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Physiology > Physiology Concepts 1: Cell Membranes > Flashcards

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
Q

Which intracellular membrane-bound components might have more cholesterol and/or sphingolipids? Why?

A
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25
Q

What are the 4 functions of membrane proteins?

A

1.) Signaling

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26
Q

What are the 2 key forces at work across the cell membrane?

A

Diffusion and osmosis

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27
Q

What is diffusion?

A

The movement of molecules from a region of HIGHER to LOWER concentration

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28
Q

What is thermodynamics?

A

The spreading of molecules (energy) as they collide against each other.

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29
Q

What is osmosis?

A

Diffusion of water through a semi-permeable membrane

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30
Q

True or false. The exterior of the cell has a higher concentration of large solutes than the interior.

A

False. The INTERIOR of the cell has a higher concentration of large solutes than the EXTERIOR.

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31
Q

What is an aquaporin?

A

AKA water channel. Facilitates transport of water between cells.

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32
Q

Do plasma membranes expend energy to regulate solute concentration and cell volume?

A

Yes

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32
Q

How many Na+ are transported OUT of the cytosol, into the extracellular fluid?

A

3 Na+

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32
Q

How many K+ are transported INTO the cytosol, out of the ECF?

A

2

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33
Q

The hydrolysis of __________ is involved in the Na+/K+ pump?

A

ATP –> ADP + Pi

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34
Q

What enzyme is used in the Na+/K+ pump?

A

ATPase

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35
Q

Which 3 solutes have higher concentration in the ECF?

A

Na+, Cl-, Ca+2

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36
Q

Which 2 solutes have higher concentrations in the ICF/cytosol?

A

K+ and protien

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37
Q

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?

A

ATPase pump is needed to pump Na+ Cl- and Ca+2 OUT of the cell and protein and K+ IN of the cell?

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38
Q

Why is the Na+/K+ ATPase pump important?

A

To prevent cellular swelling

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39
Q

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.

A

Diffusional

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40
Q

What kind of transport?
A protein moves a substance(s) across a membrane against a concentration gradients using ATP

A

Active transport

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41
Q

What kind of transport?
A protein forms a channel that allows a substance across the membrane, along its concentration gradient.

A

Passive transport

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42
Q

A protein carrier binds to a substance and transports it across a membrane, allowing it to follow its concentration gradient

A

Facilitated transport

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43
Q

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.

A

Co-transport

44
Q

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.

A

Counter transport

45
Q

___________ or ___________ are required for passive transport unless the molecule is small and hydrophobic (i.e. carbon dioxide, oxygen)

A

Channels or transporters

46
Q

Energy is required for which kind of transport?

A

Active

47
Q

Where does the energy come from for active transport? (2 possibilities)

A

1.) Energy from hydrolysis of ATP
2.) Energy from the gradient of another molecule
**Both require an integral membrane protein

48
Q

What kind of extracellular signals do cells respond to? (2)

A

1.)Growth factors and “anti-growth” signals
2.) Signals that change cellular activity (Hormones, neurotransmitters)

49
Q

True or false.
Most signals involve the binding of a chemical (the signal) to a high-affinity protein receptor on the cell membrane.

A

True

50
Q

Most cell receptors have what 3 things?

A

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
Q

What are the 4 functions of the membrane proteins?

A

1.) Signaling
2.) Transport & general homeostasis
3.) Protection
4.) Structure & movement

52
Q

Membrane proteins that link the cell to extracellular structures (ECM, other cells) are known as __________.

A

Junctions

53
Q

Tight junctions separate cells into ________ and ________ compartments.

A

apical and basal

54
Q

True or false.
Tight junctions can be very selective and “leak-proof”, or be less selective.

A

True.

55
Q

What is the purpose of tight junctions?

A

To regulate movement across membranes and other epithelial structures.

56
Q

What is the intracellular component of a desmesome?

A

A plaque formed of molecules that are associated with CADHERINS (transmembrane glycoprotein).

57
Q

What are intermediate filaments made of?

A

Keratin

58
Q

In the extracellular component of a desmosome, ___________ on one cell interact with __________ on a neighboring cell.

A

Cadherins / cadherins

59
Q

What type of junction is a demosome?

A

Anchoring junction

60
Q

What is the purpose of a desmosome?

A

Structure

61
Q

What protein is involved in a hemidesmosome?

A

Integrin

62
Q

Where does a hemidesmosome bind to?

A

The integrin binds to the basement membrane.

63
Q

What is the function of a hemidesmosome?

A

Helps epithelial cells stay anchored to the basement membrane and underlying connective tissue.

64
Q

What 2 places can an adheren junction connect to?

A

1.) Another cell - cadherin
2.) A basement membrane - integrinse

65
Q

What type of junction is a hemidesmosome?

