Question

No matter what the cell type, prokaryotic or eukaryotic, plant or animal, the ____________ forms a protective barrier between the exterior environment and the interior of the cell.
a. cell wall
b. cytoskeleton
c. cell membrane
d. glycoproteins

Answer 1

c. cell membrane forms a protective barrier between the exterior environment and the interior of the cell.

Cell membranes contain membrane proteins that allows all the interaction that occurs within the cell. It makes the cell membrane selectively permeable because of its characteristics as being fluid or its fluidity which means to say that they can move freely within the lipid bilayer. The membrane proteins can also be stored in the lipid bilayer together with the enzymes. It cannot be denied that membrane proteins have a lot of functions based on its type. They can be integral proteins, peripheral proteins and lipid bound proteins.

Answer 2

The most common example of shared characteristics among different types of cells is the cell membrane. Every cell is enclosed by a cell membrane which protects the cell from its surroundings by separating the interior components from the exterior ones.

Further Explanation:

A cell membrane is permeable to selective molecules which means only particular substances can traverse the membrane. The essential molecules are allowed to enter whereas the toxic or non-essential molecules are excreted out of the cell through the cell membrane.

The phospholipids are arranged in a bilayer to form a cell membrane. It also contains the cholesterol present in between phospholipids and maintains the fluidity at different temperatures. The membrane also contains integral and peripheral proteins that help in the transport of materials and maintain the structure and shape of the cell respectively. Glycoproteins are also attached covalently to the membrane and help in cell-cell recognition, cell adhesion, and also serve as receptors for other molecules.

Apart from the cell membrane, certain cells also contain cell walls which surround the cell membrane. It is present in plants, bacteria, and fungi and prevents the over-expansion of the cell. In plants, the cell wall helps in providing turgidity to the cell and also maintains the shape and structure of the cell whereas, humans are devoid of cell walls instead they contain cell membranes.

A cytoskeleton is not a protective barrier for the cell but provides rigidity to the cell and is present in the cytoplasm of the cell. Its main function to provide rigidity to the cell and resistance against deformation by associating with other proteins and connective tissues. It also helps in the transport of material within the cytoplasm and also helps in cell signaling.

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Answer Details:

Grade: High School

Subject: Biology

Chapter: The Cell Membrane

Keywords:

Cell membrane, cytoplasm, cytoskeleton, cell wall, glycoproteins, phospholipid bilayer, cholesterol, glycoproteins, integral proteins, peripheral proteins, cell recognition, cell adhesion, cell signaling.