Chapter 6 Flashcards
Which of the following processes does not involve the uptake of materials into the cell?
A. Exocytosis
B. Pinocytosis
C. Endocytosis
D. Receptor-mediated endocytosis
E. Phagocytosis
A
Active transport usually moves molecules
A. in the same direction as diffusion moves them.
B. in a direction opposite to the one in which diffusion moves them.
C. in a direction that tends to bring about equilibrium.
D. toward a higher pH.
E. toward higher osmotic potential.
B
The difference between osmosis and diffusion is that
A. diffusion is passive transport, whereas osmosis is active transport.
B. only in diffusion do molecules move from areas of high concentrations to areas of low concentration.
C. only diffusion refers to the movement of materials across a semipermeable membrane.
D. diffusion is the movement of molecules, wereas osmosis refers specifically to the movement of water.
E. the process of osmosis varies according to the kinds of particles present.
D
Which of the following is not a function of plasma membranes?
A. Conversion of glucose energy to ATP
B. Arrangement of enzymes
C. Turning off of a specific cell function
D. Conduction of nerve impulses
E. All of the above are functions of plasma membranes.
E
Water crosses the plasma membrane at a rate faster than expected for simple diffusion because of
A. the hydration of the ions as they pass through.
B. water channels called aquaporins.
C. gated channels.
D. Both a and b
E. All of the above
D
Which of the following functions as a recognition signal for interactions between cells?
A. RNA
B. Phospholipids
C. Cholesterol
D. Fatty acids
E. Glycolipids
E
Which of the following molecules is the most likely to diffuse across a cell membrane?
A. Glucose
B. Na+
C. A steroid
D. A common amino acid
E. Cl-
C
One result of the movement of ions through ion channels is the creation of a membrane potential. The membrane potential is
A. a charge imbalance across the plasma membrane.
B. the difference in ion concentrations on either side of the plasma membrane.
C. the difference in ATP concentrations on either side of the plasma membrane.
D. the capacity for active transport.
E. the ability of macromolecules to recognize and adhere to one another.
A
Osmosis moves water from a region of ___ to a region of ___.
A. high concentration of dissolved material; low concentration of dissolved material
B.low concentration of dissolved material; high concentration of dissolved material
C. hypertonic solution; hypotonic solution
D. negative osmostic potential; positive osmotic potential
E. low concentration of water; high concentration of water
B
Receptor-mediate endocytosis is the mechanism for transport of
A. clathrin.
B. all macromolecules.
C. ions.
D. cholesterol.
E. integral membrane proteins.
D
Protein movement within a membrane may be restricted by
A. glycolipids and glycoproteins.
B. closure fo gated channels.
C. the cytoskeleton.
D. cell adhesion.
E. tight junctions and desmosomes.
C
Which of the following statements about diffusion is false?
A. Diffusion depends ont eh intrinsic kinetic enrgy of molecules.
B. Diffusion continues until the concentrations are in equilibrium.
C. In diffusion, molecules move from areas fo greater concentration to areas of lesser concentration.
D. Diffusion is a random proces..
E. Simple diffusion depends upon specific carrier proteins.
C
Biological membranes are composed of
A. nucleotides and nucleosides.
B. enzymes, electron acceptors, and electron donors.
C. fatty acids.
D. monosaccharides.
E. lipids, proteins, and carbohydrates.
E
Which of the following is not involved in secondary active transport?
A. The direct use of ATP
B. Coupling to another transport system
C. Use of an existing concentration gradient
D. The plasma membrane
E. The ability to concentrate the transported molecule.
A
This figure depicts the molecular structure of a typical phospholipid bilayer. Which of the following statements regarding phospholipid bilayers is false?
A. Phospholipids have both hydrophobic and hydrophilic regions.
B. In water, phospholipids tend to aggregate to form a bilayer.
C. Individual phospholipids are free to change sides of the bilayer.
D. The hydrophobic interior of the membrane is an oil-like fluid.
E. The inner and outer halves of a bilayer often differ in phospholipid composition.
C
Membrane Components: In the accompanying figure of an integral membrane protein, which one of the following groups of terms correctly describes the three labeled regions (1, 2, 3) of the protein?
A. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophilic
B. 1 = hydrophobic; 2 = hydrophobic; 3 = hydrophilic
C. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophobic
D. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophobic
E. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophilic
A
Which of the following statements regarding homotypic cell binding (shown) is false?
A. Identical proteins are found on the surfaces of cells that bind together to form tissues.
B. Tissue formation generally depends on homotypic cell binding.
C. The molecules involved in homotypic cell binding in sponges are glycoproteins.
D. Homotypic cell binding requires that only one cell in a binding pair contain the binding protein.
E. Separated cells from two different species of sponge will re-aggregate only with cells of the same type due to homotypic cell binding.
D
Which of the following is not a function of animal tight junctions (shown)?
A. Forcing substances to pass through epithelial cell membranes rather than intercellular spaces
B. Restricting movement of materials within intercellular spaces
C. Allowing communication between adjacent epithelial cells
D. Restricting movement of proteins and phospholipids within the cell membrane
E. Dividing the cell into an apical and basolateral region
C
Which of the following is not a function of animal gap junctions (shown)?
