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bio & history > bio-membrane transport > Flashcards

bio-membrane transport Flashcards

0
Q

“fluid mosaic” model

A

Lumpy, constantly changing / shifting mosaic of “tiles” (proteins)

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1
Q

Functions of the plasma membranes

A

Isolates cells contents from environment
Regulates exchange of essential substances
Communicate with other cells
Creates attachments within and between other cells
Regulates biochemical reactions

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2
Q

Structure of cell membranes

A

Phospholipid bilayer with proteins scattered throughout

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3
Q

Describe phospholipid bilayer

A

2 rows of phospholipids, hydrophilic heads facing outwards on both sides, hydrophobic tails facing inwards in between

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4
Q

What drives the phospholipids to form a bilayer

A

The exterior and interior of the membrane face watery environments (extracellular fluid, cytosol), hydrophilic heads must face outwards in both sides with tails between

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5
Q

Purpose of cholesterol in membranes on animal cells

A

Keeps it flexible

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6
Q

What holds the phospholipids together

A

Weak interactions between phospholipids NOT BONDED TOGETHER

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7
Q

What happens if the fatty acid tails of the phospholipids are unsaturated? Saturated?

A

If it’s unsaturated there are kinks in their tails, if Saturated they are more straight

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8
Q

What makes the membrane fluid?

A

Individual phospholipids aren’t bound together,

Unsaturated fatty acids make membrane more fluid than if they were saturated

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9
Q

Where are proteins found in the membrane

A

Embedded within phospholipid bilayer (either floating or anchored in)

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10
Q

Glycoproteins

A

Proteins with attached carbohydrates

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11
Q

Categories of membrane proteins

A 
Receptor proteins 
Recognition proteins
Enzymatic proteins
Attachment proteins 
Transport proteins
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12
Q

Receptor proteins

A

Trigger cellular responses upon binding specific molecules (look at pics in ppt)

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13
Q

Recognition proteins

A

Serve as identification tags on the surface of the cell

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14
Q

Enzymes

A

Promote chemical reactions that either make or break up biomolecules

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15
Q

Attachment proteins

A

Anchor the cell membrane to the inner cytoskeleton, to proteins outside the cell, and to other cells

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16
Q

Transport proteins

A

Regulate import/export of hydrophilic molecules

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17
Q

Types of transport proteins

A

Channel and carrier proteins

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18
Q

Homeostasis

A

Maintain a stable internal state

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19
Q

Biggest contributor in maintaining homeostasis in a cell

A

Cell membrane

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20
Q

What does it mean to reach equilibrium

A

All molecules are equally spread out

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21
Q

Opposite of equilibrium

A

Gradient

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22
Q

Fluid

A

A substance that can move or change shape in response to external forces

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23
Q

Solute

A

A substance that can be dissolved (dispersed as ions or molecules)in a solvent

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24
Q

Solution

A

A mixture in which one substance is dissolved evenly in another

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25
Q

Solvent

A

Fluid capable of dissolving a solute

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26
Q

Concentration

A

How much solute in a given amount of solvent

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27
Q

Gradient

A

A physical difference in temperature, pressure, charge, or concentration in 2 adjacent regions

28
Q

Why do molecules move from one place to another

A

In response to a concentration gradient

29
Q

Concentration gradient

A

A difference between concentrations in a space

30
Q

Diffusion

A

When molecules spread from an area of high concentration to an area of low concentration until equilibrium is reached

31
Q

The greater the concentration gradient…

A

…the faster the rate of diffusion

32
Q

Diffusion cannot…

A

…move molecules rapidly over long distances

33
Q

Supersaturated solution

A

Dissolves as much as it can, excess comes out

Ex: coffee with too much sugar, sugar settles at bottom

34
Q

2 types of transport across plasma membrane

A

Passive transport

Active transport

35
Q

Passive transport :
Which direction do molecules move (in terms of concentration gradient)?
Is energy is expended?

A

Molecules move down concentration gradient
**membrane proteins and phospholipids may limit what can cross, but not direction of movement
No energy expended

36
Q

Active transport :
Which direction do molecules move (in terms of concentration gradient)?
Is energy is expended?

