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pps 911 > Membrane Structure > Flashcards

Membrane Structure Flashcards

1
Q

What are five functions of the cell?

A

Cell metabolism, energy use, synthesis of molecules, communication, reproduction/inheritance

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2
Q

What is membrane potential?

A

The difference in charge across the membrane

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3
Q

Is the outside of the membrane positively or negatively charged relative to the inside?

A

Outside positive relative to inside

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4
Q

Glycocalyx

A

Carbohydrates, glycolipids, and glycoproteins combined on outer cell surface

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5
Q

Transmembrane Protein Functions

A

Transport, reception, facilitates signaling

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6
Q

What are three membrane lipids?

A

phosphoglycerides, sphingolipids, cholesterol

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7
Q

What are the four main types/functions of membrane proteins?

A

adhesion, receptors, transporters, pores

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8
Q

How thick is the lipid bilayer?

A

3-5 nm

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9
Q

What interactions contribute to the stability of the lipid bilayer?

A

Hydrophobic interactions of lipophillic tails, van der Waals interactions between lipophillic chains

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10
Q

Where are sphingolipids commonly found?

A

CNS (central nervous system) molecules

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11
Q

What are some factors that increase fluidity of the membrane?

A

Degree of saturation (more double bonds makes kinks in nonpolar tails, which decreases the van der Waals reactions and decreases the surface area of tails touching) and Less Cholesterol (less interactions with tails, more fluidity)

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12
Q

What are some factors that decrease membrane fluidity?

A

Longer nonpolar C-C chains (stronger interactions), More Cholesterol (more interactions, more rigid membrane)

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13
Q

What is the purpose of lipid rafts?

A

Facilitate communication between inside and outside of cell

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14
Q

What do flippases do?

A

Participate in rearrangement of membrane composition (“flip” back and forth)

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15
Q

Integral proteins

A

extend deep into membrane, usually go all the way through, can form channels

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16
Q

Peripheral proteins

A

attach to integral proteins on either the inside or outside of cell bilayer

17
Q

Why do integral proteins have both hydrophillic and hydrophobic domains?

A

So the protein can interact with all parts of the membrane and stay in a fixed position

18
Q

How are lipid anchored proteins bound to the lipid?

A

With covalent bonds

19
Q

What are marker molecules?

A

allow cells to identify each other (necessary b/c only one type of peptide bond), examples are glycoproteins and glycolipids bound to protein, as well as carbohydrate chains

20
Q

These proteins are secreted and loosely associated with cells and extracellular matrix

A

proteoglycans

21
Q

What are the functions of glycoproteins?

A

Protection, immunity, transplant compatibility, structural integrity and adhesion, fertilization, development

22
Q

These attachment proteins attach cells to other cells

A

cadherins

23
Q

Integrins

A

Integral proteins that attach to extracellular molecules (sometimes allow communication), link cytoskeleton to extracellular matrix, cluster to form focal adhesions

24
Q

Tight junctions

A

seal neighboring cells together to prevent molecules from leaking between them

25
Q

Adherens junctions

A

join actin bundles in neighboring cells together

26
Q

Desmosomes

A

join intermediate filaments in neighboring cells together

27
Q

Gap junctions

A

allows small water-soluble ions and molecules to pass from cell to cell

28
Q

Hemidesmosomes

A

anchors cell to the basal lamina

29
Q

In transport proteins, does the hydrophobic or hydrophillic region faces inward (toward the channel)

A

Hydrophillic

30
Q

These channels are always open and keep the plasma membrane permeable when the membrane at rest

A

nongated ion channels

31
Q

These channels are opened and closed by certain stimuli

A

gated ion channels

32
Q

What are the three forms of carrier proteins (transporters)?

A

uniporters (move one particle), symporters (move two particles in same direction at same time), antiporters (move two particles in opposite directions at same time)

33
Q

For ATP-powered transport proteins, the rate of transport depends on which two factors?

A

the concentration of the substrate and the concentration of ATP

34
Q

Receptor proteins serve what main purpose?

A

an intercellular communication system

35
Q

What is the difference between channel proteins and carrier proteins?

A

Carrier proteins have binding sites and must change shape to transport substances, while channel proteins just provide a passageway for substances

36
Q

They act to catalyze reactions at outer/inner surface of the plasma membrane

A

Enzymes

pps 911 (6 decks)

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