Question 1

Tissues are made up of specialized groups of cells with similar functions.Animal cells are able to arrange themselves through

Accepted Answer

Animal cells are able to arrange themselves through cell recognition and cell adhesion. This allows cells with similar functions to come together and form tissues. Desmosomes, tight junctions, gap junctions, and vesicle transport may play a role in maintaining tissue structure and function, but they are not the primary mechanisms for cell arrangement.

Question 2

Refer to the table below.  Which statement about biological membranes is supported by these data?

Accepted Answer

The answer of Refer to the table below.  Which...

Question 3

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?

Accepted Answer

Oligosaccharides are carbohydrates consisting of a small number of monosaccharides (simple sugars) linked together. They are commonly involved in cell-cell recognition and adhesion. Therefore, attaching different oligosaccharides to each well can help determine the specificity of recognition of a particular cell type for another cell type.

Question 4

Male and female reproductive cells in animals can recognize each other via specific glycoproteins present on their cell surfaces.Each cell produces a different glycoprotein that recognizes the other.This is an example of _______ binding.

Accepted Answer

Heterotypic binding refers to the interaction between two different types of cells or molecules, in this case, male and female reproductive cells recognizing each other through specific glycoproteins.

Question 5

A biologist is interested in identifying pairs of molecular structures responsible for adhesion between bovine (cow) intestinal cells.Which pairs of structures should the biologist include as possibilities during his search?

Accepted Answer

Cell adhesion often involves interactions between proteins (such as cadherins and integrins) and carbohydrates (such as those found in the extracellular matrix), as well as protein-protein interactions. These interactions are crucial for the structure and function of tissues.

Question 6

The hydrophilic regions of a membrane protein are most likely to be found

Accepted Answer

Hydrophilic regions of membrane proteins are typically charged or polar and therefore interact with water molecules. They are therefore most likely found on the exterior surface of the membrane, where they can interact with the aqueous environment outside the cell or organelle.

Question 7

A student claims that both freeze-fracturing techniques and cell fusion experiments provided evidence that supported the fluid mosaic model used to describe the cell membrane.Which statement best evaluates this student's claim?

Accepted Answer

Both freeze-fracturing techniques and cell fusion experiments supported the fluid mosaic model in different ways. Freeze-fracturing techniques revealed the presence and distribution of proteins within the lipid bilayer, while cell fusion experiments showed how proteins could move within a membrane. Therefore, the statement in option B accurately reflects how both techniques contributed to the evidence for the fluid mosaic model.

Question 8

A cell membrane contains many types of proteins.Which type of protein would most easily be removed from the cell membrane in aqueous conditions in a laboratory experiment?

Accepted Answer

Peripheral proteins are loosely attached to the cell membrane and are easily removed in aqueous conditions. In contrast, integral proteins, including channel proteins and transmembrane proteins, are embedded within the membrane and require harsher conditions, such as detergents, to be removed. Gated channels are a type of integral protein and also require more specific techniques to remove from the membrane.

Question 9

A biologist wants to compare the integral membrane protein content of cells from mouse liver, pancreas, and intestine.Which experimental procedure should she choose?

Accepted Answer

Freeze-fracture electron microscopy is a technique that allows for the observation of the arrangement and distribution of integral membrane proteins within the lipid bilayer of cell membranes, making it suitable for comparing the integral membrane protein content of cells from different tissues.

Question 10

A researcher studying a line of mouse skin cells has identified an oligosaccharide group attached to the cells' surfaces.What experiment should the researcher perform to test whether this oligosaccharide is important in cell-cell recognition?

Accepted Answer

Enzymatic hydrolysis of the oligosaccharide would allow for testing whether it is involved in cell recognition because this treatment would remove the oligosaccharide from the cell surface. If it is important in cell-cell recognition, the treated cells would no longer recognize other cells. Other choices may also provide useful information, but only E directly tests the hypothesis that the oligosaccharide is important in cell recognition.

