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BIOL 1020 > Membranes- lecture #8 > Flashcards

Membranes- lecture #8 Flashcards

1
Q

what does the plasma membrane consist of?

A

lipid bilayer (phospholipids) that is selectively permeable

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2
Q

why are plasma membranes described as a fluid mosaic?

A

fluid: proteins able to move in the membrane
mosaic: proteins floating within the membrane

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3
Q

what prevents fatty acids from packing closely together? why is it good for them not to pack closely together?

A

double bonds prevent them from packing closely
keeps the membrane fluid

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4
Q

what does the plasma membranes allow to pass through it?

A

hydrophilic molecules, nutrient uptake and waste removal

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5
Q

what happens to phospholipids as the temperature decreases?

A

phospholipids solidify into position, more unsaturated (kinks in tails)

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6
Q

what happens to phospholipids as the temperature increases?

A

phospholipids are more active and are more saturated (no kinks in tails)

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7
Q

what is the membrane always wanting?

A

to be semi- fluid, regardless of the temperature

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8
Q

at increased temperature what is cholesterol doing?

A

cholesterol hinders phospholipid movement and keeps the membrane from melting

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9
Q

at decreased temperature what is cholesterol doing?

A

cholesterol interferes with close packing and keeps the membrane from freezing

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10
Q

what are the 2 types of proteins in the membrane

A

integral protein and peripheral protein

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11
Q

what are integral proteins?

A

permanent part of the membrane
normally transmembrane proteins
some are lipid anchored (only goes half through the lipid bilayer)

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12
Q

what are peripheral proteins?

A

temporarily associated with membrane
loosely bound to the surface of the cell

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13
Q

6 primary functions of membrane proteins

A

stronger membrane framework
tight membrane junctions
transport
identification tags
function as enzymes
function as receptors

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14
Q

what is an example of a cell identification tag

A

glycoproteins

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15
Q

why do membrane proteins hook together?

A

protects against bacteria

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16
Q

what is signal transduction?

A

binding of the messenger triggers a series of events that turn on or off processes occurring within the cell

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17
Q

what does cellular recognition do?

A

allows removal of foreign cells from the body

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18
Q

what is a oligosaccharide?

A

carbohydrate that is less then 15 sugar units

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19
Q

what is a glycolipid and a glycoprotein?

A

carbohydrate and a lipid
carbohydrate and a protein

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20
Q

what is normally involved in cell identification?

A

carbohydrates

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21
Q

what are blood types the result of?

A

membrane carbohydrates attached to proteins. this distinguishes your blood.

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22
Q

how do carbohydrates vary?
_______,_______,________

A

from species to species
from different individuals of the same species
from cell to cell

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23
Q

what is osmosis?

A

the movement of water across a semipermeable membrane (passive process)

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24
Q

what is the membrane permeable to and not permeable to in osmosis?