A

Anchoring junction

66
Q

What type of junction is an adherin junction?

A

Anchoring junction

67
Q

What do adherens connect with instead of intermediate filaments?

A

Microfilaments formed from actin

68
Q

What are the 4 functions of the cytoskeleton?

A

1.) Cellular movement
2.) Organization of cellular components/organelles
3.) Cellular structure
4.) Communication

69
Q

Which structure is responsible for:
1.) Trafficking of organelles and cell division
2.) Organization of overall cellular structure
3.) Cellular movement

A

Microtubles

70
Q

Which cellular structure is responsible for:
1.) Cellular movement
2.) Structural organization of the plasma membrane

A

Microfilaments

71
Q

Which molecules are in microtubles?

A

Tubulin

72
Q

Which molecules are in microfilaments?

A

Actin

73
Q

What is the function of the intermediate filaments?

A

1.) Overall structural integrity of the cell

74
Q

What molecules are in intermediate filaments?

A

Keratins
Desmin

75
Q

In the cytoskeleton, _______________ are constantly “building themselves” into their polymer strands.

A

Filament subunits (monomers, heterodimers)

76
Q

What is formed when monomers reach a critical concentration and interact with nucleating factors?

A

Polymers

77
Q

Is the cytoskeleton tightly regulated?

A

Yes. Filament assembly and disassembly is regulated by a huge array of intracellular signals.

78
Q

Actin monomer is _________.

A

G-actin

79
Q

Actin polymer is ___________.

A

F-actin

80
Q

Each G- actin has an ________ bound.

A

ATP

81
Q

Over time, the G-actin hydrolyzes ATP to ADP, which makes in more likely that it will “fall off” what strand?

A

The F-actin strand

82
Q

Which nucleating factor or inhibitory factor modifies the formation of F-actin?

A

Foramin

83
Q

In which type of cell are actin filaments “long-lasting”, very precisely organized, and strongly anchored to the cell membrane and other proteins?

A

Muscle cell

84
Q

What structure needs to “crawl” to an area in order to deposit collagen/ECM?

A

Fibroblast

85
Q

True or false. Microtubules are more complicated than actin.

A

True

86
Q

What is the protein monomer in microtubules?

A

Tubulin

87
Q

What 2 types of dimers organize themselves in a helical tube in microtubules?

A

Alpha and beta

88
Q

What do beta monomers hydrolyze?

A

A nucleotide triphosphate

89
Q

What happens to the dimer after GTP is cleaved?

A

It tends to fall off then fall apart (dynamic instability)

90
Q

MTOC is composed of two centrioles that for the ____________.

A

Centrosome

91
Q

What is the unique shape that the centrioles have?

A

Tubulin triplet structure (9 tubulin triplets known as the “9x3” structure.)

92
Q

What helps determine polarity of the cell?

A

Cellular scaffolding

93
Q

Microtubules are important for what 3 cellular functions?

A

1.) Cellular movement
2.) Cell division
3.) Signaling

94
Q

________ and________ are formed from microtubules. These structures rotate and move in a whip-like fashion.

A

Flagella - sperm cells
Cilia - respiratory mucosa

95
Q

During __________, the MTOC splits and pulls chromosomes to new daughter cells using newly-generated microtubules.

A

Cell division

96
Q

What function does the primary cilium have?

A

Signaling

97
Q

________ is a protein that can “walk” and advance along microfilaments.

A

Myosin

98
Q

What happens in a muscle when the myosin moves along an actin scaffold.

A

The entire cell contracts.

99
Q

Which 2 proteins are responsible for moving along microtubules and causing “whipping” movements of cilia and flagella.

A

Dyneins and kinesins

100
Q

Dyneins and kinesins move ___________ along microtubules

a.) In the same direction
b.) In opposite directions

A

b.) In opposite directions

101
Q

What form of energy do the molecular motors use to move along the cytoskeleton, by dragging the structure along?

A

ATP

102
Q

What type of filament is much more diverse than actin and tubulin?

A

Intermediate filaments

103
Q

Intermediate filaments are encoded by how many different genes?

A

70

104
Q

Intermediate filament structures are:

A

Monomer–>dimer–>tetramer—->8 tetramers

105
Q

What type of filament is the network of filaments just under the nuclear membrane?

A

Lamins

106
Q

What type of filament are epithelial cells, hair, and nails made of? Its strong and modified to limit water permeability.

A

Keratins

107
Q

Which intermediate filament is found in the neurons?

A

Neurofilaments

108
Q

What type of filaments are responsible for the shape of the microvili?

A

Actin

109
Q

What is organized to provide strength across the cell?

A

Desmin

110
Q

True or False. Microtubules have a “+” and “-“ end

A

True.

Physiology (11 decks)

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