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MBOC > Membraan architectuur 1 > Flashcards

Membraan architectuur 1 Flashcards

1
Q

Discuss the structural components of phospholipids, focusing on the structure of phosphatidylcholine. Why is there a diverse range of membrane lipids, and how does this diversity impact membrane functions?

A

Phospholipids have a phosphate head, glycerol backbone, and two fatty acid tails. Diversity in lipid structure arises from variations in head groups, backbones, and fatty acid chains. This diversity contributes to the adaptability and specificity of membrane functions.

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2
Q

What are the reasons for incorporating drugs into liposomes for medical applications?
a. To increase drug inactivation in the blood
b. To enhance drug toxicity
c. To prevent controlled release
d. To inhibit targeting possibilities

A

b. To enhance drug toxicity

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3
Q

How are liposome vesicles initially formed in the process of drug encapsulation?
a. By chemical synthesis
b. Through passive diffusion
c. By spontaneous lipid bilayer formation
d. Via active transport

A

c. By spontaneous lipid bilayer formation

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4
Q

What is the role of cholesterol in membrane organization?
a. Decrease membrane stability
b. Increase membrane fluidity
c. Enhance lateral movements of proteins
d. Modulate membrane fluidity and stability

A

d. Modulate membrane fluidity and stability

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5
Q

Describe the regulation of lipid composition in response to changes in environmental temperature. Provide an example of an organism that adjusts its lipid composition and the impact on membrane fluidity.

A

Organisms like E. coli adjust lipid composition in response to temperature changes. At higher temperatures, they increase saturated fatty acids, reducing membrane fluidity, while at lower temperatures, more unsaturated fatty acids increase fluidity.

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6
Q

Explain the concept of membrane fluidity and how it is influenced by factors such as temperature, lipid chain length, and saturation. Why is membrane fluidity crucial for cellular processes?

A

Membrane fluidity refers to the flexibility of lipid molecules. It is influenced by temperature, longer unsaturated chains increase fluidity, and shorter saturated chains decrease it. Proper fluidity is crucial for membrane protein function, lateral movement, and dynamic cellular processes.

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7
Q

Which method is NOT mentioned as a way to remove drugs located outside liposomes after encapsulation?
a. Gel permeation chromatography
b. Dialysis
c. Centrifugation
d. Filtration through a 200 nm filter

A

d. Filtration through a 200 nm filter

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8
Q

What is the primary driving force for the self-assembly of membrane structures?
a. Hydrophilic interactions
b. Hydrogen bonding
c. Hydrophobic effect
d. Ionic bonding

A

c. Hydrophobic effect

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9
Q

What is the primary problem associated with multi-drug resistance (MDR) in the context of chemotherapy?
a. Rapid drug inactivation
b. Poor liposome stability
c. Overexpression of P-glycoproteins (Pgp)
d. Inability to encapsulate hydrophobic drugs

A

c. Overexpression of P-glycoproteins (Pgp)

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10
Q

Why is tumor tissue considered more permeable for drug delivery using liposomes?
a. Higher expression of P-glycoproteins
b. Presence of fewer receptors
c. Lower pH in tumor tissue
d. Similar lipid composition to normal tissue

A

c. Lower pH in tumor tissue

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11
Q

Discuss the role of membrane fluidity in the functionality of membrane proteins. How does membrane fluidity impact the lateral movements of proteins in the membrane?

A

Proper membrane fluidity is essential for the flexibility and function of membrane proteins. Fluidity influences lateral movements, affecting protein interactions, signaling, and the ability of proteins to undergo conformational changes.

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12
Q

Why are membranes essential for the proper functioning of cells? List the 5 key functions that membranes must fulfill.

A

Membranes are essential for cellular integrity and function. Key functions include:
- Providing a non-leaky barrier.
- Selectively allowing the passage of substances.
- Transmitting signals.
- Facilitating energy supply and storage.
- Allowing dynamic processes like fusion.

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13
Q

What is a potential advantage of using liposomes for drug delivery in terms of drug inactivation?
a. Faster inactivation in the blood
b. Protection against rapid inactivation
c. Enhanced toxicity
d. Targeted drug inactivation

A

b. Protection against rapid inactivation

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14
Q

What is the role of amphipathic molecules in membrane formation?
a. To increase membrane rigidity
b. To promote membrane leakage
c. To facilitate hydrophilic interactions
d. To shield hydrophobic regions from water

A

d. To shield hydrophobic regions from water

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15
Q

What role does cholesterol play in membrane organization? How does cholesterol-rich domain formation (rafts) affect membrane properties and functions?

