Proteins in the cell membrane that identify the cell are called A. enzymes
B. transport proteins
C. cell-surface markers
D. receptor proteins

Proteins in the cell membrane that identify the cell are called CELL-SURFACE markers (Option C).

Cell surface markers are specific proteins localized on the cell surface or glycoproteins, which can be used as molecular markers that evidence specific cell types/lineages.

For example, cell surface markers can be used for the identification of the lineage and/or phase of differentiation in lymphocytes such as T cells and B cells.

In lymphocytes, the cell surface markers can be divided into three classes: surface immunoglobulins, differentiation antigens, and membrane receptors.

In conclusion, proteins in the cell membrane that identify the cell are called CELL-SURFACE markers (Option C).

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Proteins in the cell membrane that identify the cell are called cell-surface markers (option C).

Explanation:

Cell surface markers are integral membrane proteins, whose function is to identify specific cell lines, allowing intercellular recognition and communication.

The specific type of cell marker provides the basis for cell classification, allowing studies to be performed on immune system cells, stem cells or atypical cells such as those found in cancer.

The other options are not correct because:

    A. Enzymes are proteins that participate in metabolic reactions.

    B. Transport proteins, although they are also part of membrane proteins, perominate the passage of specific substances through the membrane.

    D. Receptor proteins allow the identification of specific molecules, such as hormones, to couple with them and promote actions inside the cell.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!