According to the fluid mosaic model of cell membranes, what is a true statement about membrane phospholipids?
They can move laterally along the plane of the membrane
What is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
by increasing the percentage of unsaturated phospholipids in the membrane
What types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
Celery stalks that are immersed in fresh water for several hours remain the same firmness as they were before being immersed. Simliar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are
isotonic to fresh water but hypotonic to the salt solution
When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid
Cells bring in very small particles into the cell as these particles collect along the cell membrane through what process?
In order for a protein to be an integral membrane protein it would have to be which of the following?
What is not embedded in the lipid bilayer at all?
What serve as receptors or cell recognition molecules on cell surfaces?
What would be true according to the theory of evolution of cell membranes?
as populations of organisms evolve, different properties of their cell membrnaes are selected for or against
What kinds of molecules pass through a cell membrane unaided (no channels) most easily?
small and hydrophobic
What is a correct statement about diffusion?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
The proton pump found in most plant cells and many animal cells is most accurately described as
it requires an expenditure of energy by the cell
Which membranes activity requires energy from ATP hydrolysis?
Na+K+Pumping of ions across a cell membrane
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, what transport mechanism is most probably functioning in the intestinal cells?
Water passes quickly through cell membranes because...
it moves through aquaporins in the membrane
In receptor-mediated endocytosis, receptor molecules use what "joining" structure in order to successfully bind to the molecule it is helping to actively cross the membrane?
the large molecules of all living things fall into what 4 classes?
1. carbohydrates 2. lipids 3. proteins 4. nucleic acids
allows some substances to cross more easily than others
has both a hydrophilic and hydrophobic region
the movement of molecules of any substance so that they spread out evenly into the available space