1. Organism A has a DNA length of 100 b.p.; organism B has a linker DNA length of 60 b.p. Which of the statements about their 10 nm fibers will be TRUE?
A. organism A will have larger "beads" than organism B
B. organism A will have longer "strings" than organism B
C. organism B will have larger "beads" than organism B
D. organism B will have longer "strings" than organism B
E. their fibers will look the same
To answer this question, we need to understand how DNA is structured in the 10 nm fibers.
DNA in the 10 nm fiber form is organized into repeating units called nucleosomes. Each nucleosome consists of DNA wrapped around a protein cluster known as a histone octamer.
Let's analyze the given information:
- Organism A has a DNA length of 100 base pairs (b.p.).
- Organism B has a linker DNA length of 60 b.p.
Based on this information, we can conclude that organism A has a longer DNA segment than organism B.
Now let's evaluate the options:
A. organism A will have larger "beads" than organism B
- True. Since organism A has a longer DNA length, it will have more nucleosomes and hence larger "beads" (histone octamers) compared to organism B.
B. organism A will have longer "strings" than organism B
- False. The length of the "strings" between nucleosomes (linker DNA) is not specified for organism A. So we cannot determine if organism A will have longer "strings" than organism B based on the given information.
C. organism B will have larger "beads" than organism B
- False. This statement is contradictory.
D. organism B will have longer "strings" than organism B
- False. Organism B is specifically mentioned to have a linker DNA length of 60 b.p., which means organism B has shorter "strings" between nucleosomes compared to organism A (assuming no linker DNA is present in organism A). Therefore, organism B will have shorter "strings" rather than longer.
E. their fibers will look the same
- False. The given information clearly states that organism A has a longer DNA length than organism B. This implies that their fibers will not look the same.
Based on the above analysis, the correct answer would be A. Organism A will have larger "beads" (histone octamers) than organism B.