Biological Membranes Flashcards

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1
Q

Cell Plasma Membrane

A

Semi-permeable phospholipid bilayer selectivity is mediated by channels and carriers (Water soluble). The membrane permits fat soluble compounds through

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2
Q

Proteins & Signaling Areas in the Membrane

A

Embedded in the bilayer to act as cell receptors during signal transduction and maintain overall cellular activity

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3
Q

Phospholipids

A

Move rapidly in the plane of the membrane through simple diffusion

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4
Q

Lipid Rafts

A
  • Primary component of cell membranes that provide structure
  • Phosphate group serves as the attachment point for other water soluble biomolecules
  • Secondary messenger in signal transduction
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5
Q

Membrane Components

A
(Most plentiful)
- Lipids
- Proteins
- Carbohydrates
- Nucleic Acids
(Least plentiful)
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6
Q

Unsaturated Fatty Acids

A

Impart fluidity to the membrane

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7
Q

Glycerophospholipids

A

Used for membrane synthesis

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8
Q

Cholesterol

A
  • Imparts fluidity to the membrane
  • Synthesizes steroids
  • Provides stability by linking adjacent phospholipids and occupying the space between them
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9
Q

Waxes

A
  • Serve an extracellular function in protection and waterproofing
  • Provide stability / rigidity within the nonpolar tail region of the membrane
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10
Q

Transmembrane Proteins

A

Pass completely through the lipid bilayer

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11
Q

Embedded Proteins

A

Interior (cytoplasmic) OR Exterior (Extracellular) proteins on the surface of a cell

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12
Q

Peripheral Proteins

A

They are transporters, channels and receptors bound with the lipid bilayer, lipid rafts or other transmembrane and embedded proteins

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13
Q

Carbohydrates

A
  • Hydrophilic
  • Attached at extracellular side
  • Function in signaling and molecule recognition
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14
Q

Receptors

A

(De)Activate transporters for facilitated diffusion or active transport

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15
Q

Cell Adhesion Molecules (CAMs)

A

Cell-Cell junctions that allow cells to recognize each other and contribute to proper cell differentiation and development

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16
Q

Gap Junctions

A
  • Direct Cell-Cell communication

- Connexons permits water / solutes movement

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17
Q

Tight Junctions

A

Prevent solutes from leaking into intracellular space via a paracellular route. They create a physical link between cells to form a waterproof seal

18
Q

Desmosomes

A

Bind adjacent cells by anchoring to their cytoskeleton

19
Q

Hemi-Desmosomes

A

Attach epithelial cells to underlying (basement membranes)

20
Q

Simple Diffusion

A
  • Passively move from a High [ ] Gradient —> Low [ ] Gradient until equilibrium is achieved
  • Does not require a transporter
  • Substrates move directly across membrane

Ex: Small, nonpolar molecules like O2 and CO2

21
Q

Osmosis

A
  • Moves from Low [ ] Gradient —> High [ ] Gradient
  • Diffusion across a selectively permeable membrane
  • Move H2O Only
22
Q

Hypotonic Solution

A

Lower concentration of solution outside the cell, [Solutes] increase in the cell, Resulting in a net flow of water into the cell (cell will swell, increase in size)

23
Q

Hypertonic Solution

A

Higher concentration of solution outside of the cell, [Solutes] decrease in the cell, Resulting in a net flow of water out of the cell (cell will shrink, decrease in size)

24
Q

Isotonic Solution

A

Equimolar [Solutes] inside and outside of the cell, resulting in no net flow of water

25
Q

Osmotic Pressure Equation

A

Osmotic Pressure - iMRT

i = Van't Hoff Factor (# of molecules that a compound dissociates into)
M = Molarity of solution
R = Ideal gas constant
T = Temperature
26
Q

Facilitated Diffusion

A
  • Moves from High [ ] gradient —-> Low [ ] gradient
  • Transport proteins facilitate movement
  • Carriers will open 1 side of the membrane at a time
  • Channels are exposed to both sides of the membrane when open
27
Q

Passive Transport

A
  • Positive Entropy (S) - increases
  • Negative Free Energy (G) - Spontaneous
  • Does not require energy
28
Q

Active Transport

A
  • Positive Free Energy (G) - Nonspontaneous

- Moves [ ] against the gradient

29
Q

Primary Active Transport

A
  • Uses ATP Hydrolysis (or another energy molecule) to directly transport molecules across the membrane.
  • May involve Transmembrane ATPase
30
Q

Secondary Active Transport

A
  • One molecule moves down the [ ] gradient which releases energy to move a different molecule up it’s [ ] gradient
31
Q

Endocytosis

A

Cell membrane invaginates and engulfs material to bring into cell

32
Q

Pinocytosis

A

Fluids and dissolved particles are engulfed by the cell membrane and brought into the cell

33
Q

Phagocytosis

A

Large solids and bacteria are engulfed by the cell membrane

34
Q

Exocytosis

A

Secretory vesicles fuse with the membrane, releasing materials from the inside of the cell into the extracellular environment

35
Q

Na+ and K+ Pump

A
  • 3 Na+ out and 2 K+ in
  • Leak channels (more K+) allows ions to permeate through the cell membrane
  • Both maintain a stable resting membrane potential
36
Q

Outer Membrane Mitochondria

A
  • Highly permeable

- large pores move ions and small proteins

37
Q

Inner Membrane Mitochondria

A
  • Contain Cristae (foldings)
  • Restricted Permeability
  • Encloses matrix
38
Q

Osmotic Pressure

A
  • Colligative Property

- Pressure applies to a pure solvent to prevent osmosis, and is related to the [ ] of the solution

39
Q

Symport (Active Transport)

A

Transport mechanism that moves two compounds simultaneously across a cell membrane in the same direction, one compound being transported down a concentration gradient and the other against a gradient

40
Q

Antiport (Active Transport)

A

Cell membrane transport mechanism that transports two molecules at once through the membrane in opposite directions.

41
Q

Countertransport (Active Transport)

A

Simultaneous transport of two substances across a membrane in opposite directions, either by the same carrier or by different carriers that are biochemically linked to each other.