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Physio Fall 22 > L5 Membranes > Flashcards

L5 Membranes Flashcards

1
Q

What are the five macromolecules that make up the plasma membrane and describe their function

A

Carbohydrates - cell identity

Proteins - transport

Cholesterol - fluidity

Phospholipids - form selectively permeable barrior

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2
Q

What are the functions of the plasma membrane

A

Transport - protein channels, pumps, carriers

Communication - protein receptors

Metabolism - protein enzymes

Structure - cytoskeleton proteins ( create cell junction)

Self identify markers - proteins that protect ( prevents autoimmunity)

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3
Q

Concentration gradient

A

Drives molecules down/ with concentration

(Passive process)

High ➡️ low

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4
Q

What is a passive process? Active?

A

Passive process = no energy required

Active = requires energy (ATP)

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5
Q

What are the 2 membrane transports?

A

Driving force and ATP

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6
Q

————— powers protein pumps ( driving molecule up concentration)

A

ATP

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7
Q

What 2 things effect a molecules pathway through a membrane?

A
  1. Molecule size
    - small molecules =pass
    - large molecules = not pass w/o transporter (pore, channel)
  2. Molecule polarity
    - Nonpolar = pass
    - polar = transporter
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8
Q

Simple diffusion

A

Random movement of molecules

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9
Q

Net diffusion

A

Directional movement of molecules ( driven by concentration gradient)

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10
Q

Channel- mediated facilitated diffusion

A
  • “facilitated” by proteins that form channels/ pores

Each channel has specificity
Ex. Ion channels

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11
Q

What are the 4 types of ion channels.

A
  1. Always open
  2. Voltage gated - switch in membrane charge
  3. Ligand gated - need neurotransmitter to open
  4. Mechanically gated - gated ion channels
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12
Q

Carrier- mediated facilitated diffusion

A

Molecules cross plasma membrane by protein carriers

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13
Q

Mechanism for : Carrier- mediated facilitated diffusion

A
  1. Molecule blinds w/ specificity to protein carriers (glucose, amino acids)
  2. Binding = shape change of carrier protein ➡️ molecule transported and released
  3. Released molecule = shape change back to original shape of protein carrier
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14
Q

What mechanism of water is used when cells need to move lots of water quickly?

A

Aquaporins - channel specifically for water

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15
Q

Primary active transport (pumps)

A

Uses ATP to phosphorylate transport protein

3 types : Na+/K+ pump , ca+ pump & protein pump

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16
Q

List the steps of the mechanism for Na+ / k+ pump

A
  1. 3 Sodium bind w/ specificity
  2. Activation of ATPase site
  3. Pump is phosphorocated
  4. Protein changes shape & sodium ions released
  5. Potassium binds
  6. Phosphate is released (@ ATPase site)
  7. Shape change back to original shape & potassium ions released
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17
Q

Secondary active transport and 2 sub parts

A

Energy is stored in Na+ concentration gradient ➡️ moving Na+ into cell &

Co-transport = same direction (down concentration)

Counter- transport = opposite direction (up concentration)

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18
Q

Osmosis

A

Net diffusion of water through a selectively permeable membrane

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19
Q

What molecules will promote osmosis and what will NOT promote osmosis?

A

Will = o2, co2, cholesterol

Not = h2o, Na+, glucose (c6H12O6)

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20
Q

What is Tonicity?

A

Comparison of solute concentration between 2 solutions

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21
Q

Hypertonic

A

One solution has more active solute than other

22
Q

Hypotonic

A

A solution has less active solute than other solution

23
Q

Isotonic

A

Active solute is the same on both sides

24
Q

Osmolarity means

A

Measure of concentration of osmotically active solutes

25
Q

What are osmotically active solutes?

A

Solutes that don’t easily cross the plasma membrane

26
Q

What is the set point for the parameter osmolarity?

A

300 mOsm

27
Q

What does cremation mean?

A

To shrink

28
Q

What does lysis mean?

A

To burst (the cell membrane)

29
Q

Epithelial transport

A

Transport across sheets of epithelial cells (membranes)

30
Q

What three transport mechanisms are required for epithelial transport?

A
  • Na+/ K+ pump
  • secondary (active) transport
  • carrier mediated facilitated diffusion (passive)
31
Q

What is the purpose of bulk transport?

A

It allows large molecules to cross the membrane

32
Q

What does intercellular signaling mean?

A

Happens b/w cells where one cell releases a messenger molecule and it binds to a receptor on another cell

33
Q

Define ligand

A

Anything that binds to a protein with specificity

34
Q

Endocytosis vs exocytosis

A

Endocytosis = captures substrate/ particle from outside and brings it into cell

Exocytosis = out of cell ; release contents out of the cell

35
Q

What are the three types of Endocytosis and how are they different?

A

Phagocytosis- “to eat” - engulfs small part

Pinocytosis - “pinch close - closes lightly

Receptor- mediated endocytosis- ligand binding to receptor

36
Q

Where can receptors be located in the cell?

A

The cytoplasm ( cytosol)
Plasma membrane
Nucleus

37
Q

Define signal transduction

A

Events between activation of receptor (binding of ligand ➡️ receptor) and the response by the cell

38
Q

Define Autocrine ( intercellular signaling)

A

Communication that acts on its self

39
Q

Paracrine (intercellular signaling)

A

Acts on neighboring cell

40
Q

Endocrine (intercellular signaling)

A

Released by endocrine gland into blood

41
Q

Synaptic signaling (intercellular signaling)

A

Released by neuron ➡️ synapse ➡️ acts on adjacent nerve/muscle/gland

42
Q

Neuroendocrine (intercellular signaling)

A

Released by neuron into blood ➡️ acts on target cell

43
Q

Receptor location is based on ———

A

Polarity (solubility) of ligand

44
Q

What happens after messanger molecule binds to receptor?

A

Signal concentration converts ligand binding event ➡️ intercellular signal altering behavior of cell

45
Q

What is membrane potential

A

Measure of charge difference (mv) across membrane

46
Q

What is resting membrane potential (RMP) in humans?

A

-70mv

47
Q

What causes the -70mv RMP?

A
  • Na+/k+ pump (3 Na+ out & 2 k+ in)
  • more k+ leak channels than Na+ channels
  • large negatively charged proteins
48
Q

What is the value of Na+ equilibrium?

A

60mv

49
Q

What is the value for K+ equilibrium potential?

A

-90mv

50
Q

Is k+ or Na+ responsible for the generation of the RMP? Why?

A

K+ is responsible for RMP due to :

  • having more k+ leak channels than Na+ leak channels
  • RMP closer to k+ equilibrium potential
  • membrane is more permeable to k+ than Na+
51
Q

Explain 3 important functions that the Na+/k+ pump plays in cells

A
  1. Creates/ maintains ion gradients (RMP)
  2. Creates Na+ gradient for secondary active transport
  3. Prevents osmotic damage

Physio Fall 22 (24 decks)

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