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Biology 1 > Membranes > Flashcards

Membranes Flashcards

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1
Q

selective permeability

A

an important porperty of biological membranes; some substances can cross more easily than others

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2
Q

amphipathic

A

having both a hydrophilic region and a hydrophobic region; like a phospholipid

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3
Q

fluid mosaic model

A

the membrane is a fluid structure with a “mosaic” of various proteins embedded in or attached to the phospholipid bilayer; parts can fluctuate around laterally

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4
Q

what effect does cholesterol have on membrane fluidity?

A

cholesterol acts as a “fluidity buffer” by reducing fluidity at high temps and reducing rigidity at low temps

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5
Q

normal fluidity of membranes?

A

like salad oil

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6
Q

integral proteins

A

membrane proteins that penetrate into the hydrophobic interior of the lipid bilayer and are bound by hydrophobic interactoins; transmembrane proteins span the membrane

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7
Q

peripheral proteins

A

membrane proteins that are loosely/reversibly bound to the inside surface of the membrane, often exposed to parts of integral proteins

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8
Q

some functions of membrane proteins

A

transport; enzymatic activity; signal transduction; cell-cell recognition; intercellular joining; attachment to the cytoskeleton and extracellular matrix (ECM)

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9
Q

glycolipids

A

carbohydrates covalently bonded to lipids; ex: some membrane carbohydrates are attached to lipids in the plasma membrane; plays a role in cell-cell recognition

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10
Q

glycoproteins

A

carbohydrates covalently bonded to proteins; ex: some membrane carbohydrates are attached to proteins in the plasma membrane; plays a role in cell-cell recognition

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11
Q

where are membrane proteins and lipids synthesized?

A

the ER

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12
Q

where are carbohydrates added to transmembrane proteins? where are they modified?

A

the ER (making glycoproteins); can be modified in the Golgi apparatus

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13
Q

where are carbohydrates added to transmembrane lipids?

A

the Golgi apparaus (making glycolipids)

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14
Q

what transports glycoproteins, glycolipids, and secretory proteins to the plasma membrane?

A

vesicles

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15
Q

what things can/cannot easily pass directly through the lipid bilayer?

A

can pass: small non-polar molecules (hydrocarbons, carbon dioxide, oxygen); can’t pass: large, or polar molecules (ions, sugars, proteins, water)

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16
Q

transport proteins

A

transmembrane proteins that allow specific things to move in or out of the cell; can be passive (uses diffusion) or active (requires energy)

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17
Q

channel proteins

A

a kind of passive transport protein that makes a channel that certain molecules or ions can travel through; facilitated diffusion

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18
Q

aquaporins

A

a kind of channel protein that transports water

19
Q

carrier proteins

A

a kind of passive transport protein that holds onto its passengers and change shape in a way that shuttles them across the membrane; facilitated diffusion

20
Q

diffusion

A

the natural movement of things so that they spread out evenly into the available space, equalizing the concentration

21
Q

concentration gradient

A

a difference in concentrations of a solute, solutes diffuse into areas of lower concentration, down the gradient

22
Q

osmosis

A

the diffusion of water

23
Q

tonicity

A

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

24
Q

isotonic

A

same concentration (a cell in an isotonic solution stays the same)

25
Q

hypertonic

A

higher concentration (a cell in a hypertonic solution shrivels)

26
Q

hypotonic

A

lower concentration (a cell in a hypotonic solution swells)

27
Q

osmoregulation

A

the control of solute concentration and water balance; needed for cells that are exposed to non-isotonic environments, ex: paramecium

28
Q

facilitated diffusion

A

passive transport aided by proteins; ex: channel and carrier proteins

29
Q

ion channels

A

channel proteins that transport ions, many are gated channels

30
Q

gated channels

A

channel proteins which open or close in response to stimulus (electrical, when other things bind to it)

31
Q

active transport

A

transport across the plasma membrane that uses energy to move solutes against their electrochemical gradients

32
Q

passive transport

A

transport across the plasma membrane that uses does not use energy to move solutes; solues move down their electrochemical gradient

33
Q

sodium-potassium pump

A

an active transport system that exchanges 2 Na+ (inside the cell) for 3 K+ (outside the cell) across the plasma membrane of animals

34
Q

membrane potential

A

the voltage across the membrane; about -100mV; favorable for cations in and anions out

35
Q

electrochemical gradient

A

the combination of the chemical (from concentration gradient) and electrical (from potential) forces acting on ions

36
Q

electrogenic pump

A

a transport protein that generates voltage across a membrane, stores energy; ex: sodium-potassium pump in animals, proton pump in plants

37
Q

proton pump

A

actively transports protons, H+, out of the cell

38
Q

cotransport

A

when an electrogenic pump indirectly drives some other active transport

39
Q

exocytosis

A

when a cell secretes stuff via the fusion of vesicles with the plasma membrane

40
Q

endocytosis

A

when a cell takes in stuff by forming new vesicles from the plasma membrane

41
Q

types of endocytosis

A

phagocytosis, pinocytosis, receptor-mediated endocytosis

42
Q

phagocytosis

A

the cell engulfs a particle by extending pseudopodia, creates a food vacuole, lysosome digests it

43
Q

pinocytosis

A

cell gulps drops of extracellular fluid, makes tiny vesicles, non-specific

44
Q

receptor-mediated endocytosis

A

ligands bind to receptors, makes vesicle covered in coat proteins, a way of getting specific things into the cell

Biology 1 (10 decks)

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