Fertilization of a frog egg triggers the resumption of meiosis by an increase in
a. ATP.
b. Ca2+.
c. cAMP.
d. PIP2.
Ans: b. Ca2+.
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Hydropathy analysis of a membrane protein's amino acid sequence predicts the protein's transmembrane segments and orientation in the membrane
It is necessary to confirm those predictions with experimental analysis. One experimental approach for plasma membrane proteins is to use the protease trypsin to digest extracellular domains of these proteins. (Trypsin is hydrophilic and cannot cross the plasma membrane to enter the cell.) When added to cells, trypsin digests the hydrophilic portions of plasma membrane proteins exposed outside the cell into small fragments but will not have access to transmembrane or cytosolic regions of proteins. Design a general experiment using trypsin and SDS-PAGE to address membrane protein association and orientation, and describe specific expected results that would be consistent with the following predicted membrane protein associations and orientations: a. a singlepass integral membrane protein with only its N-terminus exposed on the extracellular surface b. a singlepass integral membrane protein with only its C-terminus exposed on the extracellular surface c. a multipass integral membrane protein with only three hydrophilic loops exposed on the extracellular surface d. a fatty acylated protein e. a GPI-anchored protein What will be an ideal response?
What evolutionary event followed metabolic release of oxygen into the atmosphere and gave cells a significant selective advantage?
a. evolution of photosynthesis b. formation of multicellular organisms c. evolution of aerobic respiration mechanisms d. evolution of anaerobic metabolism e. oxidation
What name is given to the specific location of a gene on a chromosome?
A) locus B) phenotype C) genotype D) allele
Which of the following creates pluripotent stem cells without the need to destroy an embryo?
A) retrieval of stem cells from umbilical cord blood B) induced pluripotent stem cells C) retrieval of stem cells from adult bone marrow D) embryonic stem cell removal from unused embryos at fertility clinics