Compare and contrast the chemical composition and structure of the cytoplasmic membranes found in Bacteria and Archaea. What is the advantage of the archaeal membranes in relationship to the types of environments many archaea inhabit?
What will be an ideal response?
Answer: Bacterial cytoplasmic membranes contain fatty acids with ester linkages that always form a phospholipid bilayer that is highly fluid. Archaeal cytoplasmic membranes contain glycerol ethers that are either diether or tetraethers. Glycerol diether molecules form a bilayer membrane and glycerol tetraether form a monolayer membrane. Both the ether linkages and the monolayer structure are more rigid than the bilayer ester-linked fatty acids and are more stable at high temperatures and pressures. Archaea tend to inhabit more extreme environments in terms of temperature, pressure, and salt, thus the more stable membrane components allow archaea to survive under these conditions.
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Continuously variable traits typically have a(n) ________, [two words] otherwise known as a "bell-curve."
Fill in the blank(s) with correct word
Which of the following creates pluripotent stem cells without the need to destroy an embryo?
A) embryonic stem cell removal from unused embryos at fertility clinics B) retrieval of stem cells from umbilical cord blood C) retrieval of stem cells from adult bone marrow D) induced pluripotent stem cells
Which meiotic division(s) reduce(s) chromosome number (i.e., meiosis I, meiosis II, or both)? Explain your answer
What will be an ideal response?
Which of the following describes the composition of a nucleotide?
a. a five-carbon sugar, a phosphate group, and one of four amino acids b. a five-carbon sugar, a nitrogenous base, and one of twenty amino acids c. a five-carbon sugar, a phosphate group, and one of four nitrogenous bases d. a six-carbon sugar, a phosphate group, and one of twenty amino acids