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Cell Bio > Lecture 9 - Exam > Flashcards

Lecture 9 - Exam Flashcards

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Biology 101 flashcards
1
Q

What is the purpose of proteins embedded in membranes?

A

Water channels, ion channels, receptors and cell attachment

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2
Q

What are the different types of membrane proteins?

A

Transmembrane, integral, and peripheral

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3
Q

What are the components of the transmembrane proteins?

A

Extracellular domain, transmembrane spanning domain, and intracellular/cytosolic domain

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4
Q

What are integral membrane proteins?

A

Embedded in membrane, but do not span it

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5
Q

What are peripheral membrane proteins?

A

Proteins on either the intra- or extracellular domains that can interact with the other proteins

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6
Q

What is an additional function of anchoring proteins that interact with membrane proteins?

A

Cell signaling

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7
Q

What are caveolae? And what do they play an important role in?

A

Flask shaped invaginations on the cell surface - type of membrane raft - regulate expression of receptors and transporters by controlling how many are present on the surface of cells

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8
Q

What is the order of membrane rafts?

A

Ordered phase that float in sea of poorly ordered lipids

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9
Q

What can membrane fluidity affect?

A

Function and organization of rafts - spatially organize signaling molecules to promote kinetically favorable interactions necessary for signal transduction - can also conversely separate signaling molecules inhibiting interactions and dampening signaling responses

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10
Q

What is the membrane permeable to? and what kind of transport do these molecules use?

A

Gases and small uncharged polar molecules - passive diffusion

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11
Q

What is the membrane impermeable to?

A

Large, uncharged polar molecules, ions, charged polar molecules (hydrophilic) - need transporters

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12
Q

What is the partition coefficient?

A

K, ratio of solute concentration in oil: solute concentration in water - K>1 is more lipid soluble and K<1 is more water soluble

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13
Q

What is LIpinskin’s Rule of Five?

A

In the absence of a transporter, diffusion across a membrane can not have more than 5 hydrogen bond donors (N or O with one or more hydrogen atoms), not more than 10 hydrogen bond acceptors (N or O), molecular mass no greater than 500 daltons, and an octanol-water partition coefficient log P not greater than 5 - must be transported if it doesn’t meet these rules

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14
Q

What are active transporters?

A

ATPases that require energy to move things against a gradient

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15
Q

What are secondary active transporters? And what is another name for it?

A

Facilitated diffusion - Require another molecule to work and the other molecule is driven by an active transporter

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16
Q

What are proteins that move phospholipids from one side of a bilayer to the other called? Does it require energy?

A

Flippases, can require energy or be passive - but reduces half time for the movement significantly

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17
Q

What are the classes of ATPase active transport pumps?

A

P-class, F- and V- class, ABC superfamily

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18
Q

What are P-class pumps? and where are they found?

A

A type of active transporter - proton pumps - H+K+ pump in the stomach gives acidic environment when parietal cells produce HCl and pumps H in, H+ pump on PM of plants, fungi, bacteria and as Na+K+ pump on PM of euk, Ca2+ pump in PM of all euk cells and sarcoplasmic reticulum

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19
Q

What drug inhibits P class pumps?

A

Esomeprazole - Nexium brand name for stomach (HK), oubain and digoxin (NaK)

20
Q

What is the ABC superfamily of active transporters? and where are they found? What is an example?

A

Large family of pumps that move hydrophobic substrances - prevent xenobiotics from entering - normally move cholesterol and phospholipids out, inducible expression - found on bacterial and mammalian PM - p-glycoprotein is an example and is part of the multi-drug resistance family - MDR1

21
Q

What is the V class of active transporters? and where are they found?

A

Only pump Hydrogen ions - found on vacuolar membranes, endosomal and lysosmal membranes, and PMs of osteoclasts and kidney tubules

22
Q

How does the sodium-potassium pump work?