A

permeable to water but not to solute

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25
when will osmosis stop?
when equilibrium is reached
26
water will always move from areas of ______ solute concentration to areas of ______ solute concentration
low solute concentration to high solute concentration
27
what is tonicity?
the ability of solution to cause a cell to gain or lose water
28
what is an isotonic?
no net movement stays the same size animal cell is immersed in solution that has equal solute concentration to the cell
29
what is a hypotonic?
net movement of water into the cell expands and eventually bursts animal cell is immersed in solution that has lower solute concentration then the cell
30
what is hypertonic?
net movement of water out of the cell dehydrate and shrivel animal cell is immersed in solution that has higher solute concentration then the cell
31
what is osmolysis?
net movement of water into the cell causing it to expand and eventually burst
32
what is osmoregulation?
plant and animal cells must regulate water gain/loss in order to survive
33
what type of environment do organisms that lack a cell wall live
isotonic environment
34
what will organisms have that live in hypotonic environments?
altered membrane permeability to water (slow movement of water into the cell) have pumps to force water out of the cell
35
what is turgor pressure?
counterforce on the cell, the cell will be firm once this force is applied
36
in isotonic environments how will a plant immersed in rain water react?
the cell will be limp
37
what is plasmolysis?
cell membrane pulls away from the cell wall causing shrinking, wilting and death
38
what ions need proteins in order to cross the membrane?
strongly charged ions (polar) need proteins
39
what factors affect diffusion rate?
size, shape and polarity
40
what is able to diffuse across the membrane easily from high to low concentration
O2, CO2 and hydrocarbon molecules
41
what would happen if we didn't have membrane proteins?
we would die because they make diffusion faster
42
what happens to passive transport when temperature is increased?
faster moving molecules
43
is passive transport spontaneous or non-spontaneous?
spontaneous
44
what are the 2 types of membrane transport and what do they do?
channel proteins (have a hydrophilic channel through the membrane) carrier proteins (physically grab and escort specific material through the membrane)
45
what kind of process is facilitated diffusion and does it require energy?
passive process doesn't require energy
46
what stimuli do channel proteins open for
electrical, chemical, mechanical stimuli
47
what transport does facilitated diffusion use?
channel proteins and carrier proteins
48
are transport proteins always specific what increases the speed of facilitated diffusion of a substance?
YES. the more transport proteins there are for a particular solute the faster diffusion rate will be
49
what uses facilitated diffusion to cross the membrane?
many sugars, amino acids and sometimes water
50
what does water use to diffuse across the membrane at a reasonable rate?
aquaporins (protein channels)
51
what is the difference between carrier proteins in facilitated diffusion and carrier proteins in active transport?
carrier proteins use energy in active transport because its moving molecules from low to high concentration
52
what proteins are involved in active transport?
carrier proteins only
53
how do we get energy to do active transport?
energy is harvested from the high to low concentration process.
54
what are the steps of active transport?
solute binds to a specific site on protein ---> ATP molecule transfers a phosphate to the transport protein ---> protein changes shape ---> releases protein by distorting itself ---> protein resets to its original shape
55
what is more positive or negitive, the cytoplasm or the extracellular
cytoplasm is more negitive, extracellular is more positive
56
the cytoplasm and extracellular being opposite charges creates what?
a membrane potential
57
what is a electrochemical gradient?
when the (-) cytoplasm functions to pull cations (+) into the cell
58
what 2 forces drive the movement of the solute?
concentration difference (chemical force) charge difference (electrical force)
59
what is an electrogenic pump main function?
to pump Na ions out of the cell and K+ ions into the cell
60
what do electrogenic pumps use to transport Na and K ions across the cell membrane?
uses ATP
61
what do electrogenic pumps create?
charge seperation
62
how is energy stored?
as a voltage difference and the gradient can be used to perform work and synthesise ATP
63
what do co-transporters do?
couple the movement of one material down its concentration gradient (energy releasing) to the movement of another material up its concentration gradient (energy required)
64
what requires bulk transport?
larger molecules require bulk transport to get into the cell
65
what 2 forms does bulk transport use?
exocytosis and endocytosis
66
what is the process of exocytosis? from golgi
molecules bud off golgi apparatus into transport vesicles, vesicles travel to the plasma membrane, then fuse to the plasma membrane, expells vesicular contents into the extracellular, vesicular membrane becomes part of the plasma membrane
67
what uses exocytosis?
insulin, neurotransmitters and large proteins
68
what does endocytosis do?
brings large molecules into the cell
69
what 3 types of endocytosis are used and why are there 3 types?
depends on the size and nature of the material to be ingested. phagocytosis, pinocytosis, receptor mediated endocytosis
70
how does phagocytosis work?
cell engulfs a large molecule, pseudopods wrap around the molecule, wrapped particle buds off creating a vacuole, vacuole fuses with a lysosome, digestive enzymes breakdown the contents of the vacuole
71
what dos pinocytosis ingest instead of large molecules?
ingests fluid
72
is pinocytosis specific?
very non- specific
73
how does receptor mediated endocytosis work?
molecules bind to specific receptors on the plasma membrane, protein receptors deepen into the cell, creates a coated vesicle
74
is receptor mediated endocytosis specific?
highly specific process
75
when is receptor mediated endocytosis used?
when theres a specific need for that molecule

BIOL 1020 (16 decks)

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