Thinking about cell membranes. a) The fatty acid tails of the phospholipids that make up cell membranes can be either saturated or unsaturated. Which type of lipid will lead to a membrane with more mechanical strength? Explain your answer. b) One difference between bacterial and eukaryotic membranes is the presence of cholesterol in eukaryotic membranes. What is the structure of cholesterol? Explain how adding cholesterol to a phospholipid membrane will affect the stability of the membrane. c) “Anammox” bacteria are unique in that they can perform anaerobic ammonia oxidation, or the production of nitrogen gas from ammonia (Damasté et al. Nature 2002, 419, 708.). Intermediates along this reaction pathway include hydrazine (N2H4) and hydroxylamine (NH2OH), both of which are extremely toxic to the cell. The ammonia oxidation reactions are believed to occur inside a membrane- bound structure within the cell called the “anammoxosome.” The structure of one of the lipids of the anammoxosome is shown below and contains a remarkable “ladderane” structure of end-to-end fused cyclobutane rings. i) What effects will this unique lipid structure have on the rigidity, density, and fluidity of the anammoxosome membrane? ii) How do these lipids fit into the paradigm discussed in class that the chemistry of biomolecules reflects the ecological niche in which the organism lives?
Thinking about cell membranes.
a) The fatty acid tails of the phospholipids that make up cell membranes can
be either saturated or unsaturated. Which type of lipid will lead to a membrane
with more mechanical strength? Explain your answer.
b) One difference between bacterial and eukaryotic membranes is the presence
of cholesterol in eukaryotic membranes. What is the structure of cholesterol?
Explain how adding cholesterol to a phospholipid membrane will affect the
stability of the membrane.
c) “Anammox” bacteria are unique in that they can perform anaerobic ammonia
oxidation, or the production of nitrogen gas from ammonia (Damasté et al. Nature
2002, 419, 708.). Intermediates along this reaction pathway include hydrazine
(N2H4) and hydroxylamine (NH2OH), both of which are extremely toxic to the cell.
The ammonia oxidation reactions are believed to occur inside a membrane-
bound structure within the cell called the “anammoxosome.” The structure of one
of the lipids of the anammoxosome is shown below and contains a remarkable
“ladderane” structure of end-to-end fused cyclobutane rings.
i) What effects will this unique lipid structure have on the rigidity,
density, and fluidity of the anammoxosome membrane?
ii) How do these lipids fit into the paradigm discussed in class that the
chemistry of
organism lives?
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