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Physiology Concepts 1: Cell Membranes Flashcards

1
Q

Name the 3 lipid components of the cell membranes?

A

Phospholipids, cholesterol, sphingolipids

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2
Q

What are the functions of cell membrane?

A

1.)Molecular partitioning and homeostasis
2.) Transport
3.) Movement
4.) Cellular integrity
5.) Cellular signaling

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3
Q

What are the 3 components of a glycerophospholipid?

A

1.) Fatty acid tail
2.) Glycerol backbone
3.) Phosphate “head”

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4
Q

How many carbons are there usually in the fatty acid tail of a glycerophospholipid?

Is it usually an even or odd number?

A

16-18

Even

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5
Q

Is the fatty acid tail of a glycerophospholipid usually branched or unbranched? Saturated or unsaturated?

A

Unbranched

May be saturated or unsaturated

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6
Q

In a GPL, what type of linkage connects the glycerol backbone to the FA tails?

A

Ester linkage

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7
Q

What is the most common steroid in the body?

A

Cholesterol

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8
Q

Cholesterol intercalates between ________ with the -OH closest to the ___________ interface.

A

Cholesterol intercalates between PHOSPHOLIPIDS with the -OH closest to the AQUEOUS interface.

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9
Q

The amount of cholesterol impacts membrane ______________.

A

Fluidity

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10
Q

Why do larger amounts of cholesterol increase fluidity?

A

The cholesterol interferes with the interactions between lipid tails.

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11
Q

A sphingolipid consists of what in place of glycerol?

A

Sphingosine

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12
Q

True or false. A slightly different shape can decrease membrane fluidity.

A

True.

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13
Q

Often sphingolipids have ____________ residues that can serve a number of functions.

A

Sugar residues

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14
Q

STUDY CELL MEMBRANE STRUCTURE

A

Slide 4

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15
Q

STUDY GLYCOSPHINGOLIPID STRUCTURES

A

Slide 8

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16
Q

Define amphipathic

A

Having both hydrophobic and hydrophilic parts

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17
Q

True or false. Lipids in the cell membrane are hydrophobic.

A

False. They are amphipathic

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18
Q

Due to there amphipathic nature, lipids in the cell membrane can form what 2 structures?

A

1.) Phospholipid bilayer
2.) Micelle

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19
Q

The integrity of the _____________ membrane is key to the survival and normal function of the cell.

A

The integrity of the plasma membrane is key to the survival and normal function of the cell.

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19
Q

As the concentration of phospholipids increase, which formation is more favourable? Micelle or bilayer?

A

Bilayer

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20
Q

3 functions of the plasma membrane.

A

1.) Ionic and fluid homeostasis
2.) Keeps vital molecules needed for cellular metabolism within the cell
3.) Cellular movement and shape due to interaction between the cell membrane and the cytoskeleton

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21
Q

What do the membranes INSIDE the cell NOT need to do? (x3)

Do they have a need for spingolipids?

A

1.) Signal to other cells
2.) Protect cells from harsh environments or microbes
3.) For a glycocalyx

No

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22
Q

Is there more or less cholesterol in the membranes of organelles?

