Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal)nucleus. It might consist of which of the following?
A) one-twelfth of the genes of the organism
B) two chromosomes, each with six chromatids
C) a single circular piece of DNA
D) two long strands of DNA plus proteins
E) two chromatids attached together at a centromere

Question

Quizplus · Accepted Answer

EChromatin is a complex of DNA and proteins (histones and others) found in the nucleus of eukaryotic cells. Its primary function is to package long DNA molecules into more compact, denser structures. This packaging allows the DNA to fit into the nucleus and plays important roles in regulating gene expression and DNA replication. Option D is correct because chromatin indeed consists of long strands of DNA wrapped around histone proteins. Option E is also correct because, during certain stages of the cell cycle, specifically in the S phase when DNA is replicated, chromatin can be seen as two sister chromatids (replicated chromosomes) attached at a centromere, representing the duplicated genome that will be separated during cell division. Options A, B, and C are incorrect for a eukaryotic nucleus: A) because the distribution of genes is not simply divided by the number of chromatin pieces, B) because chromosomes and chromatids are structured differently than described, and C) because eukaryotic DNA is linear and not circular (circular DNA is typically found in prokaryotes).

Suppose a Biologist Can Separate One of a Dozen Pieces