A

It brings two potassium ions in and three sodium ions out by undergoing phosphorylation conformational change to create an electrical potential that can be used to do work to move co-transporters

23
Q

What causes muscle contraction? And what blocks the channel?

A

Depolarization of the sarcoplasmic reticulum activates the ryanodine channel to release Ca++ causing contraction - blocked by dantrolene - caffeine can reduce the threshold for calcium release

24
Q

What is an important function of a v-class proton pump? And what can this activity lead to?

A

Maintains acidity inside of organelles (keeps pH inside lysosomes at 4.5 ) - trigger function to create a gradient that can drive co-transport (VMAT - vesicular monoamine transporter)

25
Q

What is Marble bone disease and Albers-Schonberg and what causes is?

A

AKA Osteopetrosis - genetic disorder in which bones harden and become denser and is a result of a V-pump mutation or channelopathy

26
Q

What is ion trapping?

A

V-class pumps are able to trap NTs inside of their vesicle through use of the VMAT

27
Q

What inhibits VMAT and where are VMATs found?

A

VMAT2 found on synaptic vesicles inhibited by reserpine and tetrabenazine
VMAT1 found in adrenal medulla

28
Q

What does ABC superfamily stand for?

A

ATPase Binding Cassette

29
Q

Which pumps cause issues with cancer treatment and those involved in the BBB and GI brush border?

A

ABC superfamily - give multi drug resistance

30
Q

What drugs did MDR-1 become resistant to?

A

Vincristine - Oncovin brand name - aka leurocristine - a mitotic inhibitor used in cancer chemotherapy

31
Q

What inhibits p-glycoprotein?

A

Favinoids naringin and naringenin

32
Q

What are some characteristics of transport proteins?

A

Faster than passive diffusion,partition coefficient K is irrelevant, it is saturable, it is specific and it is subject to inhibition by competition at binding site

33
Q

What is a uniporter and what is a common example?

A

Transfer one molecule down a concentration gradient, glucose transporters

34
Q

What are symporters and antiporters?

A

Secondary active transporters that move substances against concentration gradients by taking advantage of a molecule that is moving down its gradient - sodium dependent glucose transporters - VMAT can act as an antiporter

35
Q

What is Donnan Equilibrium?

A

Cell contains more negative proteins and so ion distribution distributes accordingly

36
Q

How can ion channels be gated?

A

Ligand, voltage, pH, oxygen tension

37
Q

What can enhance or inhibit the effects on ligand gated ion channels?

A

Multiple regulator sites - not the same for everyone

38
Q

What can facilitate the transport of water through membranes and what is it regulated by?

A

Aquaporins - prevent ions from crossing - regulated by ADH production form pituitary

39
Q

What is tonicity?

A

Amount of solute in the extracellular space

40
Q

What is hypotonic and hypertonic?

A

Hypotonic - less solute outside than inside
Hypertonic - more solute outside than in
Moves from low to high

41
Q

What is oncotic pressure?

A

AKA colloid osmotic pressure - A form of osmotic pressure exerted by proteins (albumin) in a blood vessel’s plasma that tends to pull water into the circulatory system

42
Q

Do transport proteins exist by themselves?

A

No - they must be coupled with other transporters to ensure pH, osmotic, oncotic, concentration and electrochemical gradients

43
Q

How do cell’s maintain pH gradient?

A

Different antiporters that neutralize to maintain proper pH
Na/H antiporter becomes more active to pump more H ions out if pH becomes too acidic
Bicarb/Cl antiporter does as well

44
Q

How does the NaK pump create action potential? And what is the rate of change dependent on?

A

Sodium channels open and sodium enters cell –> Potassium channels open and potassium begins to leave cell (raising potential) –> Sodium channels close –> Rest of potassium leaves cell (lowering potential and creating overshot) –> Potassium channels close and excess potassium diffuses away - dependent upon density of channels

45
Q

What are graded potentials?

A

Depolarizations that do not reach adequate voltage change or threshold potential to activate voltage gater chanels

Cell Bio (9 decks)

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