A

Much LESS

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23
Q

STUDY IMAGE OF CELL

A

Slide 13

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24
Which intracellular membrane-bound components might have more cholesterol and/or sphingolipids? Why?
25
What are the 4 functions of membrane proteins?
1.) Signaling
26
What are the 2 key forces at work across the cell membrane?
Diffusion and osmosis
27
What is diffusion?
The movement of molecules from a region of HIGHER to LOWER concentration
28
What is thermodynamics?
The spreading of molecules (energy) as they collide against each other.
29
What is osmosis?
Diffusion of water through a semi-permeable membrane
30
True or false. The exterior of the cell has a higher concentration of large solutes than the interior.
False. The INTERIOR of the cell has a higher concentration of large solutes than the EXTERIOR.
31
What is an aquaporin?
AKA water channel. Facilitates transport of water between cells.
32
Do plasma membranes expend energy to regulate solute concentration and cell volume?
Yes
32
How many Na+ are transported OUT of the cytosol, into the extracellular fluid?
3 Na+
32
How many K+ are transported INTO the cytosol, out of the ECF?
2
33
The hydrolysis of __________ is involved in the Na+/K+ pump?
ATP --> ADP + Pi
34
What enzyme is used in the Na+/K+ pump?
ATPase
35
Which 3 solutes have higher concentration in the ECF?
Na+, Cl-, Ca+2
36
Which 2 solutes have higher concentrations in the ICF/cytosol?
K+ and protien
37
ATPase pump is needed to pump Na+ Cl- and Ca+2 (IN or OUT) of the cell and protein and K+ (IN or OUT) of the cell?
ATPase pump is needed to pump Na+ Cl- and Ca+2 OUT of the cell and protein and K+ IN of the cell?
38
Why is the Na+/K+ ATPase pump important?
To prevent cellular swelling
39
Since Na+ in the ECF is high, there is a _________ force that drives it into the cell. (This force can be used to transport other substances into or out of the cell.
Diffusional
40
What kind of transport? A protein moves a substance(s) across a membrane against a concentration gradients using ATP
Active transport
41
What kind of transport? A protein forms a channel that allows a substance across the membrane, along its concentration gradient.
Passive transport
42
A protein carrier binds to a substance and transports it across a membrane, allowing it to follow its concentration gradient
Facilitated transport
43
What kind of transport? The transport of 2 substances (X and Y) are coupled using the same protein. The concentration gradient of X favours movement into the cell - Y is "pulled" along, even if the gradient for Y does not favour cell entry.
Co-transport
44
What kind of transport? X and Y move in opposite directions across the cell membrane - the gradient of one of the molecules supplies the energy to drive the transport.
Counter transport
45
___________ or ___________ are required for passive transport unless the molecule is small and hydrophobic (i.e. carbon dioxide, oxygen)
Channels or transporters
46
Energy is required for which kind of transport?
Active
47
Where does the energy come from for active transport? (2 possibilities)
1.) Energy from hydrolysis of ATP 2.) Energy from the gradient of another molecule **Both require an integral membrane protein
48
What kind of extracellular signals do cells respond to? (2)
1.)Growth factors and "anti-growth" signals 2.) Signals that change cellular activity (Hormones, neurotransmitters)
49
True or false. Most signals involve the binding of a chemical (the signal) to a high-affinity protein receptor on the cell membrane.
True
50
Most cell receptors have what 3 things?
1.) Hydrophobic domains that extend through the lipid bilayer (usually an alpha helix) 2.) An extracellular domain that binds to the message (i.e hormone) 3.) An intracellular domain that amplifies the signal
51
What are the 4 functions of the membrane proteins?
1.) Signaling 2.) Transport & general homeostasis 3.) Protection 4.) Structure & movement
52
Membrane proteins that link the cell to extracellular structures (ECM, other cells) are known as __________.
Junctions
53
Tight junctions separate cells into ________ and ________ compartments.
apical and basal
54
True or false. Tight junctions can be very selective and "leak-proof", or be less selective.
True.
55
What is the purpose of tight junctions?
To regulate movement across membranes and other epithelial structures.
56
What is the intracellular component of a desmesome?
A plaque formed of molecules that are associated with CADHERINS (transmembrane glycoprotein).
57
What are intermediate filaments made of?
Keratin
58
In the extracellular component of a desmosome, ___________ on one cell interact with __________ on a neighboring cell.
Cadherins / cadherins
59
What type of junction is a demosome?
Anchoring junction
60
What is the purpose of a desmosome?
Structure
61
