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Cells to systems > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

what method was use to move fluid and solutes from interstitial fluid into cells

A
  • Diffusion
  • facilitated diffsion
  • active
  • Co-transport
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2
Q

What move the fluid and solutes from blood to interstitial fluid

A

Bulk flow and Starling’ Forces

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3
Q

what are the different structures in the Plasma membrae

A 
v Phospholipid bilayer
v Proteins
- Integral {full or partial) &
surface or peripheral
v Cholesterol
v Carbohydrates linked to
proteins & lipids
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4
Q

What is the fluid mosaic model

A

v Noncovalent assemblies
v Lipids & proteins move
around within the membrane

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5
Q

Are the internal and external layer similar

A

no, they are asymmetric

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6
Q

What are the movements for lipids

A
  1. Lateral diffusion
  2. Rotation
  3. Swing
  4. Flexion
  5. Transverse diffusion (flip flop)
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7
Q

Where are the position of Phospholipids

A
  • Choline (external)
  • Ethanolamine (internal)
  • Serine (internal)
  • Inositol (signalling)
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8
Q

Where are the position of sphingolipids

A

Sphingomyelin (external)
• Glycosphingolipids
• Associate

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9
Q

What is the role of cholesterol

A

determines
fluidity and permeability
• Within membrane

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10
Q

What is the membrane lipid made up of

A
  • Phospholipids
  • sphingolipids
  • cholesterol
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11
Q

How does the membrane lipid tail length affect fluidity

A

Fluidity decrease with length due to increased van der waal interactions

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12
Q

How does the degree of unsaturation of fatty acids affect the membrane fluidity

A

It increases fluidity

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13
Q

How does cholesterol affect membrane fluidity

A

reduce fluidity

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14
Q

How does hydrophobic diffuse

A

Concentration gradient within membrane is greater, Diffuses quickly

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15
Q

How does hydrophilic diffuse

A

Hydrophilic (polar) substances in membrane are sparingly soluble

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16
Q

What are the 4 types of molecules that may permeate through the membrane

A
  1. Non polar molecules
  2. Small uncharged polar molecules
  3. Large polar molecules & ions
  4. Macromolecules
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17
Q

Does Non polar molecules pass through membrane

A

Pass freely e.g. fatty acids, steroid hormones, CO2, & O2 (acts as
non polar - linear)

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18
Q

Does small uncharged polar moleccules pass through the membrane

A

Pass freely but more slowly than non polar molecules e.g. H2O

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19
Q

Does large polar molecules & ions pass through properly

A

Don’t pass freely eg glucose, Na+ K+

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20
Q

Does macromolecules pass through the membrane

A

Don’t pass e.g. Proteins , polysaccharides, nucleic acids

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21
Q

What are some molecules cross the cell membrane in their non-charged form but not in their charged form

A
  • base (eg ammonia =NH3)

- acid (eg formic acid = HCOOH)

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22
Q

What determine whether the substance is charged or not

A

pH

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23
Q

Are the integral membrane protein permanently attached to the membrane?

A

Yes

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24
Q

What are the types of integral membrane protein

A 
1. Span entire membrane
• once or multiple times
• many a helices
• Examples –voltage gated ion channels ,
hormone receptors eg insulin
2. Integral monotopic proteins
• Examples enzymes -monoamine oxidase
• Do not span the entire biological
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25
Q

How does Peripherally associated membrane

proteins attach to integral protein

A

often non-covalently bound

26
Q

What are the functions of membrane protein

A 
• Transport
v Hydrophilic channel
v ATP-pump
• Enzyme functions
v Active site exposed
• Signal transduction
v Receptors for external signals
• Cell recognition
v Molecules recognised by other
cells proteins
• Control adhesion
v between cells and extracellular
matrix
• Cytoskeletal attachment
v Microfilaments
27
Q

How does simple diffusion function

A 
• Down a concentration or electrical gradient
v Through membrane
v Through pores – integral cell membrane
channel eg aquaporin for water
v Through protein channels – selectively
permeable, may be gated, eg ion channels
28
Q

How does facilitated diffusion function

A

• Down a concentration or electrical gradient
v Carrier mediated - need integral membrane
protein
v Transporter is specific for the molecule
v Rate limited by binding and conformational
change in carrier protein; eg glucose, amino
acids

29
Q

How does active transport function

A

• Up a concentration or electrical gradient

v Carrier mediated and energy dependent

30
Q

What are the type of simple diffusion

A

• open or closed
• “gated”.
• Rate of movement is limited by the
rate of diffusion

31
Q

Types of gated ion channels

A 
• voltage-gated, e.g. Na+ or K+
(specific channel for each)
• Chemical or ligand-gated, e.g.
acetylcholine
• mechanically-gated, e.g. sound
waves in inner ear open ion
channels
32
Q

