Exam 6: Cell Membranes

Refer to the figures and table below. Human blood cell membranes import iron into the cell via receptor-mediated endocytosis.They do this using transferrin receptors to bind the iron-carrier protein transferrin, which carries two Fe³⁺ ions per protein molecule.Panel A of the figure above shows two transferrin molecules (T_f) bound to one receptor (T_fR).Panel B shows the interaction between the regulatory protein HFE and the transferrin receptor, which results in inhibition of transferrin binding to the transferrin receptor.Genetic mutations in transferrin, transferrin receptor, or HFE can lead to red blood cell dysfunctions.How might mutations be involved in the two cases summarized in the table?

The cell membrane contains carbohydrates, which can serve as recognition sites for other molecules.The carbohydrates may be bonded to

A protein that forms an ion channel in a membrane is most likely to be

In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the molecule's concentration difference across the membrane increases beyond a certain point.The reason is that

Refer to the figure below showing the molecular structure of dimethylmercury. Exposure of human skin to a single drop of dimethylmercury can lead to death, as it passes easily through cell membranes because it is _______.

The membrane protein that transports glucose and sodium ions into intestinal epithelial cells simultaneously is an example of a(n) _______.

Scientists have been able to engineer young laboratory mice to have a defective gene for a particular integrin protein only in epidermal skin cells.These mice develop into adults with severe hair loss and skin blistering.Which statement explains the connection between the mutation and the observed physical problems of the mice?

Which is the name of a specialized cell junction that allows rapid spread of electric current via the flow of ions between animal cells?

Integrin on the cell surface of a white blood cell binds reversibly with the extracellular matrix of blood vessel walls.This reversibility allows for

Refer to the figure below showing concentrations of three ions inside and outside a cell, as well as the direction of transport of each ion facilitated by a membrane protein. Which ions are moved by active transport and why?

Cell adhesion occurs through the interactions of

Which statement correctly describes a trout that lives in fresh water?

Which strategy is paired with an appropriate consequence that would enable a cell to maintain homeostasis when placed in a vessel of pure water?

Refer to the table below. Five compounds labeled A through E are known to be transported into cells across the cell membrane.Some of the properties of each transport mechanism are summarized in the table.A check mark indicates that a compound's transport mechanism has the property described.Which compound might be transported via receptor-mediated endocytosis?

Refer to the figure below. Biologists sometimes use plastic containers called microtiter plates to analyze biological interactions.The microtiter plate contains 96 wells of equal size, each of which holds 0.1-0.3 mL of liquid.When using the plate, a biologist covalently attaches (immobilizes) a different molecule to each well and then add cells suspended in a liquid.After an incubation period, cells that do not bind are washed away, and the whole plate is treated with a cell stain.The amount of stain observed in each well gives an indication of the number of cells binding to the immobilized molecule.Which molecules might the biologist attach to the wells prior to running an experiment to determine the specificity of recognition of a particular cell type for another cell type?

You are examining the membrane of a cell and notice many carbohydrates in the cell membrane.What role do these carbohydrates most likely play?

Vertebrate animals have integral membrane proteins known as cadherins that all have similar structures and function in cell adhesion.Certain mutations in these proteins found in mice cause cells in mouse embryos to fall apart, leading to deaths of the embryos.Some of these mutations could affect the hydrophilic part of the protein molecule, disrupting its ability to recognize and _______to a region of another cadherin molecule.

When cells arrange themselves into groups through cell recognition and specific types of binding, the connections between the cells are further strengthened by _______.

The process by which the cell membrane engulfs large particles or even whole cells is called _______.

Heart defects can cause severe problems in newborn infants.One type of defect occurs when an infant inherits a mutation in the gene encoding connexin, the protein that is the structural component of gap junctions between heart cells.Connexin mutants can cause arrhythmia, which is an abnormal heartbeat.In these cases, cardiac cells are unable to beat in unison because of the lack of a rapid spread of ________ among cells.