Which of these best describes cuchromatin in eukaryote cells? a \"chromatin fibe

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Which of these best describes cuchromatin in eukaryote cells? a "chromatin fiber" consisting of DNA and spaced beads of histone proteins The mixture of DNA and protein in the interphase nucleus The low density chromatin in a nucleus, enriched with expressed genes The high density chromatin in a nucleus, with very few expressed genes The vertebrate gene Pax 6 is needed for eye development. The Drosophila gene eyeless is also needed for eye development. Is Pax 6 homologous to eyeless? Maybe. If the genes are similar, in sequence and are in fact similar in function No, although they may work similarly, vertebrate genes are too different from insect genes to be homologous Yes. Because vertebrate eyes are homologous to insect eyes, their genes are also homologous Cells in the pancreas express a gene to make the digestive enzyme called trypsin. Suomach cells do not express this gene. Why is this gene expressed differently between these different cells? Pancreas cells have the trypsin gene, stomach cells do not Transcription factors in pancreas cells permit RNA polymerase to bind to the trypsin gene promoter. There are different transcription factors in stomach cells and these do not permit RNA polymerase to bind to the trypsin gene promoter. The enhancers in Pancreas cells permit RNA polymerase to bind to the trypsin gene promoter. There are different enhancers in stomach cells, and these do not permit RNA polymerase to bind to the trypsin gene promoter. Transcription factors in pancreas cells opens up the trypsin gene DNA rightarrow ssDNA, and this allows it to be expressed. The trypsin gene is kept as dsDNA by transcription factors in stomach cells, and so it is not expressed Darwin reasoned that animals on the Galapagos islands must have changed AFTER they arrived on the islands from nearby South America. Why was that? Fossils of Galapagos animals were found in South America saw them The animals had changed since early human explorers first saw them Darwin found that the species were new to science species were adapted to conditions on the islands, but the islands had not always been there since they were volcanoes Darwin found that among the different species of iguanas on the Galapagos islands, there were highly unusual iguanas that... could glide from branch to branch climbed trees and ate fruit had long necks for reaching up to browse vegetation had laterally flattened tails, adapted for swimming in the ocean In addition to Darwin, who else had developed a theory of evolution by natural selection? H. Beagle Charles Lyell Stephen Jay Gould Alfred Wallace Aristotle

Explanation / Answer

27 (A)

A homologous gene is a gene inherited in two species by a common ancestor. Pax 6 and eyeless with similar sequence and function in different species constitute homoglogous genes.

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