A. Facilitating communication between cells
B. Providing mechanical stability
C. Allowing passage of dissolved molecules between cells
D. Providing mechanism for transmission of electric signals between cells
E. Connecting the interior of adjacent cells through the presence of connexons
B
Which one of the following would not affect the rate of diffusion of the three solutes shown in the accompanying figure?
A. Osmosis
B. Size of the solute particles
C. Temperature
D. Electrical charge of the solute
E. Concentration gradient
A
Which of the following statements regarding the sequence of events shown here is true?
A. The cells in condition C have been immersed in a hypertonic solution.
B. The concentration of solutes inside the cell shown in condition C is higher than the solution surrounding the cell.
C. The cells in condition A have been immersed in a hypotonic solution.
D. Osmosis occurs when going from condition B to C, but not from B to A.
E. Diffusion of solutes out of the cell is causing the events shown in the transition from conditions B to A.
B
Which of the following statements regarding the sequence of events shown here is true?
A. The cell in condition B has less turgor pressure than the cell in condition A.
B. The cells in condition A have been placed in a hypotonic solution.
C. The cells in condition C have been placed in a hypertonic solution.
D. The cells in condition C have been placed in an isotonic solution.
E. The cell in condition C has a greater turgor pressure than the cell in condition B.
E
Which of the following statements regarding channel proteins is false?
A. Channel proteins can assist polar molecules to cross the plasma membrane in a process called facilitated diffusion.
B. The gated ion channel can allow ions to pass when stimulated to open.
C. Ion channels restrict movement of ions based upon size and charge.
D. Water plays a role in determining which ions are allowed to pass through an ion channel.
E. The channel of most channel proteins contains polar amino acids and water.
C
Which combination of terms best describes the transport mechanism shown in the following figure?
A. Simple diffusion; uniport
B. Simple diffusion; antiport
C. Active transport; uniport
D. Active transport; symport
E. Active transport; antiport
E
Which of the following statements regarding the transport system(s) shown here is false?
A. Both primary and secondary active transport processes are depicted in the diagram.
B. Both primary and secondary active transport processes move ions against their concentration gradients.
C. Both primary and secondary active transport processes require energy.
D. Secondary active transporters can move large molecules across the membrane.
E. Both primary and secondary active transport processes require the activity of a membrane protein.
B
The process shown in the following figure is called
A. diffusion.
B. osmosis.
C. facilitated diffusion.
D. endocytosis.
E. exocytosis.
D
The process of receptor-mediated endocytosis is shown in the accompanying figure. Which of the following statements regarding this process is false?
A. Receptor-mediated endocytosis requires receptor proteins located on the cell’s surface.
B. Coated pits are lined on their cytoplasmic surface by clathrin.
C. Receptor-mediated endocytosis is important in cellular uptake of cholesterol.
D. Coated vesicles eventually become part of the endoplasmic reticulum.
E. Coated vesicles contain previously extracellular material.
D
Which of the following statements about the receptor system shown here is false?
A. This system is an example of information processing in the cell.
B. One type of signal molecule that acts via this mechanism is insulin.
C. Binding of the signal to the receptor protein causes some response in the cell.
D. Receptors of this type can initiate, modify or halt particular cell functions.
E. When bound, the receptor protein transports the signal molecule into the cell.
E
Which statement about membrane phospholipids is not true?
A. They associate to form bilayers.
B. They have hydrophobic “tails.”
C. They have hydrophilic “heads.”
D. They give the membrane fluidity.
E. They flip-flop readily from one side of the membrane to the other.
E
Which statement about membrane proteins is not true?
A. They all extend from one side of the membrane to the other.
B. Some serve as channels for ions to cross the membrane.
C. Many are free to migrate laterally within the membrane.
D. Their position in the membrane is determined by their tertiary structure.
E. Some play roles in photosynthesis.
A
Which statement about membrane carbohydrates is not true?
A. Some are bound to proteins.
B. Some are bound to lipids.
C. They are added to proteins in the Golgi apparatus.
D. They show little diversity.
E. They are important in recognition reactions at the cell surface.
D
Which statement about animal cell junctions is not true?
A. Tight junctions are barriers to the passage of molecules between cells.
B. Desmosomes allow cells to adhere firmly to one another.
C. Gap junctions block communication between adjacent cells.
D. Connexons are made of protein.
E. The fibers associated with desmosomes are made of protein.
C
Which statement about osmosis is not true?
A. It obeys the laws of diffusion.
B. In animal tissues, water moves into cells if they are hypertonic to their environment.
C. Red blood cells must be kept in a plasma that is hypotonic to the cells.
D. Two cells with identical solute concentrations are isotonic to each other.
E. Solute concentration is the principal factor in osmosis.
C
Which statement about ion channels is not true?
