Chapter 7 Flashcards

1
Q

Aquaporin

A

A membrane protein that enables water molecules to pass through the membrane.

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2
Q

Amphipathic

A

Has both a hydrophilic region and a hydrophobic region

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3
Q

Fluid mosaic model

A

The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.

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4
Q

A membrane is held together primarily by ____

A

Hydrophobic interactions

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5
Q

The membrane remains fluid to a lower temperature if it is rich in phospholipids with ….

A

Unsaturated hydrocarbon tails.

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6
Q

Cholesterol can be thought of as a…

A

Fluidity buffer for the membrane because it resists changes in membrane fluidity that can be caused by changes in the temperature.

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7
Q

Like a tile mosaic, a membrane is…

A

A collage of different proteins, often clustered together in groups, embedded in the fluid matrix of the lipid bilayer.

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8
Q

Proteins determine most of the membrane’s functions.

A

True

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9
Q

Integral proteins

A

Penetrate the hydrophobic interior of the lipid bilayer. Transmembrane proteins span through the entire membrane.

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10
Q

The hydrophobic interior of an integral protein consists of…

A

Non polar amino acids usually coiled into alpha helices

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11
Q

Peripheral proteins

A

Are not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins.

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12
Q

Six major functions performed by proteins of the plasma membrane

A

Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and ECM

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13
Q

How membrane sidedness arises:

A

The asymmetrical arrangement of proteins, lipids, and their associated carbohydrates in the plasma membrane is determined as the membrane is being built by the ER and Golgi apparatus.

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14
Q

What molecules can cross the lipid bilayer of the membrane easily?

A

Non-polar, hydrophobic, molecules

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15
Q

The hydrophobic interior of the membrane impedes direct passage through the membrane of….

A

Ions and polar molecules, which are hydrophilic

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16
Q

Channel proteins

A

-Transport proteins
Have a hydrophilic channel
Ex. Aquaporins

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17
Q

Carrier proteins

A

-Transport protein
Hold onto their passengers and change shape in a way that shuttles them across the membrane.

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18
Q

The concentration gradient itself represents ___________ and drives diffusion

A

Potential energy

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19
Q

Tonicity

A

The ability of a surrounding solution to cause a cell to gain or lose water.

20
Q

Non penetrating solutes

A

Concentration of solutes that cannot cross the membrane.

21
Q

If there is a higher concentration of non-penetrating solutes in the surrounding solution,

A

Water will tend to leave the cell, and vice versa

22
Q

In a solution that is hypertonic to the cell,
Hypertonic means

A

More non-penetrating solutes
-the cell will lose water

23
Q

A solution that is hypotonic to the cell means

A

Less non-penetrating solutes
-Water will enter the cell

24
Q

A cell without rigid cell walls can tolerate…

A

Neither excessive uptake nor excessive loss of water

25
Q

Osmoregulation

A

The control of solute concentrations and water balance.

26
Q

Cell wall helps maintain water balance

A

True

27
Q

Healthy state for most plant cells:

A

Turgid in a hypotonic solution

28
Q

Ion channels

A

Channel proteins that transport ions

29
Q

Many ion channels function as ________

A

Gated channels

30
Q

Gated channels

A

Open or close in response to a stimulus

31
Q

Facilitated diffusion is considered passive transport because the solute is moving down its concentration gradient, a process that requires no energy.

A

True

32
Q

The transport proteins that move solutes against their concentration gradients are all _________

A

Carrier proteins

33
Q

Sodium-potassium pump

A

Exchanges Na+ for K+ across the plasma membrane of animal cells.

34
Q

All cells have voltages across their plasma membrane

A

True

35
Q

Voltage

A

Electric potential energy

36
Q

Membrane potential

A

The voltage across a membrane
Ranges from about -50 to -200 millivolts (mV)

37
Q

The cytoplasmic side of the membrane is negative in charge relative to the extracellular side

A

True

38
Q

The membrane potential favors the passive transport of cations into the cell and anions out of the cell because the inside of the cell is negative compared with the outside

A

True

39
Q

Two forces drive the diffusion of ions across a membrane

A

A chemical force (the ion’s concentration gradient)
An electrical force (the effect of the membrane potential on the ion’s movement)

40
Q

Electrochemical gradient

A

The combination of forces acting on an ion

41
Q

An ion diffuses down its …

A

Electrochemical gradient

42
Q

Electrogenic pump

A

A transport protein that generates voltage across a membrane

43
Q

Proton pump

A

-electrogenic pump
Actively transports protons (H+) out of the cell.

44
Q

Exocytosis

A

The process where the cell secretes certain molecules by the fusion of vesicles with the plasma membrane

45
Q

In endocytosis,

A

The cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane.

46
Q

Three types of endocytosis

A

Phagocytosis
Pinocytosis
Receptor-mediated endocytosis

47
Q

Ligands

A

A term for any molecule that binds specifically to a receptor site on another molecule