micro26,27 - nishi

[ArchivalUser]

Which of the following bacterial transport methods is energy-independent?
A. Facilitated diffusion
B. Simple diffusion
C. Proton gradient energized active transport
D. Group translocation
E. ATP-dependent active transport


Iron is essential in bacterial metabolism. When bacteria invade the human host they must capture iron in order to survive. Which of the macromolecules listed below is important in bacterial iron metabolism?

A. Transferrin
B. Lactoferrin
C. Ferric oxide
D. Lipopolysaccharide (LPS)
E. Siderophores

[ArchivalUser]

b
e?

[ArchivalUser]

EE


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[ArchivalUser]

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[ArchivalUser]

b n e..

[ArchivalUser]

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Almost no important nutrients enter the bacterial cell through simple diffusion, an exception being carbon dioxide and oxygen. Some diffusion, however, is facilitated by specific protein carriers. Most transport, except simple diffusion, is energy-dependent, particularly in Gram-negative bacteria. Group translocation occurs in the absence of oxygen. For example, a simple carbohydrate such as glucose is phosphorylated enzymatically and is then transported into the cell.


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Siderophores such as aerobactin and enterobactin are chelators that trap iron Fe3+. This Fe-chelator complex is actually transported inside the cell. Transferrin and lactoferrin are iron-binding proteins found in blood and milk. Ferric or iron oxide is rust and lipopolysaccharide (LPS) is a microbial cell-wall constituent.