Question 11

A transmembrane protein may contain one or more hydrophilic side chains.If these were removed, the rest of the protein molecule would

Accepted Answer

Hydrophilic side chains prefer to be in contact with the aqueous environment, so their removal would leave the rest of the protein with hydrophobic side chains that would remain embedded within the hydrophobic interior of the membrane. Therefore, the protein would still be within the membrane after removal of the hydrophilic side chains.

Question 12

Freeze-fracturing is a useful tool for revealing _______ proteins.

Accepted Answer

Freeze-fracturing is a technique used to study the internal structure of cell membranes. Since it involves rapidly freezing and fracturing the membrane, it is particularly useful for studying transmembrane proteins - those that span the lipid bilayer of the membrane. Therefore, the best choice is E) transmembrane proteins. Peripheral, cytosolic, asymmetric, and cytoskeletal proteins are not specifically studied using freeze-fracturing.

Question 13

Which molecule can function as a recognition signal for interactions between animal cells?

Accepted Answer

Glycoproteins are proteins that have carbohydrates attached to them, and they often serve as recognition signals for interactions between animal cells. These carbohydrates can be involved in cell signaling and can play a role in cell adhesion, immune responses, and development. RNA, phospholipids, cholesterol, and fatty acids are all important molecules in the cell, but they do not typically serve as recognition signals for cell-cell interactions.

Question 14

Specialized cells in the heart are able to maintain a rhythmic heartbeat due to the rapid spread of electrical current through

Accepted Answer

Gap junctions are specialized protein channels that connect adjacent cells and allow for the rapid spread of electrical impulses. In the heart, these gap junctions allow for coordinated contractions and maintain a rhythmic heartbeat. Tight junctions and desmosomes are involved in cell adhesion and do not play a role in electrical signaling. Neurons are not specialized cells in the heart. Channel proteins also allow for the movement of ions, but they do not allow for rapid electrical signaling between cells.

Question 15

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

Accepted Answer

Ion channels require a protein to span the membrane, which means the protein must be a transmembrane protein in order to form a channel for ions to pass through. Peripheral proteins are found on the surface of the membrane and do not span the entire membrane. Phosphorylation refers to the addition of a phosphate group to a protein, which does not necessarily determine its location or function in the membrane. Enzymes also do not necessarily span the entire membrane and are not specifically designed to form a channel for ions. Proteins entirely outside the phospholipid bilayer would not have access to ions passing through the membrane.

Question 16

Refer to the table below.  The data in the table were collected during an analysis of neuronal cell membranes from fish of a single species transferred from a cold environment to a warm one.Which statement is consistent with these data and with what you know about membrane fluidity?

Accepted Answer

The answer of Refer to the table below.  The...

Question 17

Which analogy could best be used to describe the molecular structures interacting at the point of attachment between two animal cells physically bound to one another?

Accepted Answer

The interaction between molecular structures at the point of attachment between two animal cells can be described as a key inserted into a lock where the two structures fit together perfectly and are tightly bound.

Question 18

Refer to the figure and table below. At low temperatures, cell membranes become quite immobile and solid-like.If the temperature is gradually increased, a membrane undergoes small changes until a large change in fluidity is observed.The midpoint temperature corresponding to this large change is called the melting temperature.The graph shows how a cell membrane's melting temperature (T_m) is measured.The table shows melting temperature data collected from membranes composed of phospholipids containing different fatty acids.Which statement is consistent with these data?

Accepted Answer

The table shows that as the chain length decreases or double bonds are introduced, the melting temperature decreases, indicating an increase in membrane fluidity. Therefore, decreasing chain length or introducing double bonds into fatty acids in membrane phospholipids increases temperature-dependent membrane fluidity. Option A, B, D, and E are incorrect as they make opposite or contradictory statements.

Question 19

Cell adhesion in animals often occurs through the interactions of

Accepted Answer

The answer of Cell adhesion in animals often occurs through...

Question 20

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

Accepted Answer

Carbohydrates in the cell membrane are usually attached to lipids and proteins, forming glycolipids and glycoproteins, respectively. These serve as recognition sites for other molecules, including signaling molecules and immune cells.

Quiz 6: Cell Membranes