin in high amount, which the muscle lacks (or has very little of), while the muscle cell may have large amounts of the proteins actin and myosin, which the skin cell lacks (or has very little of). Explain this apparent contradiction.
Refer to Figure 2 and compare this with the DNA model in Figure 1. a. In what ways are they similar? b. In what ways are they different? c. What is the biological significance of such differences? Why is the DNA referred to as the genetic material?
A subset of colorectal cancers is associated with mutations in the Mut genes which code for proteins involved in repairing DNA mismatches. How would mutations in the Mut genes affect the DNA of an individual?
DNA repair enzymes preferentially repair mis- matched bases on the newly synthesized DNA strand, using the old DNA strand as a template. If mismatches were instead repaired without regard for which strand served as template, would mismatch repair reduce repli- cation errors? Would such a mismatch repair system result in fewer mutations, more mutations, or the same number of mutations as there would have been without any repair at all? Explain your answers.
When UV light strikes DNA at a location where two thymines are side by side, what happens?
One common type of non-homologous end joining, to repair a double stranded break, occurs when enzymes cut out a few nucleotides around the break, and then fuse the ends back together true or false?
Using sickle cell as an example, give a detailed description of how the effects of a base substitution can be traced from DNA level to the level of the whole organism.