A

Molecules move against concentration gradient

Energy is expended

37
Q

Selectively permeable

A

Membranes that allows some things through but not all, like the cell membrane

38
Q

Types of passive transport

A

Simple diffusion
Facilitated diffusion
Osmosis

39
Q

Simple diffusion

A

Lipid soluble molecules and very small molecules directly diffuse across the phospholipid bilayer

40
Q

Facilitated diffusion

A

Water soluble molecules diffuse across the bilayer with the aid of channel and carrier (carrier changes shape) transport proteins (look at pics in ppt)

41
Q

Osmosis

A

Diffusion of water

42
Q

Types of solutions

A

Isotonic
Hypotonic
Hypertonic

43
Q

What makes water less pure

A

More dissolved substances because -> Less free water molecules

44
Q

Isotonic solutions

A

No net flow of water (equal amount flowing in and out)

When both sides of the membrane have an equal amount of water and dissolved substances

45
Q

Hypertonic solution

A

Low water concentration/high dissolved particle concentration
More Water moves TOWARDS hypertonic solution (than the amount that’s going opposite direction)

46
Q

Hypotonic solution

A

Higher concentration of water/lower concentration of dissolved particles
More Water moves AWAY from hypotonic solution (than going in opposite direction)

47
Q

Red blood cell in isotonic solution

A

Equal water going in and out of cell

48
Q

Red blood cell in hypertonic solution (ex: ocean water)

A

Red flood cell will shrivel up

net water movement is out of cell

49
Q

Red blood cell in hypotonic solution

A

Cell will fill up and eventually burst

Net water movement is into the cell

50
Q

Explain the contractile vacuole in freshwater Protists

A

Cytosol in protist is hypertonic to freshwater so water flows into protist, but contractile vacuole is pumped with salt, and becomes hypertonic to the cytosol, so water flows into the contractile vacuole where it is contracted out

Freshwater–> cytosol–> vacuole–> out to freshwater

51
Q

Types of energy-requiring transport

A

Active transport
Endocytosis
Exocytosis

52
Q

Why is active transport necessary

A

To stockpile things – must move against concentration gradient

53
Q

Active transport

A

Uses Membrane proteins called pumps that have a molecule binding site and an ATP binding site
Molecule and ATP bind–> energy from ATP changes shape of transport protein –> molecule is moved across membrane (against concentration gradient)–> protein closes / goes back to original shape and used ATP is released as ADP and P

54
Q

Purpose of endocytosis

A

To import large molecules or substances

55
Q

Types of endocytosis

A

Pinocytosis
Receptor-mediated endocytosis
Phagocytosis

56
Q

Pinocytosis (“cell drinking”)

A

A dimple forms in plasma membrane –> it deepens and fills with extracellular fluid–> membrane closes off the dimple, forming a vesicles filled with extracellular fluid

57
Q

Receptor-mediated endocytosis

A

Only moves specific molecules into the cell
Receptor proteins for specific particles on coated pit sites–> receptors bind the particles and membrane dimples inward–> coated pit región encloses the receptors forming a “coated vesicle” that is released into cytosol

58
Q

Phagocytosis (“cell eating”)

A

Moves large particles or even whole organisms into cell
Cell membrane extends pseudopods toward the particle–> ends of pseudopods fuse together, encircling the particle, and forming a vesicles called a “food vacuole”

59
Q

Exocytosis

A

Vesicle fuses with the cell membrane and dumps its contents out

60
Q

Problem with large cells

A

The organelles get further away from plasma membrane

There isn’t enough surface are of cell membrane to satisfy the needs of the large cell

61
Q

Types of specialized junctions

A

Desmosomes
Tight junctions
Gap junctions/plasmodesmata

62
Q

Desmosomes

A

Has protein strands that Attach cells together

Found where cells need to adhere tightly together under stresses of movement (ex: skin)

63
Q

Tight junctions

A

Formed by strands of proteins
Make cell leakproof
Found where tubes and sacs must hold contents without leaking (ex: urinary bladder)

64
Q

Gap junctions

A

Allow for communication
cell-to-cell channels allowing for passage of hormones, nutrients, and ions
Only in animals

65
Q

Plasmodesmata

A

Allows for communication
Cytoplasmic connections with same function as gap junctions
Only in plants

66
Q

How are plasma membranes adapted for caribous (who live in cold temperatures)?

A

Cell membranes near their hooves are made of more phospholipids with unsaturated fatty acid tails because unsaturated fats can stay liquid at cold temperatures, allowing the membrane to stay fluid

67
Q

What does the plasma membrane have to do with snake and spider venoms?

A

The venoms have an enzyme that breaks down phospholipids, so the venoms attack cell membranes and destroy them, causing the cells and tissue to die

bio & history (20 decks)

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