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BIOL 107 > Introduction to Membranes > Flashcards

Introduction to Membranes Flashcards

1
Q

How can phospholipids spontaneously form membranes?

A

Through their amphipathic nature

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2
Q

How is a micelle formed with phospholipids?

A

Forms because single-tailed phospholipids are conical and their amphipathic nature

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3
Q

Describe phospholipid movement within a bilayer.

A

Can move freely laterally and quickly

Flip/Flop movement is rare because the polar head is unstable in a hydrophobic environment

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4
Q

What are some effects of high temperatures on the phospholipid bilayer?

A

Kinetic energy is increased to cause increased flexibility and permeability and creates gaps between phospholipids

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5
Q

What are some adaptations to high heat on phospholipid bilayers?

A

i) increase in hydrocarbon tail length
ii) decrease in C=C to increase saturation
iii) increase in cholesterol to increase hydrophobicity and create a pylon to slow down phospholipids

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6
Q

What are some effects of low temperatures on the phospholipid bilayer?

A

Space between phospholipids decreases to cause decreased flexibility and permeability

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7
Q

What are some adaptations to low heat on phospholipid bilayers?

A

i) increase C=C to decrease saturation to make molecules larger
ii) decrease hydrocarbon tail length to decrease hydrophobicity
iii) add cholesterol to act as a spacer between phospholipids

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8
Q

What are two types of proteins embedded into the membrane bilayer?

A

Integral membrane protein and peripheral membrane protein

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9
Q

What defines a substance that can freely diffuse across a phospholipid bilayer?

A

Permeable

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10
Q

What is impermeable?

A

A substance that cannot cross the hydrophobic core because it’s either too large or charged

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11
Q

What are the rankings of CO2, glucose and ions from most permeable to least permeable?

A

CO2
Glucose
Ions

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12
Q

Why can ions not cross the plasma membrane?

A

They cannot cross because of a hydration shell of H2O that surrounds the ion due to polarity

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13
Q

What is the movement of molecules from a high concentration to a low concentration?

A

Diffusion (Passive Transport)

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14
Q

What type of solution is a cell in when the solute concentration is higher within the cell than in the solution?

A

Hypotonic solution

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15
Q

What are the risks of a cell being in a hypotonic solution?

A

Can cause osmotic lysis

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16
Q

Describe an isotonic solution.

A

In an isotonic solution, the concentration of solute is equal inside and outside of the cell

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17
Q

What type of solution is when the concentration of solute is higher outside of a cell?

A

Hypertonic solution

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18
Q

What are the risks to a cell in a hypertonic solution?

A

Plasmolysis may occur

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19
Q

What is plasmolysis?

A

The cell shrinks as water goes to the outside of the cell

20
Q

What form of transport describes molecules moving down their concentration gradient using channel proteins or carrier proteins?

A

Facilitated diffusion

21
Q

What is a channel protein?

A

Protein that allows transport of specific solutes without changing shape

22
Q

What is a carrier protein?

A

Protein that allows transport of specific solutes by changing shape

23
Q

What type of transport requires energy?

A

Active transport

24
Q

What is the transportation of molecules up their concentration gradient using energy?

A

Active transport

25
Q

What are the three functions of active transport?

A

i) to concentrate nutrients in the cell
ii) to expel wastes
iii) to maintain a voltage/chemical gradient

26
Q

Describe the process of a Sodium/Potassium pump.

A

i) 3 Na+ bind to a pump from within the cell
ii) ATP provides energy for the protein to change shape
iii) 3 Na+ are released extracellularly
iv) 2 K+ bind to the pump from outside the cell
v) ATP provides energy for the protein to change shape
vi) 2 K+ are released intracellularly

27
Q

What is the role of an electrogenic pump?

A

It generates a voltage difference across the membrane

28
Q

What is the electric function of the Na/K pump?

A

To maintain a charge difference across the membrane called membrane potential which gives an electrochemical gradient

29
Q

What is membrane potential?

A

A charge difference across the membrane

30
Q

What is an electrochemical gradient?

A

There is a difference in concentration of a charged molecule across the membrane

31
Q

What is cotransport?

A

The transport of 2 molecules simultaneously

32
Q

How is Na/K pump an example of cotransport?

A

2K+ come into the cell down both electro and chemical gradients and 3Na+ go out of the cell down concentration gradient but against a charge

33
Q

What is an antiporter?

A

The transport of 2 molecules in different directions

34
Q

What is a symport?

A

The transport of 2 molecules in the same direction

35
Q

Describe the Na/Glucose cotransporter.

A

Na+ flows down its gradient into the cell but takes glucose with it into the cell (glucose against concentration gradient)

36
Q

What is coupled transport?

A

The use of one gradient to establish another

37
Q

What are the two types of bulk transport?

A

Endo and exocytosis

38
Q

What describes bulk transport going out of the cell?

A

Exocytosis

39
Q

Describe the process of exocytosis.

A

i) sorted material from Golgi
ii) vesicle forms around material to be exocytosed
iii) vesicle fuses with membrane
iv) secretion of material

40
Q

What is a small membrane-bound compartment that contains cargo in a cell?

A

Vesicle

41
Q

What is endocytosis?

A

Bulk transport going into the cell

42
Q

What is phagocytosis?

A

Bulk transport of non-specific material into the cell

43
Q

Describe the process of endocytosis.

A

i) material comes to the plasma membrane
ii) vesicle forms around the material at membrane
iii) vesicle is transported to the lysosome
iv) lysosome digests the material

44
Q

What is Receptor-Mediated Endocytosis?

A

Endocytosis of a specific ligand

45
Q

What is a ligand?

A

Anything that binds to a receptor

46
Q

What is a receptor?

A

An integral membrane protein that recognizes and binds a specific ligand

47
Q

Describe Receptor-Mediated Endocytosis.

A

i) ligand approaches receptor in a clathrin-coated pit
ii) ligand binds to its specific receptor
iii) a receptor circled vesicle forms carrying ligand
iv) lysosome digests ligand
v) receptors are recycled

BIOL 107 (4 decks)

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