Question

Indicate whether each of the following descriptions better applies to receptor-mediated endocytosis (R), phagocytosis (F), pinocytosis (P), or macropinocytosis (M). Your answer would be a four-letter string composed of letters R, F, P, and M only, e.g. MMPF.

( ) This pathway depends on caveolin and cavin proteins.
( ) Pathogenic particles such as SV40, papillomavirus, and cholera toxin enter the cell via this pathway.
( ) In animals, this pathway is normally limited to professional cells such as neutrophils.
( ) This pathway proceeds by the formation of highly ruffled regions in the plasma membrane which then collapse, resulting in fluid uptake.

Answer 1

PRFM

Step-by-step explanation:

• Receptor-mediated endocytosis is a process where cells absorb proteins, hormones, metabolites and sometimes viruses with the formation of an invagination (inward budding of the plasma membrane). Cholera toxin, flu viruses, and diphtheria have sites that cross-react with receptor-binding sites and gain entry into cells through this pathway. Pathogenic particles such as SV40, papillomavirus, and cholera toxin enter the cell via this pathway.

• Phagocytosis is when a cell ingests or engulf large cells (up to 0.5 µm) or small particles to remove them from circulation. Neutrophils and Macrophages are an example of cells that phagocyte. In animals, this pathway is normally limited to professional cells such as neutrophils.

• Pinocytosis, also known as fluid endocytosis is the process by which liquid droplets are ingested by a cell. Potocytosis is a variation of pinocytosis, the vehicle for internalization is the caveola, an invagination formed by proteins called caveolin. This pathway depends on caveolin and cavin proteins.

• Macropinocytosis is the engulfment and uptake process of large amounts of fluids by the appearance of numerous irregular ruffles that eventually collapse towards the cell membrane, enveloping the content. This pathway proceeds by the formation of highly ruffled regions in the plasma membrane which then collapse, resulting in fluid uptake.

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