Chapter 7 Membrane structure and Function Flashcards Preview

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Flashcards in Chapter 7 Membrane structure and Function Deck (35):
1

Amphipathic

Having both a hydrophilic region and a hydrophobic region

2

Fluid Mosaic Model

cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

3

Integral Proteins

A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein)

4

Peripheral Proteins

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

5

Glycolipids

A lipid with one or more covalently attached carbohydrates

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Glycoproteins

A protein with one or more covalently attached carbohydrates

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Transport Protein

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

8

Aquaporins

A channel protein in a cellular membrane that specifically facilitates osmosis

9

Diffusion

movement of a substance from a region where it is more concentrated to a region where it is less concentrated

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Concentration gradient

A region along which the density of a chemical substance increases or decreases

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Passive Transport

The diffusion of a substance across a biological membrane with no expenditure of energy

12

Osmosis

The diffusion of free water across a selectively permeable membrane

13

Tonicity

The ability of a solution surrounding a cell to cause that cell to gain or lose water

14

Isotonic

a solution that when surrounding a cell, causes no net movement of water into or out of the cell

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Hypertonic

a solution that when surrounding a cell, will cause the cell to lose water

16

Hypotonic

a solution that when surrounding a cell, will cause the cell to take up water

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Turgid

Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential than its surroundings, resulting in entry of water.)

18

Flaccid

Limp. Lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell. (A walled cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water.)

19

Osmoregulation

regulation of solute concentrations and water balance by a cell or organism

20

Plasmolysis

in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment

21

facilitated diffusion

The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure

22

Ion channel

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient

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Gated channel

A transmembrane protein channel that opens or closes in response to a particular stimulus

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Active transport

The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy

25

Sodium-Potassium pump

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

26

Membrane potential

The difference in electrical charge (voltage) across a cell’s plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances

27

Electrochemical gradient

The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion’s tendency to move relative to the membrane potential (an electrical force)

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Electrogenic pump

An active transport protein that generates voltage across a membrane while pumping ions

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Proton pump

An active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process

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Cotransport

The coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient

31

Exocytosis

The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

32

Endocytosis

Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane

33

Phagocytosis

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It
is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells)

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Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes

35

Rector- Mediated endocytosis

The movement of specific molecules into a cell by the infolding of vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances