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Biochemistry - Cell Biology and Lipids - MCAT Practice Questions

The structure of the plasma membrane, accounting for the dynamic nature of lipids, proteins, and carbohydrates, is described by which model?
Fluid Mosaic Model






Lipids move freely in the plane of the cell membrane and can assemble into specialized regions known as:
Lipid rafts






The specific membrane protein responsible for maintaining the bidirectional transport of lipids between the two layers of the phospholipid bilayer is a/an:
Flippase






Triacylglycerols and fatty acids serve as direct precursors to which major class of membrane lipids?
Phospholipids






Glycerophospholipids are similar to triacylglycerols, except one of the fatty acids is replaced with a/an:
Phosphate group






Which component contributes to both the fluidity and stability of the cell membrane?
Cholesterol






At low temperatures, cholesterol acts to increase membrane fluidity primarily by:
Preventing fatty acid hydrocarbon chains from crystallizing






At high temperatures, cholesterol acts to decrease membrane fluidity primarily by:
Immobilizing a few methylene groups in the fatty acid tails






Which type of lipid, often prevalent in plants, provides waterproofing and defense for the cell?
Waxes






A type of integral protein that spans the entire cell membrane is a/an:
Transmembrane protein






Proteins and carbohydrates may move within the membrane, but their movement is slowed by their:
Relatively large size






Proteins that have one or more segments embedded in the phospholipid bilayer are classified as:
Integral proteins






Carbohydrates on the cell membrane can form a protective surface layer known as a/an:
Glycoprotein coat






When extracellular ligands bind to membrane receptors, the immediate effect is to:
Initiate a response within the cell






Which type of cell junction prevents solutes from leaking into the space between cells via a paracellular route?
Tight junctions






Which cell junction allows for the rapid exchange of ions and other small molecules between adjacent cells?
Gap junctions






Cell junctions that bind adjacent cells by anchoring to their cytoskeletons are called:
Desmosomes






The pressure that must be applied to a solution to prevent the inward flow of water (to prevent osmosis) is defined as:
Osmotic pressure






In the context of carbohydrates, an α-glycosidic bond involves the C1 anomeric carbon pointing:
Down (trans to C6 in the chair conformation)






Embedded proteins are most likely involved in which of the following cellular processes?
Cellular communication or part of a catalytic complex