CH 7 - Membrane Structure and Function

These flashcards cover key concepts and terminology related to membrane structure and function, facilitating study and comprehension of the topic.

The plasma membrane is the __

boundary that separates the living cell from its surroundings.

The plasma membrane exhibits __ , allowing some substances to cross it more easily than others.

selective permeability

Some small molecules move across the cell membrane using __ transport, which __.

passive; requires no energy input

Large molecules move in and out of cells using __ transport.

bulk

Exocytosis involves the fusion of a __ with the plasma membrane to release contents outside the cell.

vesicle

Phospholipids are __ molecules, containing both hydrophobic and hydrophilic regions.

amphipathic

Phospholipids form a bilayer with hydrophobic __ inside the membrane.

tails

Membranes are held together mainly by weak __ interactions.

hydrophobic

Cholesterol has variable effects on membrane __ depending on temperature.

fluidity

Organisms living in extreme temperatures adapt their __ composition to maintain membrane integrity.

lipid

Peripheral proteins are bound to the __ of the membrane.

surface

The main functions of cell-surface membrane proteins include transport, enzymatic activity, and cell-cell __.

recognition

Osmosis is the __ .

diffusion of free water across a selectively permeable membrane.

A solution is __ if its solute concentration is the same as that inside the cell.

isotonic

In a hypertonic solution, animal cells lose water and may __ , whereas plant cells will __ as the membrane pulls away from the cell wall.

shrivel; plasmolyze

In a hypotonic environment, plant cells become __, which is the healthy state for most plant cells. Animal cells will __.

turgid; lyse/burst

Facilitated diffusion is __ .

passive transport aided by transport proteins

Channel proteins provide corridors that allow specific __ or ions to cross the membrane.

molecules

Active transport requires energy, usually in the form of __ hydrolysis, to move substances against their gradients.

ATP

Membrane potential is created by differences in the distribution of __ across a membrane.

ions

Cotransport occurs when the active transport of a solute __ .

indirectly drives the transport of other substances

In __, transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell.

exocytosis

In __, macromolecules are taken into the cell in vesicles that form from the membrane.

endocytosis

__is defined as cellular eating, where cells engulf particles by extending pseudopodia around them.

Phagocytosis

In receptor-mediated endocytosis, vesicle formation is triggered by binding of solute to __.

receptors

Aquaporins facilitate the __ .

diffusion of water across membranes

Transport proteins include __ proteins and carrier proteins.

channel

The polymerization of __ allows movement of specific substances against their concentration gradient.

ATP

Facilitated diffusion requires no energy because the solute moves __ its concentration gradient.

down

The sodium-potassium pump creates differences in ion __ across the cell membrane.

concentration

The membrane's composition and distribution of proteins, lipids, and carbohydrates is __ across the membrane.

asymmetrical

The plasma membrane is the __\n\n

boundary that separates the living cell from its surroundings.\n\n

The plasma membrane exhibits __ , allowing some substances to cross it more easily than others.\n\n

selective permeability\n\n

Some small molecules move across the cell membrane using __ transport, which __.\n\n

passive; requires no energy input\n\n

Large molecules move in and out of cells using ****__ transport.\n\n

bulk\n\n

Exocytosis involves the fusion of a ****__ with the plasma membrane to release contents outside the cell.\n\n

vesicle\n\n

Phospholipids are ****__ molecules, containing both hydrophobic and hydrophilic regions.\n\n

amphipathic\n\n

Phospholipids form a bilayer with hydrophobic ****__ inside the membrane.\n\n

tails\n\n

Membranes are held together mainly by weak ****__ interactions.\n\n

hydrophobic\n\n

Cholesterol has variable effects on membrane ****__ depending on temperature.\n\n

fluidity\n\n

Organisms living in extreme temperatures adapt their ****__ composition to maintain membrane integrity.\n\n

lipid\n\n

Peripheral proteins are bound to the ****__ of the membrane.\n\n

surface\n\n

The main functions of cell-surface membrane proteins include transport, enzymatic activity, and cell-cell ****__.\n\n

recognition\n\n

Osmosis is the __ .\n\n

diffusion of free water across a selectively permeable membrane.\n\n

A solution is ****__ if its solute concentration is the same as that inside the cell.\n\n

isotonic\n\n

In a hypertonic solution, animal cells lose water and may __ , whereas plant cells will __ as the membrane pulls away from the cell wall.\n\n

shrivel; plasmolyze\n\n

In a hypotonic environment, plant cells become __, which is the healthy state for most plant cells. Animal cells will __.\n\n

turgid; lyse/burst\n\n

What are channel proteins?

Channel proteins are transport proteins that provide corridors allowing specific molecules or ions to cross the membrane.

Active transport requires energy, usually in the form of ****__ hydrolysis, to move substances against their gradients.\n\n

ATP\n\n

Membrane potential is created by differences in the distribution of ****__ across a membrane.\n\n

ions\n\n

An ****__ pump generates voltage across a membrane by storing energy for cellular work.\n\n

electrogenic\n\n

Cotransport occurs when the active transport of a solute indirectly drives the transport of ****__ substances.\n\n

other\n\n

In exocytosis, transport vesicles migrate to the membrane, fuse with it, and release their ****__ outside the cell.\n\n

contents\n\n

In ****__, macromolecules are taken into the cell in vesicles that form from the membrane.\n\n

endocytosis\n\n

Phagocytosis is defined as ****__, where cells engulf particles by extending pseudopodia around them.\n\n

cellular eating\n\n

In an isotonic solution, animal cells are __, while plant cells become __.\n\n

normal; flaccid\n\n

In receptor-mediated endocytosis, vesicle formation is triggered by binding of solute to ****__.\n\n

receptors\n\n

Aquaporins facilitate the diffusion of ****__ across membranes.\n\n

water\n\n

Transport proteins include ****__ proteins and carrier proteins.\n\n

channel\n\n

The polymerization of ****__ allows movement of specific substances against their concentration gradient.\n\n

ATP\n\n

Facilitated diffusion requires no energy because the solute moves ****__ its concentration gradient.\n\n

down\n\n

The sodium-potassium pump creates differences in ion ****__ across the cell membrane.\n\n

concentration\n\n

The membrane's composition and distribution of proteins, lipids, and carbohydrates is ****__ across the membrane.\n\n

asymmetrical\n\n

___ transport moves substances against their concentration gradient, requiring energy. ___ transport moves substances down their concentration gradient, requiring no energy.

Active; Passive\n\n

___ and ___ molecules can pass through the lipid bilayer by simple diffusion.

Small, nonpolar; small uncharged polar (like water, O2, and CO2)\n\n

___ proteins provide a hydrophilic pore for rapid passage, while ___ proteins bind to molecules and undergo a conformational change to transport them.

Channel; carrier\n\n