Membrane-like structures form when proteins or lipids are mixed with water. They serve as a model
for __________, which may have preceded cells. Fill in the blank(s) with the appropriate word(s).
protocells
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The single-celled yeast, Saccharomyces cerevisiae, was used to construct the first eukaryotic artificial chromosome. This was a significant achievement because
A) yeast centromeres are identical to human centromeres. B) it defined chromosomal regions that serve as centromeres and origins of replication in yeast. C) it revealed the rate of DNA replication in yeast. D) it demonstrated that some yeast genes are not essential. E) it defined the chromosomal region with the TRP+ gene for tryptophan synthesis in yeast.
In adaptive immune responses, which cell type is capable of acting as an antigen-presenting cell?
a. T cell b. monocyte c. eosinophil d. B cell e. basophil
Which of the following will occur in meiosis but not in mitosis?
a)metaphase b)cytokinesis c)crossing over d)DNA replication e)chromosome condensation
The deamination of cytosine generates a uracil base. This is a naturally occurring nucleic acid base, and so does not represent a DNA lesion caused by damage due to chemicals or irradiation
Why is this base recognized as "foreign" and why is it important for cells to have a mechanism to recognize and remove uracil when it is found in the DNA duplex?