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BMSC 207 > Module 2 > Flashcards

Module 2 Flashcards

1
Q

What are the functions of a cell membrane?

A
  • act as a physical barrier separating the intracellular and extracellular fluid, and separating the cell from the environment.
  • controls entry, elimination, and release of molecules and substances.
  • contains proteins that allow for responding or interacting with the external environment.
  • provides structural support.
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2
Q

What is the cell membrane composed of?

A

Lipids, proteins, and a small amount of carbohydrates.

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3
Q

What are the three types of lipids found in the cell membrane?

A

Phospholipids, sphingolipids, and cholesterol.

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4
Q

What are integral proteins? What are their roles?

A

Integral proteins include transmembrane proteins and lipid anchored proteins.
They have roles as: membrane receptors, cell adhesion molecules, channels, carriers, pores, pumps, enzymes, and mediators of intracellular signalling.

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5
Q

What are peripheral proteins? What are their roles?

A

Peripheral proteins attach to integral proteins and are loosely attached to the phospholipid head.
Their roles include: participating in intracellular signalling and forming the submembraneous cytoskeleton.

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6
Q

What are lipid anchored proteins commonly associated with?

A

Commonly associated with sphingolipids instead of phospholipids.

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7
Q

What are lipid rafts? What are they abundant in?

A

Lipid rafts help to form the structure of cells. They are abundant in proteins important for cell signal transduction.

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8
Q

What is a glycoprotein? What does it do?

A

A glycoprotein is a protein with carbohydrate attached.

It forms a protective coat, and acts as a structural, transport, or immunologic molecule, and a hormone.

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9
Q

What is a glycolipid? What does it do?

A

A glycolipid is a lipid with a carbohydrate attached.

It serves as a recognition site for cell to cell interactions.

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10
Q

Where is cholesterol located in the cell membrane? What does it do?

A

Cholesterol is positioned between phospholipid heads to add flexibility and help make the membrane impermeable to small water-soluble molecules.

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11
Q

What are the concentrations of Na+, K+, Cl-, HCO3-, and proteins in the intracellular fluid?

A

Low concentrations of Na+, Cl-, and HCO3- (less than 20mmol/L)
High concentrations of K+ and proteins (more than 100mmol/L)

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12
Q

What are the concentrations of Na+, K+, Cl-, and HCO3- in the interstitial fluid?

A

Low concentrations of K+ and HCO3- (less than 30mmol/L)

High concentrations of Na+ and Cl- (more than 100mmol/L)

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13
Q

What are the concentrations of Na+, K+, Cl-, HCO3-, and proteins in the plasma?

A

Low concentrations of K+ and HCO3- (less than 20mmol/L)

High concentrations of Na+, Cl-. and proteins (more than 70mmol/L)

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14
Q

What is osmolarity? How does it differ from molarity?

A

Osmolarity describes the number of particles in solution.
Differs from molarity in the sense that it focuses on osmotically active individual particles as opposed to entire molecules.

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15
Q

What does it mean when a solution is isosmotic?

A

The solutions have identical osmolarities.

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16
Q

What does it mean when a solution is hyperosmotic?

A

It describes the solution with the higher osmolarity.

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17
Q

What does it mean when a solution is hyposmotic?

A

It describes the solution with the lower osmolarity.

18
Q

What is tonicity?

A

Tonicity describes a solution and how that solution would affect cell volume if a cell were placed in the solution and allowed to come to equilibrium.

19
Q

What is the difference between tonicity and osmolarity?

A

Tonicity depends on the concentration of non-penetrating solutes, whereas osmolarity depends on both penetrating and non-penetrating solutes.

20
Q

What is diffusion?

A

The movement of molecules from an area of higher concentration to an area of lower concentration.

21
Q

What does the rate of diffusion across a membrane depend on to be faster?

A

The rate of diffusion is faster if:

  • the membrane’s surface area is larger
  • the membrane is thinner
  • the concentration gradient is larger
  • the membrane is more permeable to the molecule
22
Q

What does a membrane’s permeability to a molecule depend on?

A
  • the molecule’s lipid solubility
  • the molecule’s size
  • the lipid composition of the membrane
23
Q

What are channel proteins made of? What do they create?

A

Made of membrane spanning protein subunits that create a cluster of cylinders with a pore through the centre

24
Q

What are carrier proteins? What do they do?

A

Carrier proteins are large complex proteins that change conformation to move molecules that cannot pass through channels. (slow process)

25
Q

What is facilitated diffusion? In what direction does it move? is energy required?

A

Diffusion that uses channels or carrier proteins.
Molecules move down their concentration gradient.
No energy is required.

26
Q

What is active transport? Does it require energy?

A

Transport that moves molecules against their concentration gradients: from an area of low concentration to an area of high concentration.
It requires energy.

27
Q

What is primary active transport? How many Na+ move out? How many K+ move in?

A

Transport where the energy used to move the molecule comes directly from hydrolyzing ATP (ATPase).
3 Na+ out, 2 K+ in

28
Q

What is secondary active transport? In what direction can it move?

A

Transport that uses the potential energy stored in the concentration gradient of one molecule to push another molecule against their concentration gradient.
Can move in the same direction (symport) or in the opposite direction (antiport).

29
Q

What does specificity refer to?

A

The ability of a transporter to move one molecule or a closely related group of molecules.

30
Q

What is meant by competition when referring to movement of molecules?

A

A carrier may move several members of a related group of substances but these substances compete with one another.

31
Q

What is meant by saturation?

A

The rate of transport depends on the concentration and the number of transporters.
Transport normally increases with increasing concentration until the transport maximum is reached.

32
Q

What is vesicular transport?

A

Macromolecules that cannot fit through a carrier or channel use phagocytosis, endocytosis, or exocytosis with vesicles created from the cell membrane.

33
Q

What is phagocytosis? Does it require energy?

A

Phagocytosis creates vesicles using the cytoskeleton. It requires ATP.

34
Q

What is endocytosis? Does it require energy?

A

Endocytosis is transport into a cell. It indents the membrane and the vesicles are much smaller than in phagocytosis.
Requires ATP.

35
Q

What is exocytosis? Does it require energy?

A

Exocytosis is transport out of a cell. It can occur continuously or intermittently when initiated by some sort of signal.
Requires ATP and can be regulated by Ca^2+

36
Q

What is transcellular transport?

A

Transport across epithelial cells. Requires energy.

37
Q

What is paracellular transport?

A

Transport between tight junctions. Does not require energy.

38
Q

What is transcytosis?

A

Transport of larger substances. Requires energy.

39
Q

What is membrane potential?

A

The electrical disequilibrium that exists between the extracellular fluid and the intracellular fluid.

40
Q

What is an electrochemical gradient?

A

The combination of electrical and concentration gradients.

41
Q

What is the equilibrium potential?

A

The membrane potential that exactly opposes the concentration gradient in any given concentration gradient of a single ion.

42
Q

What two factors influence a cell’s membrane potential?

A

The concentration gradients of different ions across the membrane and the permeability of the membrane to those ions.

BMSC 207 (6 decks)

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