A. They form pores in the membrane.
B. They are proteins.
C. All ions pass through the same type of channel.
D. Movement through them is from regions of high concentration to regions of low concentration.
E. Movement through them is by simple diffusion.
C
Facilitated diffusion and active transport both
A. require ATP.
B. require the use of proteins as carriers or channels.
C. carry solutes in only one direction.
D. increase without limit as the concentration gradient increases.
E. depend on the solubility of the solute in lipids.
B
Primary and secondary active transport both
A. generate ATP.
B. are based on passive movement of Na+ ions.
C. include the passive movement of glucose molecules.
D. use ATP directly.
E. can move solutes against their concentration gradients.
E
When a hormone molecule binds to a specific protein on the plasma membrane, the protein it binds to is called a
A. ligand.
B. clathrin.
C. receptor protein.
D. hydrophobic protein.
E. cell adhesion molecule.
C
You are studying how the protein transferrin enters cells. When you examine cells that have taken up transferrin, you find it inside clathrin-coated vesicles. Therefore, the most likely mechanism for uptake of transferrin is
A. facilitated diffusion.
B. an antiporter.
C. receptor-mediated endocytosis.
D. gap junctions.
E. ion channels.
C
pinocytosis
endocytosis of liquid containing dissolved substances
hypotonic
having smaller comparative solute concentration
glycoprotein
protein with attached carbohydrates/sugars
endocytosis
process in which liquids or solid particles are taken up by a cell through invagination of plasma membrane
aquaporin
transport protein in plasma membrane through which water passes during osmosis
phagocytosis
endocytosis of another cell or large particle
cell junctions
structures associated with plasma membranes:
plasmodesmata (plant cells)
desmosome (animal cells)
gap junctions
tight junctions
ligand
molecule that binds to receptor site of another molecule
(usually smaller than receptor)
hypertonic
having greater comparative solute concentration
gated channel
membrane protein that changes 3D shape in response to a stiumlus to all passage of specific ions across plasma membrane
cell adhesion molecules
molecules on animal cells that affect selective association of cells into tissues during embryotic development
antiporter
(def and example)
membrane transport protein that moves a substance in one direction and another substance in the opposite direction
(Na+/K+ pump)
primary active transport
active transport in which ATP is directly hydrolyzed
carrier protein
membrane protein that binds a specific molecule and transports it through plasma membrane
FACILITATED DIFFUSION
channel protein
integral membrane protein that forms aqueous passage across membrane through which specific solutes may pass
diffusion
random movement of atoms or molecules; tends toward equilibrium/even distribution
uniporter
membrane transport protein that carries single substance in one direction
glycolipid
lipid to which carbohydrate(s)/sugar(s) are attached
transmembrane protein
integral membrane protein that spans the entire phospholipid bilayer
secondary active transport
form of active transport that doesn’t directly utilize ATP
active transport coupled to ion diffusion down a concentration gradient established in primary active transport
integral membrane protein
protein embedded in phosopholipid bilayer of membrane
isotonic
having the same comparative solute concentration
receptor-mediated endocytosis
endocytosis initiated by macromolecular binding to a membrane receptor
membrane potential
different in electric charge between inside of cell and outside of cell
due to difference in distribution of ions
freeze-fracturing
(definition)
method of tissue preparation for transmission and scanning electron microscopy
freeze-fracturing
(process)
tissue is frozen and knife is used to crack open tissue
fracture often occurs along path of least resistance; within a membrane
peripheral membrane protein
membrane protein not embedded in the phospholipid bilayer
symporter
memtrane transport protein that carries two substances in the same direction
receptor protein
protein with ability to bind to specific molecule or to detect specific stimulus
can be wihin cellular environment or external to cell
integrin
transmembrane protein that mediates attachment of epithelial cells to extracellular matrix
ion channel
integral membrane protein that allows ions to diffuse across membrane
sodium-potassium pump
antiporter responsible for primary active transport; both ions are pumped against concentration gradients
pumps 3 Na+ ions out of cell
pumps 2 K+ ions into cell
tight junction
junction between epithelial cells in which no gap is present between adjacent cells
limits passage of molecules through extracellular fluid between cells
active transport
process requiring energy to transport a substance across a biological membrane against the concentration gradient
facilitated diffusion
passive movement through membrane down a concentration gradient; utilizes a specific carrier protein
selective permeability
permeable to some substances but not to others
characteristic of membranes
homotypic
adhesion of cells of the same type
fluid mosaic model
molecular model for structure of membranes consisting of fluid phospholipid bilayer in which suspended proteins are free to move in bilayer plane
osmosis
movement of water across a membrane
from positive potential to negative potential (or more negative potential)
heterotypic
adhesion of cells to different cell types
gap junction
junction between plasma membrane (spanned by protein channels) of two animal cells allowing passage of chemical substances or electrical signals
desmosome
adhering junction between animal cells
cell recognition
binding of cells to one another mediated by membrane proteins/carbohydrates
passive transport
diffusion across a membrane; carrier or channel protein may be used, but not necessarily
turgor pressure
hydrostatic pressure of an enclosed solution (greater than atm pressure)
exocytosis
process by which vesicle fuses to plasma membrane to release contents to the outside of the cell