A

Cholesterol modulates membrane fluidity and stability. Cholesterol-rich domains, such as rafts, impact membrane properties by influencing lateral distribution, protein interactions, and cellular processes.

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16
Q

Describe the importance of lipid-protein interactions in membrane structure and function. How are lipids and proteins complementary in the context of cellular membranes?

A

Lipid-protein interactions are crucial for maintaining membrane integrity and facilitating protein function. Proteins and lipids are complementary, with proteins often having hydrophobic regions interacting with lipid tails and hydrophilic regions interacting with lipid head groups.

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17
Q

Explain the concept of lipid melting and the factors that influence the transition from a gel phase to a liquid phase. How does the length and saturation of fatty acid chains affect the melting temperature of lipids?

A

Lipid melting is the transition from a gel to a liquid phase. Longer and saturated fatty acid chains increase the melting temperature, making the membrane more rigid, while shorter and unsaturated chains lower the melting temperature, increasing fluidity.

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18
Q

Which factor does NOT influence membrane fluidity?
a. Temperature
b. Lipid chain length
c. Protein concentration
d. Lipid saturation

A

c. Protein concentration

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19
Q

What is a characteristic feature of liposome drug delivery to tumor tissue?
a. Increased drug inactivation
b. Lower pH in the bloodstream
c. Targeting through overexpressed receptors
d. Similar lipid composition to normal tissue

A

c. Targeting through overexpressed receptors

20
Q

What are the characteristics of model membranes, and why are they used in research? Provide examples of studies that involve model membranes.

A

Model membranes mimic biological membranes. They are used to study lipid structures, interactions, and functions. Studies include investigating drug carriers using liposomes and understanding the impact of membrane composition on the action of anesthetics.

21
Q

What is the impact of longer and saturated fatty acid chains on lipid melting temperature?
a. Decrease melting temperature
b. Increase melting temperature
c. No effect on melting temperature
d. Convert gel phase to liquid phase

A

b. Increase melting temperature

22
Q

Discuss the importance of lipid composition in membrane organization. How do lipids with different structures contribute to membrane properties?

A

Lipid composition influences membrane fluidity, thickness, and organization. Lipids with different structures impact the membrane’s ability to form bilayers, affecting permeability, stability, and interactions with proteins.

23
Q

What are non-bilayer lipids, and how do they contribute to membrane organization? Provide examples of non-bilayer lipids and their functions in cellular membranes.

A

Non-bilayer lipids, like phosphatidylethanolamine (PE), contribute to highly curved membrane structures. They play roles in membrane fusion, vesicle formation, and altering membrane properties. PE can form hexagonal phases with unique structural characteristics.

24
Q

Why are membranes essential for cell function?
a. To provide structural support
b. To regulate temperature
c. To act as a selective barrier
d. To store genetic information

A

c. To act as a selective barrier

25
Q

How did RNA molecules contribute to evolution, and what functions were eventually taken over by proteins and DNA?

A

RNA molecules had catalytic and genetic functions. Proteins took over catalytic roles, and DNA became the primary carrier of genetic information due to its increased stability and specificity.

26
Q

Describe the evolution of membranes. What is the significance of simple lipid structures like soap bubbles in understanding membrane formation?

A

Membranes evolved from simple structures like soap bubbles. These structures demonstrate self-assembly principles, serving as models for understanding the basic principles of membrane formation through the hydrophobic effect.

27
Q

Explain the hydrophobic effect and its role in the self-assembly of membrane structures. How do amphipathic molecules contribute to membrane formation?

A

The hydrophobic effect is the tendency of hydrophobic (non-polar) molecules to aggregate in water to minimize unfavorable interactions. Amphipathic molecules, with both hydrophilic and hydrophobic regions, spontaneously form membranes by orienting themselves to shield hydrophobic portions from water.

28
Q

Explain the significance of lateral distribution and membrane domains (rafts) in cellular membranes. How do these membrane features influence cellular processes and interactions?

A

Lateral distribution and membrane domains influence protein clustering, signaling, and the formation of specific membrane regions. Rafts, rich in cholesterol and sphingolipids, play roles in protein recruitment and signaling, impacting various cellular processes.

