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Biology 3 > Plasma membrane > Flashcards

Plasma membrane Flashcards

1
Q

What is the plasma membrane?

A

The plasma membrane is the active boundary of a cells.

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2
Q

Describe the structure of the plasma membrane.

A

2D fluid composed of a phospholipid bilayer with embedded proteins.

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3
Q

What force allows phospholipids to move freely?

A

Weak dispersion forces allows the phospholipids to move freely, like a fluid.

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4
Q

Describe structure of phospholipid. (4)

A
  • phosphate head: hydrophilic (polar)

- Fatty acid tail: hydrophobic tail (non polar)

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5
Q

What is the difference between the two hydrophobic tails in a phospholipid?

A

One is saturated (single bonds) and one is unsaturated (double bond present)

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6
Q

What is a glycocalyx?

A

Coating of outer layer of PM with carbohydrate chains.

Gives cell identity by contributing to communication, cell to cell recognition, adhesion and protects from damage.

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7
Q

What are the two types of proteins found in plasma membrane?

A
  • intergral: embedded into membrane, penetrate hydrophobic region
  • peripheral: anchored to exterior, don’t penetrate hydrophobic region
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8
Q

What are the functions of the plasma membrane? (4)

A
  • protective boundary providing selective permeability
  • separates internal contents from external contents of cell
  • glycoproteins allow for cell identity
  • communicates and interacts with external environment and other cells to maintain and balance internal conditions
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9
Q

Want is the function of cholesterol in the plasma membrane?

A

Stabilises the plasma membrane by loosening membrane and reducing movement.
Assists with temp fluctuations.

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10
Q

What are the functions of peripheral proteins? (2)

A
  • cellular communication

- ancor cells

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11
Q

What are the functions of integral proteins? (3)

A
  • transport of materials across PM
  • regulate movement of substance
  • performs functions in and out of the cell
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12
Q

What are the 4 types of proteins found in the plasma membrane?

A
  • receptor
  • recognition
  • transport
  • adhesion
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13
Q

What are lipids responsible for in the plasma membrane? (4)

A
  • flexibility
  • repair
  • shape change
    growth
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14
Q

What factors allow some substances to cross the PM? (4)

A
  • size
  • charge
  • solubility in lipid solvents (polarity)
  • direction of concentration gradient
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15
Q

What is simple diffusion?

A

Movement of a substance from an area of high conc. to an area of low conc.

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16
Q

What are the features of simple diffusion? (3)

A
  • does not require an input of energy
  • moves with conc. gradient
  • crosses directly through the plasma membrane
17
Q

What substances can cross the plasma membrane via simple diffusion?

A

O2(g)

CO2(g)

18
Q

What is osmosis?

A

The passive net movement of water fro an area of high water conc. to an area of low water conc. across a semipermeable membrane.

19
Q

What are the features of osmosis? (3)

A
  • does not require energy
  • moves with conc. gradient
  • often uses aqua porin
20
Q

What 3 terms can describe the comparison between a cell and its external environment?

A
  • hypotonic
  • isotonic
  • isotonic
21
Q

What is a hypotonic solution?

A

When there is a lower conc. of solute outside the cell.

Water will move into cell.

22
Q

What is a hypertonic solution?

A

When there is a higher conc. of solute inside of the cel rather than out.
Water will move out of the cell.

23
Q

What is an isotonic solution?

A

When there is an equal solute conc. in and out of the cell.

24
Q

How does a hypotonic solution affect a plant and animal cell?

A
  • animal: burst

- plant: swell becoming turgid

25
Q

How does a hypertonic solution affect a plant and animal cell?

A
  • animal: shinks

- plant: shrivels away from cell wall

26
Q

What is facilitated diffusion?

A

Passive net movement of a substance from an area of high conc. to an area of low conc. via a protein channel/ carrier.

27
Q

What are the features of facilitated diffusion?

A
  • protein mediated transport
  • does not require energy
  • moves with conc. gradient
28
Q

How do the rates of diffusion of facilitated and simple diffusion compare?

A
  • simple: linear, always room for molecules to move across
  • facilitated: begins fast as there are many channels available, eventually plateaus due to all channels being occupied and no more molecules can be transported until they’re unoccupied
29
Q

What substances can cross the plasma membrane via facilitated diffusion?

A
  • glucose
30
Q

What is active transport?

A

The active net movement of a substance from an area of low conc. to an area of high conc.

31
Q

What are the features of active transport?

A
  • requires an input of energy
  • goes against conc. gradient
  • requires a protein pump
32
Q

What are the types of bulk transport?

A
  • exocytosis
  • endocytosis
  • pinocytosis
  • phagocytosis
  • receptor mediated transport
33
Q

Define exocytosis.

A

Materials exported out of the cell via secretory vessels.

34
Q

Define endocytosis?

A

Materials transported into the cell via three ways.

35
Q

Define pinocystosis.

A

When a fluid is transported in the cell

36
Q

Define phagocytosis.

A

When macromolecules are transported into the cell.

37
Q

Define receptor mediated transport.

A

A trigger has to occur before a receptor will assist the entry of material into a cell.

38
Q

What factors effect permeability?

A
  • temperature: denatures protein or speeds up molecules
  • SA:V: higher SA:V increases rate of dissuasion
  • PH:
  • ethanol: dissolves the lipid components of the membrane.

Biology 3 (10 decks)

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