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Biosci 107 - Cell Processes > Lecture 21 > Flashcards

Lecture 21 Flashcards

1
Q

Selective permeability of membrane

A
  • The molecular organization of the membrane selects what can go in or out of the cell
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2
Q

What is permeable across the cell membrane

A
  • Non polar, uncharged molecules(O2, N2, benzene)
  • Lipid soluble molecules (steroids, fatty acids, some vitamins)
  • Small uncharged polar molecules( water, urea, glycerol, Co2)
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3
Q

What is impermeable across the cell membrane

A
  • Large uncharged polar molecules( glucose, amino acids, ions)
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4
Q

Diffusion meaning

A
  • Net movement of random mixing of particles kinetic energy from high concentration to low concentration.
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5
Q

What is diffusion driven by?

A
  • A concentration gradient
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6
Q

Greater difference in concentration between 2 sides of the CM the rate of diffusion would be

A
  • Faster
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7
Q

High temperature causes a fast or slow rate of diffusion

A
  • A faster rate of diffusion across CM
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8
Q

Larger molecules & increasing diffusion distance through the CM causes a slow or fast rate of diffusion?

A
  • Slower rate of diffusion
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9
Q

What are the physical consequences of diffusion

A
  • Increase diffusion
  • Sets a limit to the size of the cell( 20um thick)
  • membrane thickness
  • Very fast over small distances
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10
Q

Alternative name for cell membrane

A
  • Two-dimensional fluid
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11
Q

What are the main constituents of the CM

A
  • Phospholipids & proteins
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12
Q

Lipid bilayer structure

A
  • Polar head groups that are hydrophilic

- Non-polar fatty acid tails that are hydrophobic

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13
Q

Amphipathic means

A
  • Each molecule of the phospholipid bilayer have both polar & non-polar region
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14
Q

What does the cell membrane allow by controlling the passage of substances into & out of the cell?

A
  • Concentration gradients are maintained
  • Organization of chemical and physical processes in the cell
  • Controlled up-take of nutrients & discharge of water products & secretion of molecules
  • Develops a membrane potential
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15
Q

Membrane fluidity meaning

A
  • The free movement of protein & lipid constituents within the CM
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16
Q

Fluidity is determined by

A
  • lipid tail lengths

E.g: Longer tail > Less fluidity > less permeable

17
Q

Two basic classes of membrane proteins

A
  • Integral Membrane proteins

- Peripheral Proteins

18
Q

Integral membrane proteins structure

A
  • Extend or completely across the cell membrane (transmembrane protein)
  • They are amphipathic
  • Hydrophilic ends of the proteins interact with the aq solution
19
Q

Peripheral proteins structure

A
  • attached to either the inner or outer surface of the cell membrane
20
Q

Membrane proteins can act as (RCLECT)

A
  • Receptors
  • Cell identity Markers
  • Linkers
  • Enzymes
  • Channels ions
  • Transporters proteins
21
Q

What percent does the cell use of resting energy to maintain concentration and electrical gradients

A
  • 30% of resting energy
22
Q

The movement of a non-polar molecule will diffuse across down or against its concentration gradient

A
  • Down it’s concentration gradient
23
Q

Electrical gradient meaning

A
  • a gradient of electrochemical potential for an ion that can move across a membrane
24
Q

How can cells maintain a difference in charged ions between the inside & outside of the membrane

A
  • Electrical gradient or membrane potential
25
Q

Osmosis

A
  • The diffusion of water across membrane form high to low concentration of water
26
Q

What is the concentration of solution on the side of the membrane with high concentration of water?

A
  • Low solute concentration ( Dilute solution)
27
Q

Osmolarity meaning

A
  • The concentration of a solution expressed as the total number of solute particles per liter
28
Q

Same osmolarity is

A
  • Isosmotic
29
Q

Lower osmolarity

A
  • Hyposmotic
30
Q

Higher osmolarity

A
  • Hyperosmotic
31
Q

Concentration of body fluids is

A
  • 280mOsmol
32
Q

Tonicity

A
  • The effect of a solution has on cell volume.
33
Q

Isotonic solution

A
  • No change in cell volume
34
Q

Hypotonic solution

A
  • Cell swelling & eventually cell lysis(haemolysis)
35
Q

Hypertonic Solution

A
  • Cell shrinkage(crenation)

Biosci 107 - Cell Processes (2 decks)

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