Chapter 7: Membrane Structure and Function Flashcards

1
Q

Two types of cellular membrane proteins

A

Integral (transmembrane)

Peripheral (does not go through the bilayer

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2
Q

Amphipathic molecules?

A

Hydrophobic and hydrophilic components

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3
Q

Describe the movement of phospholipids across the membrane

A

Phospholipids in the plasma membrane can mice within the bilayer
Most lipids and some proteins drift laterally
Rarely do they flip flop transversely across the membrane

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4
Q

Do proteins move in the membrane?

A

Some drift within the bilayer
Move slower than lipids
Some moved by motor proteins in the cytoskeleton
Some never move and are anchored by The cytoskeleton

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5
Q

Cholesterol regulates the ___________ of a membrane

A

Fluidity

Cholesterol wedges between plasma membrane of animal cells

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6
Q

Two types of membrane proteins

A

Peripheral proteins- loosely bound, cytoplasmic side and exterior side
Integral proteins- within the membrane

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7
Q

Proteins that have a hydrophobic and hydrophilic regions, transmembrane proteins

A

Integral proteins

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8
Q

Covalent attachments of a lipid to an amino acid side chain within a protein

A

Lipid-anchored proteins

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9
Q

Six major functions of membrane proteins??

A
  • transport
  • enzymatic activity (speed up chemical reactions)
  • signal transduction
  • Cell-cell recognition
  • intercellular joining
  • attachment to the cytoskeleton and extracellular matrix (ECM)
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10
Q

Cells recognize each other by binding to surface molecules, often ___________, on the plasma membrane

A

Carbohydrates

Also glycolipids, glycoproteins, usually branched oligosaccharides with fewer than 15 sugar units

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11
Q

The asymmetrical distribution of proteins, lipids and associated carbohydrates in the plasma membrane is determined when the membrane is built by the _________________

A

ER and Golgi apparatus

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12
Q

What can pass through the plasma membrane rapidly, dissolve in the lipid bilayer?

A

Hydrophobic (nonpolar) molecules and gasses

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13
Q

What does not pass through the plasma membrane easily? Mostly transported through transport proteins

A

Hydrophilic/ polar molecules

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14
Q

What diffuses slowly across the PM?

A

Ions

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15
Q

Water enters through the plasma membrane though….

A

Aquaporins

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16
Q

What allows the passage of hydrophilic substances or certain ions across the membrane?

A

Transport proteins

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17
Q
  • bind to molecules and change shape to shuttle them across the membrane
  • specific for the substances it moves
  • how sugar is brought in
A

Carrier proteins

18
Q

Does facilitated transport require energy?

A

No

19
Q

With diffusion each substance diffuse ________ their concentration gradient

A

Down

20
Q

Water diffuses across a membrane from a region of ________ solute concentration to region of ________ solute concentration

A

Lower, higher

21
Q

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

A

Tonicity

22
Q

When cells with walls are in a hypotonic they become….

A

Turgid(from) this is normal for plants

23
Q

When plants are in a isotonic solution they are…..

A

Flaccid (limp)- the plant may wilt

24
Q

When a plant cell is in a hypertonic solution what happens?

A

Plasmolysis - membrane pulls away from the wall, usually lethal

25
Q

What kind of transport always goes from high to low concentrations

A

Passive

Facilitated transport is passive but needs proteins

26
Q

Corridors that allow a specific molecule or ion to cross the membrane (some are gated)

Energy is not required, molecules follow their concentration gradient

A

Channel proteins type of facilitated diffusion

27
Q

Undergo a subtle change in shape that translocates the solute-binding site across the membrane

Energy is not required, molecules follow their concentration gradient

A

Carrier proteins type of facilitated diffusion

28
Q

Sodium-potassium pumps create what type of gradient?

A

Electrochemical

29
Q

With sodium-potassium pumps, _____ K+ goes ______ the cell and _____NA+ goes _____the cell

Inside the cell the charge is _________
Outside the cell the charge is _______

A

2, into
3, out

Negative, positive

30
Q

What is membrane potential

A

The voltage difference across a membrane

31
Q

What is the main electrogenic pump of plants, fungi, and bacteria?

A

Proton pump

32
Q

Transport protein that generates the voltage across the membrane

A

Electrogenic pump

33
Q

What is the difference between primary and secondary active transport?

A

Primary directly uses energy to transport solute, secondary uses pre-existing gradient to drive transport of solute

34
Q

Occurs when active transport of a solute indirectly drives transport of another solute
Ex: plants commonly use the gradient of hydrogen ions generated by proton pumps to drive active transport of nutrients into the cell

A

Cotransport: coupled transport

Uniport
Symptoport (both of the same direction)
Antiport (go in opposite directions)

35
Q

Large molecules, such as polysaccharides and proteins, cross the membrane via _______

A

Vesicles

36
Q
  • transport vesicles migrate to the membrane, fuse with it, and release their contents
  • many secretory cells use this to export their products
  • energy is required
A

Exocytosis

37
Q

Liquids or solids are taken up by the cell by invagination of the plasma membrane
Requires energy

A

Endocytosis

38
Q

“Cellular eating”

Cell engulfs particles in a vacuole

A

Phagocytosis

Type of endocytosis

39
Q

Cellular drinking

Cell creates vesicle around fluid

A

Pinocytosis

Type of endocytosis

40
Q

Binding of ligands to receptors triggers vesicle formation ex: cholesterol

A

Receptor-mediated endocytosis