Question

In: Biology

1. Which of the following would increase the rate at which integral membrane proteins move from...

1. Which of the following would increase the rate at which integral membrane proteins move from one end of the cell to the other?

	A.	An increase in temperature
	B.	An increase in pH
	C.	A decrease in the number of double bonds in the fatty acid tails of the membrane phospholipids
	D.	An increase in the length of the fatty acid tails of the membrane phospholipids

2. Some bacteria produce toxins that allow them to pass across the epithelial layer in the lining of the gut. Which type of cell-to-cell junction do these toxins affect?

	A.	Tight junctions
	B.	Plasmodesmata
	C.	Adhesive junctions (e.g. desomosomes)
	D.	Gap junctions

Expert Solution

1.

Answer: A. An increase in temperature

Explanation:

When temperature is increased, the kinetic energy and hence fluidity of the membrane increases. As a result, the integral protein can easily swim in the lipid bilayer of the membrane and reach the other end of the cell.

An increase in pH has no significant effect on cell membrane fluidity

A decrease in the number of double bonds in the fatty acid tails of the membrane phospholipids makes the membrane more rigid and hence the integral protein would take more time to reach the other end of the cell

An increase in the length of the fatty acid tails of the membrane phospholipids would again increase the rigidity of the cell membrane by maximizing the hydrophobic interactions

2.

Answer: A. Tight junctions

Explanation:

The wall of gut/intestine has a special system of barrier that, on one hand, allows the absorption of useful nutrients and on the other hand, blocks substances that should not gain access to the body. Epithelial cells that make up the wall of the intestine provide support to the barrier system. The spaces between the epithelial cells are sealed tightly by the tight junctions which consist of proteins. When a gram negative bacteria enters the body, its lipopolysaccharide endotoxin(LPS) causes the permeability of tight junctions to increase. This causes 'leaky gut'.

Plasmodesmata are a part of plants and connect adjacent plant cells

Adhesive junctions are more basal in their positioning than the tight junctions and are hence not involved

Gap junctions are cell to cell connections in adjacent animal cells and thus are like the plasmodesmata.

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gladiator answered 2 years ago

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