Bio 110 Chapter 7 Quiz Terms are Questions
Which of the following is true of the evolution of cell membranes?
All components of membranes evolve in response to natural selection.
Who was/were the first to propose that cell membranes are phospholipid bilayers?
E. Gorter and F. Grendel
Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?
Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
In the years since the proposal of the fluid mosaic model of the cell membrane, which of the following observations has been added to the model?
The concentration of protein molecules is now known to be much higher.
Why are lipids and proteins free to move laterally in membranes?
There are only weak hydrophobic interactions in the interior of the membrane.
According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
They can move laterally along the plane of the membrane.
A protein that spans the phospholipid bilayer one or more times is
a transmembrane protein.
In order for a protein to be an integral membrane protein it would have to be
amphipathic, with at least one hydrophobic region.
The movement of potassium into an animal cell requires
an energy source such as ATP.
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. As a result, these lipid rafts
are more rigid than the surrounding membrane.
Which of the following 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
The presence of cholesterol in the plasma membranes of some animals
enables the membrane to stay fluid more easily when cell temperature drops.
A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in
lysosomes.
Singer and Nicolson's fluid mosaic model of the membrane proposed that
membranes consist of protein molecules embedded in a fluid bilayer of phospholipids.
Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?
peripheral proteins
Which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
The difference between pinocytosis and receptor-mediated endocytosis is that
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that
the hydrophobic interactions that hold the membrane together are weakest at this point.
The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is
to mediate cell-to-cell recognition
