The model below shows the structure of a portion of a plasma membrane in an animal cell.

The model shows the structure of a portion of a plasma membrane in an animal cell. None of the parts are labeled, but the model includes a phospholipid bilayer that contains some embedded proteins. The phospholipids are arranged with their heads oriented toward the external and internal membrane surfaces and their fatty acid tails oriented toward the center of the membrane.

Which statement best explains the orientation of the phospholipid molecules in this model?

Question

The model below shows the structure of a portion of a plasma membrane in an animal cell.

The model shows the structure of a portion of a plasma membrane in an animal cell. None of the parts are labeled, but the model includes a phospholipid bilayer that contains some embedded proteins. The phospholipids are arranged with their heads oriented toward the external and internal membrane surfaces and their fatty acid tails oriented toward the center of the membrane.

Which statement best explains the orientation of the phospholipid molecules in this model?

BlackTom AI · Accepted Answer

The model describes a phospholipid bilayer where phospholipids have hydrophilic heads facing the aqueous environments on both sides of the membrane, and hydrophobic tails tucked toward the interior of the bilayer.

Reasoning for the correct option:
- Phospholipids are amphipathic molecules with a polar, hydrophilic head and nonpolar, hydrophobic tails. In an aqueous environment, they arrange themselves so that the heads interact with water, while the tails avoid water by clustering away from it. This drives the formation of a bilayer with the heads pointing outward toward the cytosol and extracellular space and the tails facing inward toward the interior of the membrane.

Why the other potential explanations (which would be incorrect in this context) would fail if considered:
- If one suggested that tails interact with water or that heads point inward, that would contradict the fundamental behavior of phospholipids in water and the observed structure of the bilayer. Tails are hydrophobic and minimize contact with water, so they are sequestered inside.
- Proposals that the orientation is random or that both leaflets expose hydrophobic regions to water would not produce a stable, continuous bilayer in an aqueous environment, and would not align with the image showing a consistent layer of heads at both surfaces.
- Any statement claiming only one side of the membrane interfaces with water, or asserting that the entire bilayer is hydrophobic on both surfaces, would overlook the known placement of polar heads facing the aqueous compartments on either side.

In summary, the arrangement where the hydrophilic phosphate-containing heads face the watery interiors on both sides of the membrane, while the hydrophobic tails point inward away from water, best explains the described phospholipid orientation in this model.

类似问题

Which of the following statements best describes the fluid mosaic model of the plasma membrane:

The lipid bilayer forms the basic structure of the cell membrane.

The plasma membrane (select all that are true):

Question at position 68 Select All That Apply: Which of the following statements is true as it pertains to the head of the cellular membrane?It is hydrophilic.It is water-loving.It is hydrophobic.It is a non-polar molecule.It is water-fearing.It is a polar molecule.

Cholesterol is

One striking feature of plasma membrane structure is its symmetry, with the extracellular and cytoplasmic surfaces virtual mirror images of each other.

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单