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Human physiology Spain > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Cell membranes are held together by …. interactions, about … nm thick

A

non-covalent, 5 nm
non-covalent = weak, no sharing of electrons

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2
Q

Lipid bilayer = A %, membrane proteins = B%
Lipid bilayer: provides basic fluid structure. impermeable for C molecules

A

a = 50
b = 50
c = water-soluble

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3
Q

Functions of membrane proteins

A
  1. Transport
  2. Receptor
  3. Catalysis (e.g. ATP synthesis)
  4. Structural (link cytoskeleton to extracellular matrix or
    other cell)
  5. Cellular recognition
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4
Q

Lipid molecules are amphiphilic = ?

A

Hydrophobic non-polar end
* Hydrophilic polar end

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5
Q

Lipid bilayer consists of …. (75%), …. (5%) and …… (20%)

A

phospholipids
glycolipids
cholesterol

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6
Q

What are liposomes?

A

Phospholipid membranes spontaneously
close to form a sealed compartment:
liposomes.
* It is the energetically most favorable
arrangement.

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7
Q

Phospholipid molecules change places with their neighbors in a
monolayer very rapidly (107 times / s): true/false

A

true

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8
Q

Are cholesterol molecules amphiphilic?

A

yes queen they are in the bilayer : heads to heads, tails to tails

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9
Q

glycolipids: where and what do they do

A

Sugar-containing lipid molecules.
* Constitute 5% of total lipid molecules in the
outer monolayer.

Functions:
* Membrane protection
* Cell-recognition
* In nerve cells: membrane electrical propieties.

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10
Q

cell membrane is symmetric with different phospholipid compositions in each of the bilayer leaflets:true/false

A

false

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11
Q

Fluidity of a lipid bilayer depends on….. and ….

A

composition (fatty acid
composition and cholesterol amount)
and temperature

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12
Q

Cholesterol makes the lipid bilayer stronger/weaker but less firm/fluid at normal body
temperature.

A

stronger, less fluid

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13
Q

According to the fluid mosaic model of the membrane structure, membranes are
two-dimensional fluids in which protein are inserted into lipid bilayers.

A

okay

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14
Q

Functions of cell membrane?

A
  1. Diffusion barrier: regulates entry and exit of substances.
  2. Vesicle transport (glandular secretions).
  3. Cell identification: surface proteins allow identifying a cell.
  4. Communication: proteins act as receptors for hormones.
  5. Intercellular connections: cells can be in contact or linked by special
    complexes.
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15
Q

ECF: has more A and B than intracellular fluid

A

A) K+
B) proteins

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16
Q

Given enough time, virtually almost any molecule will diffuse across a proteinfree lipid bilayer down its concentration gradient: molecules move from more to
less concentration (downhill). True/false

A

True, but will take very long

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17
Q

Rate of diffusion across membrane depends on…

A
  • size of molecule
  • polarity (more phobic, more easily)
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18
Q

Lipid bilayers are essentially impermeable to

A

charged molecules (ions).

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19
Q

Passive diffusion: depends on

A

concentration imbalance
Size molecule
Polarity

20
Q

Set the following molecules from fast diffusion - no doffusion through membrane

  1. Large uncharged polar
  2. small uncharged polar
  3. ions
  4. small nonpolar
A
  1. small nonpolar
  2. small uncharged polar
  3. Large uncharged polar
  4. ions
21
Q

Which 3 transport methods across membrane are there? passive or active?

A
  1. simple passive diff (passive)
  2. channels (passive)
  3. transporters (can be active or passive)
22
Q

tonicity: ?

A

Osmolarity of the solution compared to
the plasma osmolarity

23
Q

what types of tonicity are there?

A

isotonic: same in & out
hypotonic: solution lower osm
hypertonic: solution higher osm

24
Q

differences channels and transporters?

A

channels: strictly passive, weaker interactions. faster transport rate,
transp: active or passive, undergo conformational changes

25
Q

ion channels are also highly ….. and ….

A

highly selective
gated (most are close and open in response to stimulus)

26
Q

recall three types of stimuli for ion gate to open

A
  1. voltage
  2. mechanical stress
  3. ligand binding (neurotransm, ion, nucleotide)
27
Q

two gradients control the movement of ions through cell membrane

A
  1. conc gradient
  2. ELECTROCHEMICAL GRADIENT.
28
Q

Typically, the inner surface of the plasma
membrane is more A charged
and the outer surface is more X
charged.

A

A negatively
X positively

29
Q

The combined influence of the concentration gradient and the electrical gradient
on movement of a particular ion is referred to as its x gradient.

A

electrochemical

30
Q

ion channels are responsible for the electrical
excitability of x cells

A

muscle

31
Q

ion channels mediate most forms of electrical signaling in the x system

A

nervous

32
Q

two other words for transporters?

A

carriers/permeases

33
Q

true or false: each transporter only binds and translocates a single solute type

A

true

34
Q

two steps for a transporter to get a molecule across?

A
  1. recognition
  2. conformational change
35
Q

Which 3 states does a transporter have?

A
  1. outward-open
  2. occluded
  3. inward state
36
Q

which 3 types of active transporters are there?

A
  1. uniport (one side to other side)
  2. symport (simultanious transfer in same direction)
  3. antiport (simultanious transfer in opposite direction)
37
Q

endocytosis: passive or active?

A

active

38
Q

What two main pathways for endocytosis are there?

A
  1. Phagocytosis: Large particles
  2. Pinocytosis: molecules and water
39
Q

Phagocytosis:
- requires A through specific membrane receptors (B process)
- It is a(n) passive/active and highly regulated process

A

A recognition
b selective
- active

40
Q

Phagocytosis: Once the phagosome is formed,
it will fuse x
* The content will be digested by
…. enzymes.

A

x lysosomes.
x lysosomal

41
Q

In mammals phagocytosis occurs in specialized cells, such as…

Functions: defense against
pathogens and cleaning cell
debris.

A
  • macrophages
  • monocytes
  • neutrophils
  • dendritic cells
42
Q

Pinocytosis:

is a form of endocytosis involving X
* In pinocytosis, the cell repeatedly takes in X from the surrounding environment
using tiny vesicles.
* Pinocytosis occurs in X cell types

A

X fluids containing small solutes.
X fluid
X many

43
Q

What subtypes of pinocytosis are there?

A
  1. large: macropinocytosis
  2. small (clathrin, caveolin and clathrin + caveolin dependent)
44
Q

Macropinocytosis:

  • A (requires receptor activation).
  • Requires reorganization of the B of the
    cytoskeleton.
  • A protrusion is used like an arm
A

A Selective
B actin filaments

45
Q

Clathrin-dependent:

X coat the vesicle to initiate endocytosis
The vesicle with the cargo
is transported into the cell
and fuses with endosomes
and lysosomes.
X process: ligand-receptor
Requires X

A

X Clathrin protein
X selective
X energy

46
Q

Caveolin-dependent endocytosis

  • Caveolae are small
    X
  • Endocytosis of X and
    X
  • In humans, this process
    occurs in cells lining the
    small intestine and is used
    primarily for absorption.
  • Require much X and the process is
A

X invaginations of the cell’s
plasma membrane.
X fluids and solutes
X energy.
X Nonspecific.

47
Q

In what types of cells is exocytosis especially important?

A
  • secretory cells
  • nerve cells

Human physiology Spain (23 decks)

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