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Biology Of The Cell > Week 4: Membranes > Flashcards

Week 4: Membranes Flashcards

1
Q

What is the primary function of cell membranes?

A

To keep the inside in and the outside out

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2
Q

What surrounds the nucleus and mitochondria in eukaryotic cells?

A

A double membrane

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3
Q

What is the structure of the plasma membrane?

A

A lipid bilayer made of lipids and proteins

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4
Q

What are the two main components of biological membranes?

A
  • Lipids
  • Proteins
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5
Q

What is the role of cholesterol in the lipid bilayer?

A

Provides structural support

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6
Q

Define amphipathic molecules.

A

Molecules that are hydrophilic (water loving) and hydrophobic (water hating)

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7
Q

What do lipid bilayers spontaneously form in aqueous environments?

A
  • Micelles
  • Bilayers
  • Spherical structures
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8
Q

What is the typical behavior of lipids in membranes?

A
  • Fluidity
  • Lateral diffusion
  • Rotation
  • Flexion
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9
Q

True or False: Flip-flopping of lipids in the membrane is common.

A

False

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10
Q

What are membrane proteins responsible for?

A
  • Transport
  • Structural links
  • Receptors
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11
Q

How many proteins are there approximately per 50 lipids in a membrane?

A

1 protein

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12
Q

What type of protein can only be separated from the membrane with detergents?

A

Integral membrane proteins

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13
Q

Fill in the blank: The carbohydrate layer on the cell surface is called the _______.

A

glycocalyx

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14
Q

What is the purpose of the glycocalyx?

A

Involved in cell adhesion and protection

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15
Q

What types of molecules are typically transported across membranes?

A
  • Small water-soluble molecules
  • Ions
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16
Q

What do carrier proteins do?

A

Bind solutes and initiate a conformational change to transport them

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17
Q

How do channel proteins function?

A

Contain a pore through the membrane that is controlled for opening

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18
Q

What is the permeability of the lipid bilayer to hydrophilic molecules?

A

Barrier to most hydrophilic molecules

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19
Q

What types of molecules are mostly excluded by the lipid bilayer?

A
  • Uncharged polar molecules
  • Ions
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20
Q

What is the difference between integral and peripheral membrane proteins?

A
  • Integral proteins: separated with detergents
  • Peripheral proteins: separated with changes in pH or salt
21
Q

What is the role of membrane proteins in cellular signaling?

A

They allow inside things to get out and outside things to get in

22
Q

What type of protein is involved in membrane curvature in the ER?

A

Reticulons

23
Q

What type of anchor do GPI-linked proteins have?

A

Glycosylphosphatidylinositol (GPI) anchor

24
Q

What are the examples of membrane proteins that are involved in signal transduction?

A
  • EGFR (epidermal growth factor receptor)
  • Heterotrimeric G-proteins
25
Q

What is the purpose of maintaining different solute concentrations inside and outside the cell?

A

To protect the cell and maintain the chemistry in organelles

26
Q

Fill in the blank: Membranes act as a selective _______.

A

barrier

27
Q

What initiates a conformational change in the protein during solute transport?

A

Solute binds on one side of the membrane

28
Q

What is released on the other side after solute binding?

A

Solute

29
Q

Give an example of a transporter that binds solute.

A

Glucose transporters (GLUTs)

30
Q

How do channel proteins differ from transporters?

A

Channel proteins do not bind the solute but contain a ‘pore’ through the membrane

31
Q

What type of transport moves molecules from high to low concentrations?

A

Passive transport

32
Q

What type of transport moves molecules ‘uphill’?

A

Active transport

33
Q

What do carrier proteins do in passive transport?

A

Bind molecules on the high concentration side and move them to the low concentration side

34
Q

What influences the passive movement of charged ions?

A

Electrical and chemical gradient

35
Q

What is a coupled carrier?

A

The transport of one molecule is ‘coupled’ with another

36
Q

What is an example of a symport coupled carrier?

A

Na-glucose carrier

37
Q

What do ATP-driven pumps use to drive active transport?

A

Hydrolysis of ATP

38
Q

What is an example of an ATP-driven pump?

A

Na+-K+ pump

39
Q

What is the function of the Na+-K+ pump?

A

Needed for muscle function and to maintain charge potential across the membrane

40
Q

What do ion channels facilitate?

A

Passive transport of ions through hydrophilic pores

41
Q

How many molecules can ion channels allow to pass per second?

A

10^8 molecules

42
Q

What influences the opening/closing of ion channels?

A

Gating mechanisms

43
Q

What is the selectivity of ion channels based on?

A

Narrow pore allowing contact between the ion and the pore wall

44
Q

What types of cells are voltage-gated ion channels especially useful for?

A

Nerve cells (neurones) and skeletal muscle cells

45
Q

What conditions can malfunctioning ion channels cause?

A

Epilepsy and neuromuscular conditions

46
Q

What are the main components of cell membranes?

A
  • Lipid bilayer
  • Membrane proteins
  • Sugar coat
47
Q

Fill in the blank: The lipid bilayer is a _______ barrier.

A

selective

48
Q

Name two ways small molecules cross the membrane barrier.

A
  • Carrier proteins (passive or active transport)
  • Channel proteins (ion channels - passive transport only)

Biology Of The Cell (23 decks)

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