Exam 1: Ch 4 Notes Flashcards

1
Q

if you change size you change

A

surface area to volume ratio

strength to weight ratio

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2
Q

organisms of different sizes face the same challenge and have different solutions due to the laws of physics

A

pond skater vs hovercraft on water

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3
Q

diffusion only works for some sizes

A

high surface area to volume ratio

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4
Q

3 big environmental factors

A

temperature

oxygen

access to water

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5
Q

temperature environment example

A

tropical fish (22-29°C) vs polar fish (-1.9°C)

0°C is freezing and ice crystals expand and puncture cells

ice fish developed antifreeze proteins in cells that wrap around ice crystals to prevent growth

disadvantage: ice crystals don’t thaw above freezing

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6
Q

6°C paradigm

A

cool tropical fish to 6°C and they die

heat ice fish to 6°C and they die too

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7
Q

5 thermoregulation adaptions

A

insulation

circulatory

cooling by evaporative heat loss

adjust metabolic heat production

change behavior

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8
Q

oxygen environment example

A

if you live at altitude you have less O2 than at sea level

evolutionary adaptions of other animals vs. humans

geese vs. humans

tibet vs. peru

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9
Q

water environment example (presence vs. absence)

A

osmotic challenge

desert beetle has ridges that allow water to condense and drip toward mouth

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10
Q

to have viable life you must have…

A

controlled chemical reactions

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11
Q

for controlled chemical reactions you must have…

A

a controlled environment… in cells this is the phospholipid bilayer (10-20nm)

membrane regulates influx and efflux

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12
Q

what forces are at play in cell membranes

A

permeability

concentration gradients

electrical charge

diffusion

active pumping

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13
Q

what level of permeability do cell membranes exhibit

A

semi-permeable

prevents large molecules (proteins), charged molecules or ions, and hydrophilic substances from crossing

water, oxygen, and fat soluble molecules can cross

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14
Q

what does the fluid mosaic membrane model tell us

A

membranes are dynamic and complex

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15
Q

the properties of the membrane depend on…

A

the properties of the lipids

saturated: no db so better packing
unsaturated: db kinks less packing

cholesterol stiffens and strengthens the membrane

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16
Q

what enables self repair between fatty acid tails in membranes

A

van der waals forces

these forces also allow geckos to climb smooth surfaces

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17
Q

integral proteins

A

proteins in the membrane must have hydrophobic aas in the membrane and polar aas outside the membrane

mostly alpha helices

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18
Q

diffusion

A

random movement from areas of high concentration to areas of low concentration until equilibrium is reached

movement in both directions does not stop at equilibrium, the net movement is just 0

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19
Q

what affects speed of diffusion

A

temperature (speed)

size of the concentration gradient (speed)

membrane properties

properties of the crossing molecule

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20
Q

membrane permeability

A

rate at which a substance passively crosses the membrane at a set temp etc.

greater permeability = greater flux across membrane

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21
Q

permeability constant equation

A

Pm = (Dm)(K) / x

Dm = diffusion constant

K = partition coefficient

x = thickness of the membrane

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22
Q

partition coefficient

A

indication of ability to dissolve in membrane

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23
Q

how can the permeability of a membrane change?

A

cell opens ion or aquaporin channels

24
Q

diffusion doesn’t factor in…

A

charge

active pumping

25
as cell membrane thickens, diffusion is affected how
takes more time
26
osmosis
movement of water across membrane from areas of highest water purity to lower water purity (water + dissolved substances) at equilibrium net movement of water is 0 b/c hydrostatic pressure balances osmotic pressure
27
osmotic pressure
pi = RTC R = gas constant T = temp C = solute concentration
28
osmolarity
theoretical comparison iso is equal amounts of 1mM NaCl hypo (lower osmotic pressure, fewer solutes, more pure H2O) hyper (higher osmotic pressure, more solutes, less pure H2O) moves from hypo to hyper
29
tonicity
cell based comparison
30
tonicity example
sea urchin egg isotonic to seawater isoosmotic in NaCl isoosmotic CaCl2, but hypotonic in CaCl2 b/c cell more permeable to Ca2+ (water moves in to swell cell)
31
Na diffusion permeability example
cell membrane slightly permeable to Na, which has a higher [ ] outside the cell movement of Na is into cell (high to low) consequences: higher osmotic pressure, H2O swells solution: pump Na out of cell using ATP
32
prove presence of Na pump
metabolic inhibitor lowers ATP pump slows and cells burst b/c buildup of Na inside cell causes H2O to follow
33
how do plant cells and bacterial cells withstand high pressure buildup?
cell wall
34
mechanism of secondary active transport
uses concentration gradient or electrical gradient to move other molecules against their gradients
35
why does rate of channels, pumps, carriers taper off?
at high [substrate] all channels, pumps, carriers are saturated carriers saturate faster
36
nystatin
an antibiotic that forms channels in a membrane H2O, urea, and Cl- allowed through, but not cations if using a patch, no need to puncture membrane
37
inject aquaporin RNA into frog oocyte
expresses channels for H2O water moves into oocyte, which has a concentrated cytoplasm
38
carrier proteins exhibit...
selectivity
39
coupled carriers
symporters and antiporters use [ ] gradient of one to power movement of the other
40
cystic fibrosis and Cl- channel mutation
normally CF channel lets Cl- out of cell (slippery normal mucous) in mutation the Cl- doesn't move out (sticky mucous)
41
Na/K ATPase
pump that uses ATP to create a [ ] gradient of low Na in cell and high K in cell 3 Na out, 2 K in creates net negative resting potential inside cell
42
Na/K ATPase steps
bind 3 Na+ form cytosol phosphorylation by ATP changes conformation Na+ released in extracellular fluid, 2 K+ binds dephosphorylation changes conformation 2 K+ released in cytosol
43
alanine/Na symporter
alanine moves against concentration gradient, Na moves down concentration gradient depends on Na/K ATPase to maintain Na gradient if excess Na inside cell, symporter moves alanine out
44
antiporter example
Na in, Ca out
45
active transport summary
ATP required to move substances against [ ] gradient highly selective some pumps perform electrical work selectively inhibit pumps (ouabain inhibits Na/K ATPase)
46
epithelial sheets
polarity of cells and location of pumps, channels, and transporters regulates movement
47
different membranes/regions of the cell can have different ______
selectivity ex. voltage gated Na channel lets Na and Li through Na/K ATPase lets Na through but not Li
48
how is selectivity achieved?
size, shape, charge energy of dehydration interaction of channel charges with ions
49
endocytosis
protein clathrin coats membrane, ligand binds, invagination vesicle fuses with other cellular membrane component, clathrin recycled recycles membrane added from exocytosis
50
exocytosis
out of cell ex. neurotransmitter release
51
gap junction stucture
1/2 of structure made by cell 1, other half by cell 2 6 proteins --> 1 connexon + 1 connexon = gap junction
52
gap junction purpose
direct electrical coupling between cells for ions, ATP, small molecules, 2nd messengers
53
gap junction test
inject dye of varying size and see if it diffuses through the cells
54
tight junctions
seal gap between cells to form an impermeable, intact sheet things cant move inbetween individual cells, so must move through the cell bodies allows cells to regulate what moves through
55
intermediate junctions
allow more rapid flow b/c moving through cell takes times can move on [ ] gradient