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BIOL 2010 > Cellular Interactions and Cell Membrane Transport > Flashcards

Cellular Interactions and Cell Membrane Transport Flashcards

1
Q

define the extracellular matrix (ECM)

A

cells that make up tissues/organs are embedded in extracellular material

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2
Q

what is the ECM made of

A

protein fibres, ground substance, and integrins

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3
Q

how are cells able to communicate with each other

A

by secreting chemical regulators into the extracellular environment

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4
Q

how can it be said that cells have a give-and-take relationship with their extracellular environment

A

cells receive nourishment from it, and they release wastes to it

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5
Q

what are fluid-filled compartments separated by

A

epithelial membranes

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6
Q

where is transport occurring between intracellular and extracellular environments

A

across the plasma membrane

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7
Q

why are membranes important for transport

A

acts as a regulator for the passage of fluid b/w compartments (most made up of water)

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8
Q

why is water an important solvent?

A

it can interact with large (proteins) and small (inorganic ions, sugars, amino acids), molecules

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9
Q

draw a flowchart of the body fluid compartments

A

total body water splits into intracellular (67%) and extracellular fluids; extracellular fluid splits into interstitial fluid (80%) and blood plasma

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10
Q

compare intracellular and extracellular fluids

A

intra: fluid inside cells; protein and K+ rich

extra: fluid outside cells; few proteins and Na+ rich

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11
Q

compare interstitial fluid and blood plasma

A

ISF: fluid that surrounds cells except blood cells in circulatory system; few proteins

blood plasma: fluid that surrounds blood cells in circulatory system; protein rich

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12
Q

why is compartmentalization important

A

each cell can make exchanges b/w internal and external cellular environments; body systems can transfer material which helps with maintaining homeostasis

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13
Q

what is total body water

A

total volume of fluid in all compartments

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14
Q

what type of permeability does the plasma membrane have

A

selective

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15
Q

Why is the plasma membrane permeable to small, uncharged polar molecules even though the interior of the membrane is hydrophobic?

A
  • they move between gaps that perform between fatty acid tails of membrane (dynamic structure with constant ‘moving’)
  • kinetic barrier is not great enough to prevent diffusion from occurring on a time scale relevant to that of living systems
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16
Q

Is the plasma membrane permeable to nucleic acids, proteins and structural molecules?

A
  • no
  • large in size
  • DNA has - charge
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17
Q

moving substances across the plasma membrane can be categorized in different ways. list them

A

carrier-protein requiring: carrier-meditated transport, non-carrier-meditated transport

energy requiring: active, passive, bulk transport

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18
Q

describe passive transport

A

spontaneous, no cell energy needed, “downhill” transport along conc gradient

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19
Q

what are the types of passive transport

A

osmosis, simple diffusion, facilitated diffusion (channel or carrier mediated)

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20
Q

explain the process of simple diffusion; what is the net movement

A

random ‘mixing’ of particles from one location to another (physical separation not necessarily needed); net movement is from higher solute concentration to lower solute concentration

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21
Q

define mean diffusion time

A

the average time it takes for a solute to diffuse

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22
Q

what can transport through simple diffusion through the plasma membrane. provide some examples

A
  • small, uncharged (non-polar) lipid soluble molecules pass easily like O2, CO2, steroid hormones, ethanol, urea
  • charged ions can pass through using ion channels
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23
Q

explain gas exchange in simple diffusion

A

net diffusion of O2 into cells and CO2 out of cells due to concentration gradients

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24
Q

what are the factors affecting rates of diffusion

A

magnitude of driving force, membrane surface area, membrane permeability, temperature

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25
Q

what do we mean by the magnitude of driving force

A

how large the concentration gradient is

26
Q

what is one way membrane surface area can be increased

A

thru microvilli

27
Q

explain the process of osmosis

A

passage of water through plasma membrane by aquaporins from low to high solute concentration

28
Q

what are aquaporins and where are they found

A

water membrane channels; found in kidneys, eyes, lungs, salivary glands, brain

29
Q

what are the requirements for osmosis

A
  • solute concentration difference on either side of a membrane permeable to water
  • membrane must be impermeable to solute, otherwise concentration difference won’t be maintained
30
Q

what are osmotically active solutes

A

those that cannot cross the membrane but can permit osmosis

31
Q

describe the net movement of water for osmosis

A

from more dilute (low solute) to less dilute (high solute)