What are the Ion movement via transport protein affected by

A
  1. Concentration gradient

2. Electrical gradient

33
Q

What is the nernst equation

A

Ex= Equilibrium Potential for x (or electromotive
force preventing further diffusion)
• Value is the membrane voltage for ion to be in
equilibrium
• = (61mV/charge) x log10 (internal
concentration/external concentration)

34
Q

What is the nerve cell transmission activated by

A

• Electrical stimulation (action potential)
• Chemical stimulation (neurotransmitter) eg
acetylcholine

35
Q

What is Epilepsy and tinnitus

A

Overly excited nerves
Voltage-gated K channels usually open to regulate
nerve signals
Remain closed in epilepsy and tinnit

36
Q

What is
• Hyperkalemic Periodic Paralysis in horses
(muscle weaknes

A

Genetic defect in voltage-gated Na channels of muscle
cells
Channels remain open
Results in muscle weakness and co

37
Q

Where are the ion channels gated at

A

Some ion channels are gated by
extracellular ligands; some by
intracellular ligands.

38
Q

What are some external ligands

A
  1. Acetylcholine (ACh)
    n
  2. Gamma amino butyric acid
39
Q

What is Gamma amino butyric acid

A 
BA)
 Binding at certain synapses in the
central nervous system
 Admits Cl- ions into the cell
 Inhibits the creation of a nerve
40
Q

What is Acetylcholine (ACh) ion channel

A 
• Ionotropic receptor
 Nicotinic Ach receptor
 Opens Na+ ion channel
 Depolarization
• Metabotropic receptor
 Muscarinic receptor
 Opens K+ ion channel
 Hyperpolari
41
Q

What is Gamma amino butyric acid

A 
BA)
 Binding at certain synapses in the
central nervous system
 Admits Cl- ions into the cell
 Inhibits the creation of a nerve
42
Q

What are the traits of ion channels

A
  1. Traverse the
    membrane
  2. Ion selective
  3. Gated
43
Q

What are the Different mechanisms for

activating the ion gates

A
  1. Voltage-gated
  2. Ligand-gated
  3. Intracellular
    messengers-gated
  4. Mechanically-gated
    • Stretch
    • Sound waves
44
Q

What does pump protein do

A

against
concentration/electrical
gradients

45
Q

What does gate channels do

A

with
concentration/electrical
gradients

46
Q

What are symporters

A

• Na+ ions flow down their concentration gradient
• Glucose co-binds with Na – transported up the
glucose concentration gradient.
(In most cells: glucose also goes down its concentration
gradient and uses a simple uniporter)

47
Q

What are antiporters

A

• Substances are transported in opposite directions
• Electrochemical gradient for Na+ drives H+ or
Ca++ in in the opposite directio

48
Q

What is a uniporter

A

only a single ion is transported at a time

49
Q

what is a example of symporter

A

(Na /amino acids+)

50
Q

What is an example of an antiporter

A

( Na+/ H+ )

51
Q

What are the secondary “active” trnsport

A

symporter and antiporter

52
Q

Simple
diffusion -
membrane

A

H2O
O2
CO2*

53
Q

Simple
diffusion -
pore

A

H2O

aquaporin

54
Q

Where does active transport happen along the epithelial sheet?

A

one side of the cell

55
Q

Where does simple or facilitated diffusion happen along the epithelial sheets?

A

On other side of the active transport side

56
Q

What is the function of pinocytosis

A 
• Large molecules and particles require
specialised processes to cross the
plasma membrane - endocytosis
• Molecules and particles are engulfed into
intra-cytoplasmic vesicles
• Endocytosis requires energy
57
Q

Does endocytosis require energy

A

yes

58
Q

What are the three types of endocytosis

A

1 Non-receptor mediated pinocytosis
2 Receptor mediated
endocytosis
3 Phagocytosis

59
Q

Non-receptor mediated pinocytosis

A 
Continuous nonspecific uptake of
extracellular fluid and small dissolved
molecules
1. Vesicle buds off from plasma
membrane
2. Vesicle transported intact, releasing
contents to exterior by exocytosis or
fuses with a lysosome
3. Membrane components recycled to
the plasma membrane
60
Q

Receptor mediated

endocytosis

A 
vVia clathrin–coated pits in
epithelial and phagocytic
cell membranes
• Pits contain integral
protein receptors for
molecules being
endocytosed
vVia caveolin-coated pits
(Caveolae) in cell
membranes of vascular
endothelial cells and
adipocytes
• Transport of albumin
• Folate receptor
61
Q

Phagocytosis

A 
• Endocytosis of large
particulate matter such as
microorganisms or cell debris
• Receptor-mediated
• Carried out by specialised
phagocytic cells
• Immune-related
1. Microbe recognised by
receptor
2. Phagosome forms
3. Phagosome fuses with
lysosome (phagolysosome)
4. Microbes killed by
proteolytic enzymes,
reactive oxygen species
(ROS) and nitric oxide (NO)

Cells to systems (25 decks)

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