29
Q

Which evolutionary function did RNA molecules perform before proteins and DNA took over their roles?
a. Catalytic and genetic functions
b. Structural support
c. Energy storage
d. Signal transduction

A

a. Catalytic and genetic functions

30
Q

Why are model membranes used in research?
a. To study soap bubble formation
b. To mimic complex biological membranes
c. To investigate RNA evolution
d. To store genetic information

A

b. To mimic complex biological membranes

31
Q

What is the primary structural component of phospholipids?
a. Glycerol backbone
b. Fatty acid tails
c. Phosphate head
d. Cholesterol

A

a. Glycerol backbone

32
Q

Which component can be chemically coupled to lipids for targeting in liposome drug delivery?
a. Fatty acids
b. Antibodies
c. Water-soluble vitamins
d. Amino acids

A

b. Antibodies

33
Q

How do organisms regulate lipid composition in response to temperature changes?
a. By increasing unsaturated fatty acids at higher temperatures
b. By decreasing unsaturated fatty acids at lower temperatures
c. By increasing saturated fatty acids at higher temperatures
d. By increasing cholesterol content at lower temperatures

A

c. By increasing saturated fatty acids at higher temperatures

34
Q

What is an advantage of endocytosis and fusion over passive diffusion in drug delivery using liposomes?
a. Increased drug inactivation
b. Bypassing the issue of P-glycoproteins
c. Slower drug uptake by cells
d. Reduced targeting possibilities

A

b. Bypassing the issue of P-glycoproteins

35
Q

How can the size and properties of liposomes be tuned for specific drug delivery applications?
a. By using a fixed size for all applications
b. By incorporating only hydrophobic drugs
c. By chemically coupling lipids with polyethylene-glycol (PEG)
d. By avoiding the use of non-bilayer lipids

A

c. By chemically coupling lipids with polyethylene-glycol (PEG)

36
Q

Explain the process of forming liposome vesicles during drug encapsulation.

A

Liposome vesicles are formed by adding lipids in dry form to a vial, followed by the addition of a buffer and shaking. Spontaneous lipid bilayers are formed due to the hydrophobic effect, resulting in multi-lamellar vesicles. These vesicles are then passed through a filter with pores (e.g., 200 nm) under pressure to obtain uni-lamellar vesicles of homogeneous size.

36
Q

True/False:

Tumor tissue has a higher pH compared to normal tissue.

A

False

36
Q

In the context of drug delivery, the ____________ process bypasses the issue of P-glycoproteins.

A

Endocytosis

37
Q

Match the following drug delivery methods with their advantages:
A. Passive Diffusion

B. Endocytosis

C. Fusion

  • Rapid drug inactivation
  • Bypassing P-glycoprotein issue
  • Controlled release
A

A. Passive Diffusion - 3. Controlled release
B. Endocytosis - 2. Bypassing P-glycoprotein issue
C. Fusion - 1. Rapid drug inactivation

37
Q

Discuss the potential challenges and ethical considerations associated with chemically coupling antibodies to lipids for targeting in liposome drug delivery.

A

This is open-ended and requires a thoughtful response based on the understanding of ethical considerations and potential challenges associated with modifying liposomes for drug delivery.

38
Q

Propose a scenario where liposome drug delivery could be particularly advantageous compared to traditional drug delivery methods.

A

This is open-ended, and a scenario could be related to a specific disease or condition where targeted drug delivery, controlled release, or avoidance of drug resistance is crucial.

39
Q

What is the primary role of p-glycoproteins (Pgp) in the membrane concerning drug delivery?
a. Enhance drug toxicity
b. Facilitate passive diffusion
c. Protect against potentially harmful substances
d. Decrease receptor expression in tumor tissue

A

c. Protect against potentially harmful substances

40
Q

Provide three reasons why liposome drug delivery is considered a versatile approach.

A

This is open-ended. Potential answers could include controlled release, targeting capabilities, reduced toxicity, etc.

41
Q

True/False:

Unilamellar vesicles have a heterogeneous size distribution.

A

False

42
Q

Match the characteristics of tumor tissue with their implications for liposome drug delivery:
A. Increased permeability

B. Overexpression of receptors

C. Lower pH

  • Targeting opportunities
  • Enhanced drug inactivation
  • Facilitates liposome uptake
A

A. Increased permeability - 3. Facilitates liposome uptake
B. Overexpression of receptors - 1. Targeting opportunities
C. Lower pH - 2. Enhanced drug inactivation

43
Q

Draw PE, PC and LPC

A

PE = small head, big tails
PC = same size, rectangle
LPC = big head, just one tail

MBOC (9 decks)

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