32
Q

describe the movement of water if aquaporins were not present

A

extremely slow

33
Q

describe channel-mediated transport

A
  • needs transmembrane protein that functions like a passageway or pore
  • substance-specific
  • some channels always open, some are gated
  • most membrane channels are ion channels
34
Q

what does a transmembrane protein refer to

A

protein embedded into membrane and spans it

35
Q

describe gated ion channels

A

can open based on conformational shape change due to physiological stimuli (e.g. chemical regulator binding), otherwise remains closed

36
Q

compare aquaporins and ion channels

A

aq: highly selective (water only), gated, have different classes

ion chan: have leak channels and gated channels

37
Q

what are ion leak channels

A

channels that are open all the time (non-gated)

38
Q

explain the process of carrier mediated transport

A
  • passive transport (no ATP)
  • high to low conc
  • needs specific carrier-mediated proteins for each transported material
  • conformational shape change with binding to “swing” material to low conc. side
39
Q

what is the name(s) of the specific glucose carriers in central nervous system

A

GLUT1 and 3

40
Q

where is carrier GLUT 2 typically found

A

pancreatic beta cells, hepatocytes (liver cells)

41
Q

where is carrier GLUT 4 typically found

A

fat tissue, skeletal muscle

42
Q

what are the properties of carrier-mediated transport

A

specificity, competition, saturation

43
Q

what do we mean by competition in carrier-mediated transport

A

some molecules with compete with each other for the binding sites on a carrier since they are so similar (EX amino acids)

44
Q

what do we mean by saturation in carrier-mediated transport

A

a limit to the rate of transport (to a point)

45
Q

describe the transport maximum

A

the plateau region of saturation effects on carrier mediated transport, in which any factors above this will not make any difference to the rate of transportation

46
Q

explain the process of active transport

A
  • movement of ions and molecules against their concentration gradient
  • nonspontaneous (needs energy)
  • movement is uphill and needs a “pump”
47
Q

what are the types of active transport

A

primary and secondary

48
Q

explain the primary active transport process using the Ca +2 pump example

A
  • Ca+2 inside cells binds to carrier protein site facing inside cell
  • ATP hydrolyzed into ADP + P which bind to pump
  • release of ADP causes conformational shape change releasing Ca+2 to extracellular side
  • P releases from pump to trigger carrier to change back into original shape and let Ca+2 bind again
  • this continues as long as there is ATP
49
Q

how many Na+ and K+ are moving into and out of the cell in 1 primary active transport cycle; what enzyme does this

A

ATPase enzyme pumps 3 Na+ out of the cell and 2 K+ into the cell

50
Q

What are the 3 functions of the sodium/potassium pump

A

1) Provides energy for coupled transport of other molecules
2) Produces electrochemical impulses in neurons and muscle cells
3) Maintains osmolality of cells

51
Q

explain the process of secondary active transport

A
  • uses energy from an electrochemical gradient or concentration gradient previously created by primary active transport
  • Involves two molecules or ions
52
Q

describe cotransport

A

both substances move in same direction

53
Q

describe countertransport

A

both molecules move in opposite directions

54
Q

how is the SGLT pump able to transport glucose against its concentration gradient

A

via energy from sodium movement along its concentration gradient

55
Q

the small intestine has what type of sodium coupled glucose transporter; the ratio of sodium:glucose

A

SGLT 1; 2:1

56
Q

the kidneys have what type of sodium coupled glucose transporter; the ratio of sodium:glucose

A

SGLT 2; 1:1

57
Q

ICF/ECF composition differs, but ICF composition remains relatively steady. Why don’t intracellular concentrations change?

A

due to leak channels allowing for passive transport of materials back in to their originating spots (e.g. K passively diffuses back out despite normally being pumped in)

58
Q

define exocytosis; what is it used for; energy?

A
  • fusion of a vesicle with the plasma membrane, needs ATP
  • used for large molecule secretion, like proteins, hormones, and neurotransmitters
59
Q

define endocytosis; what is it used for

A

cells engulf large substances like cholesterol into a vesicle (usually triggered by plasma membrane protein and transport protein interacting) and bring it inwards

60
Q

explain how a molecule moves in facilitated diffusion

A

down (along) its concentration gradient with the assistance of a protein carrier molecule, and no energy is required

BIOL 2010 (18 decks)

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