Describe the mechanism by which heterochromatin can spread, once it has been established in one region of the chromosome
What will be an ideal response?
Once the initial H3 lysine 9 methylation is established on core histone octamers in one region, the modification attracts a specific set of proteins and other histone-methylating enzymes. These enzymes create the same modification on adjacent histone octamers, which continue to recruit more heterochromatin-specific proteins and enzymes, creating a wave of heterochromatin spreading along the chromosome.
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Amoebozoans can be multicellular during part of their lifecycle through:
A. Amoebozoans are never multicellular. B. binary fission. C. symbiosis. D. aggregation of cells.
Which of the following white blood cells are implicated in transplanted organ rejection?
a. eosinophils b. macrophages c. T cells d. natural killer cells
The structure labeled "4" in the figure is a(n) ____
a. asexual spore b. haploid spore
c. zygospore d. gamete e. spore sac
Which statement regarding DNA packing is false?
A) A nucleosome consists of DNA wound around a protein core of eight histone molecules. B) DNA packing tends to promote gene expression. C) Highly compacted chromatin is generally not expressed at all. D) Prokaryotes have proteins analogous to histones.