Prokaryote means before the nucleus, but what general feature co uld prokaryotes also be said to lack? What will be an ideal response?
Prokaryotes generally lack any organelles and are poorly compartmentalized.
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The middle layer of the leaf is composed of the
a. lower epidermis. b. mesophyll. c. upper epidermis. d. waxy layer
Living members of ____ are often the dominant land plants in cool temperate zones. Among other products, they are
important sources of lumber, paper pulp, resins, and turpentine.
a. lycophytes b. ferns c. gymnosperms d. bryophytes
e. angiospermsWhy does meiosis promote genetic variability?
A. Meiosis undergoes one cell division producing diploid cells. B. Meiosis undergoes one cell division producing haploid cells. C. Meiosis undergoes two cell division producing diploid cells. D. Meiosis undergoes two cell division producing haploid cells.
You are interested in understanding how the brain works, and are using the fruit fly Drosophila as a model system to study brain development. You perform a microarray analysis to try to determine genes expressed in the fly brain
For your microarray experiment, you first prepare cDNA from fly brains and label it with a red fluorochrome. Then you isolate cDNA from whole flies and label it with a green fluorochrome. Next you hybridize these cDNA populations to a microarray containing the Drosophila genes. From this you obtain a list of genes that are specifically enriched in the brain (those that show up as a red spot on the microarray). You are disappointed because your favorite fly gene, tubby, does not appear on this list, even though you have repeated the microarray experiment 10 times and did not encounter any technical difficulties. The reason you thought tubby would appear on this list is that you believe tubby is important for brain development, because flies mutant in tubby have no brains. Not to be discouraged, you perform in situ analysis using the tubby DNA as a probe, and see that it is expressed at high levels in the fly brain of normal flies but not expressed in animals lacking the tubby gene. Why do you think tubby did not show up as a gene specifically enriched in the brain in your microarray experiment?