Question

A student proposes six models of a hypothetical plasma membrane (figure 1). Identify the model that best represents the plasma membrane of a hypothetical cell that exists in a non-aqueous environment and whose cytosol is similar to that of an animal cell. Provide TWO pieces of reasoning to support your identification

Answer 1

Answer:

The model that best describes the plasma membrane of the hypothetical cell is E

Explanation:

The model that best represents the plasma membrane of a hypothetical cell that exists in a non-aqueous environment and whose cytosol is similar to that of an animal cell is E

The reasons behind the answer are

1) The cytosol of an animal cell is an aqueous solution that surrounds the internal organelles attached to the cytoplasm. Since the model describes the cytosol to be similar to that of an animal cell, then the cytosol will be aqueous cytosol.

2) The plasma membrane of a cell in an aqueous environment is made up of phospholipid bilayer (where the head/phosphate group is hydrophilic and the tail/lipid is hydrophobic) in which the head of each lipid layer is oriented inwards while the tails are oriented outward. This allows for molecules that are hydrophobic to easily pass through the membrane since they are like the inward hydrophobic tails while hydrophilic molecules cannot pass easily except by activated carriers. However, if the cell is in a non-aqueous environment, there might not be a bilayer as the lipid/hydrophobic tail does not interact with water or another hydrophilic head because of the absence of bond to hold it together. This thus causes the head to interact with the aqueous solution inside the cell and the tail interact with the non aqueous environment outside the cell while each part of the phospholipid regulating what goes in/out of the cell individually.

Answer 2

Phospholipids have hydrophobic tails -that can not touch the water-, and hydrophilic heads -that must be in contact with an aqueous environment-. Model E best represents the plasma membrane of the hypothetical cell.

-----------------------------------------

Lipids are individual medium-sized molecules.

There are different types of lipids: triacylglycerols, wax esters, phosphoglycerides, sphingolipids, and sterols.

According to their structure:

• Simple lipids ⇒ Composed of an alcohol molecule and fatty acids.

• Complex lipids ⇒ They are composed of alcohol, fatty acids, and different non-lipidic components, such as phosphates, amino acids, glucyds, amines, etcetera. These are the amphipathic molecules.

The proposed models of the membrane are composed of phospholipids.

• The lipidic head corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion.

• The lipidic tails correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.

Since membrane lipids are amphipathic molecules, they need to establish specific structures.

These structures vary according to the environment they are in contact with.

• Their hydrophilic polar heads can be in contact with water.

• Their hydrophobic tails can not be in contact with an aqueous environment.

According to this hypothetical cell,

• Hydrophobic tails can not be facing the cytosol, but hydrophilic heads can.

The cytosol is similar to that of the animal cell, which means it is aqueous. Since tails can not be in contact with water, only phospholipid heads can be facing the interior of the cell.

• Hydrophobic tails must be facing the exterior of the cell.

The extracellular space is non-aqueous, which means that the phospholipids' tails can be in contact with this environment. But hydrophilic heads can not.

Only one layer of lipids is enough to form the membrane.

The membrane model expressing all these characteristics is model E.

• Aqueous cytosol

• Non-aqueous extracellular space

• Hydrophobic tails facing the exterior

• Hydrophilic heads facing the interior

-------------------------------------------------------------------

Related link: https://brainly.com/question/9824228?referrer=searchResults

                     https://brainly.com/question/3037318?referrer=searchResults