What protein is involved in a hemidesmosome?
Integrin
62
Where does a hemidesmosome bind to?
The integrin binds to the basement membrane.
63
What is the function of a hemidesmosome?
Helps epithelial cells stay anchored to the basement membrane and underlying connective tissue.
64
What 2 places can an adheren junction connect to?
1.) Another cell - cadherin 2.) A basement membrane - integrinse
65
What type of junction is a hemidesmosome?
Anchoring junction
66
What type of junction is an adherin junction?
Anchoring junction
67
What do adherens connect with instead of intermediate filaments?
Microfilaments formed from actin
68
What are the 4 functions of the cytoskeleton?
1.) Cellular movement 2.) Organization of cellular components/organelles 3.) Cellular structure 4.) Communication
69
Which structure is responsible for: 1.) Trafficking of organelles and cell division 2.) Organization of overall cellular structure 3.) Cellular movement
Microtubles
70
Which cellular structure is responsible for: 1.) Cellular movement 2.) Structural organization of the plasma membrane
Microfilaments
71
Which molecules are in microtubles?
Tubulin
72
Which molecules are in microfilaments?
Actin
73
What is the function of the intermediate filaments?
1.) Overall structural integrity of the cell
74
What molecules are in intermediate filaments?
Keratins Desmin
75
In the cytoskeleton, _______________ are constantly "building themselves" into their polymer strands.
Filament subunits (monomers, heterodimers)
76
What is formed when monomers reach a critical concentration and interact with nucleating factors?
Polymers
77
Is the cytoskeleton tightly regulated?
Yes. Filament assembly and disassembly is regulated by a huge array of intracellular signals.
78
Actin monomer is _________.
G-actin
79
Actin polymer is ___________.
F-actin
80
Each G- actin has an ________ bound.
ATP
81
Over time, the G-actin hydrolyzes ATP to ADP, which makes in more likely that it will "fall off" what strand?
The F-actin strand
82
Which nucleating factor or inhibitory factor modifies the formation of F-actin?
Foramin
83
In which type of cell are actin filaments "long-lasting", very precisely organized, and strongly anchored to the cell membrane and other proteins?
Muscle cell
84
What structure needs to "crawl" to an area in order to deposit collagen/ECM?
Fibroblast
85
True or false. Microtubules are more complicated than actin.
True
86
What is the protein monomer in microtubules?
Tubulin
87
What 2 types of dimers organize themselves in a helical tube in microtubules?
Alpha and beta
88
What do beta monomers hydrolyze?
A nucleotide triphosphate
89
What happens to the dimer after GTP is cleaved?
It tends to fall off then fall apart (dynamic instability)
90
MTOC is composed of two centrioles that for the ____________.
Centrosome
91
What is the unique shape that the centrioles have?
Tubulin triplet structure (9 tubulin triplets known as the "9x3" structure.)
92
What helps determine polarity of the cell?
Cellular scaffolding
93
Microtubules are important for what 3 cellular functions?
1.) Cellular movement 2.) Cell division 3.) Signaling
94
________ and________ are formed from microtubules. These structures rotate and move in a whip-like fashion.
Flagella - sperm cells Cilia - respiratory mucosa
95
During __________, the MTOC splits and pulls chromosomes to new daughter cells using newly-generated microtubules.
Cell division
96
What function does the primary cilium have?
Signaling
97
________ is a protein that can "walk" and advance along microfilaments.
Myosin
98
What happens in a muscle when the myosin moves along an actin scaffold.
The entire cell contracts.
99
Which 2 proteins are responsible for moving along microtubules and causing "whipping" movements of cilia and flagella.
Dyneins and kinesins
100
Dyneins and kinesins move ___________ along microtubules a.) In the same direction b.) In opposite directions
b.) In opposite directions
101
What form of energy do the molecular motors use to move along the cytoskeleton, by dragging the structure along?
ATP
102
What type of filament is much more diverse than actin and tubulin?
Intermediate filaments
103
Intermediate filaments are encoded by how many different genes?
70
104
Intermediate filament structures are:
Monomer-->dimer-->tetramer---->8 tetramers
105
What type of filament is the network of filaments just under the nuclear membrane?
Lamins
106
What type of filament are epithelial cells, hair, and nails made of? Its strong and modified to limit water permeability.
Keratins
107
Which intermediate filament is found in the neurons?
Neurofilaments
108
What type of filaments are responsible for the shape of the microvili?
Actin
109
What is organized to provide strength across the cell?
Desmin
110
True or False. Microtubules have a "+" and "-" end
True.

Physiology (11 decks)

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