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Biology 3/4 > Cell Membrane > Flashcards

Cell Membrane Flashcards

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1
Q

Fluid Mosaic Model

A

The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components, including phospholipids, cholesterol, various embedded proteins, and carbohydrates that give the membrane a fluid character.

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2
Q

Ampiphatic

A

to have both hydrophilic and hydrophobic parts

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3
Q

Semipermeable

A

Only some substances are able to pass through the membrane whilst others are kept out.

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4
Q

Structure of The phospholipids

A

Hydrophilic Head - Phosphate and Glycerol

Hydrophobic Tails - Saturated and Unsaturated fatty acids

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5
Q

Lipids - Hydrophobic or Hydrophilic?

A

Hydrophobic

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6
Q

Peripheral Proteins

A

Attached to the surface of the membrane

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7
Q

Transmembrane

A

Type of integral protein that goes straight through the membrane (embedded protein)

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8
Q

Glycoproteins and Glycolipids

A
  • Cell identification
  • Intercellular communication
  • Cell membrane transport
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9
Q

Cholesterol

A
  • Maintains fluidity when the temperature is low

- Maintains integrity when the temperature is high

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10
Q

Functions of the Plasma Membrane

A
  • Compartmentalisation
  • Material Transport
  • Cell Recognition and Communication
  • Packaging or Isolation of Substances
  • Site of Chemical Reactions
  • Allows the Cell to Change Shape
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11
Q

How do Lipid soluble substances cross the Plasma Membrane

A

Lipid Soluble substances dissolve straight through the plasma membrane

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12
Q

How do water-soluble substances cross the plasma membrane?

A
  • Substances that are large but not polymers (including ions, charged molecules) like glucose cannot pass through so it passes through a protein carrier.
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13
Q

How do water and urea pass through the plasma membrane?

A

Water and Urea are polar uncharged molecules and are small enough to pass in between the phospholipids.

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14
Q

How do larger substances cross the plasma membrane?

A

Larger substances like polymers pass through the cell membrane via bulk transport (endocytosis and exocytosis)

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15
Q

How do small uncharged molecules pass through the plasma membrane?

A

Small uncharged molecules like oxygen and carbon dioxide are also able to pass through the phospholipid bilayer

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16
Q

What does passive mean?

A

Passive means requiring no energy

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17
Q

What are different types of passive transport?

A
  • Osmosis
  • Simple diffusion
  • Facilitated diffusion
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18
Q

What are different types of Active Transport?

A
  • Active Transport
  • Bulk transport
    • Endocytosis
    • Exocytosis
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19
Q

What is Diffusion?

A

Diffusion is the passive movement of particles from a region of high solute concentration to a region of low solute concentration to achieve equilibrium.

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20
Q

Factors that affect the rate of diffusion

A
  • particle size
  • polarity/solubility
  • charge
  • heat
  • state of matter
  • surface area and to volume ratio
  • concentration gradient
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21
Q

How does particle size affect the rate of diffusion?

A

small molecules such as gasses and water will diffuse through more rapidly than larger molecules

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22
Q

How does polarity affect the rate of diffusion?

A

non-polar substances diffuse directly through the membrane

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23
Q

How does charge affect the rate of diffusion?

A

Neutral substances can pass through the membrane whereas charged molecules cannot

24
Q

How does heat affect the rate of diffusion?

A

Higher temperatures mean that particles have higher levels of kinetic energy causing the particles to move faster increasing the rate of diffusion.

25
Q

How does the state of matter affect the rate of diffusion?

A

gasses diffuse faster than liquids, solids don’t diffuse at all

26
Q

How does the surface area to volume ratio affect the rate of diffusion

A

Increased SA: V ratio means there is a greater surface for reactions/transport to occur

27
Q

How does the concentration gradient affect the rate of diffusion?

A

The larger the gradient the faster the rate of diffusion

28
Q

What are the advantages of diffusion?

A

No energy is required

29
Q

What are the disadvantages of diffusion?

A

Molecules in the cell may be lost due to the concentration gradient.

30
Q

What is osmosis?

A

Osmosis is the passive net movement of water from a region of high water concentration to a region of low water concentration to achieve equilibrium

31
Q

When does osmosis occur?

A

Osmosis occurs when the solute is too large to pass through the semipermeable membrane and only the solvent passes through

32
Q

Hypotonic

A

Used to describe the direction water moves from a region of low solute concentration to a region of high solute concentration.

33
Q

Hypertonic

A

Used to describe the direction water moves from a region of high solute concentration to a region of low solute

34
Q

Isotonic

A

Used to describe the direction water moves in both directions at an equal rate

35
Q

What happens when a cell is placed in a hypotonic solution?

A

When a cell is placed in a hypotonic solution (distilled water) water moves into the cell causing it to swell and sometimes burst.

36
Q

When plant cells are placed in a hypotonic solution what happens?

A

When a plant cell is placed in a hypotonic solution, water moves into the cell and causes it to become turgid but not burst as of the presence of the cell wall which prevents this.

37
Q

What happens when a cell is placed in a hypertonic solution?

A

When a cell is placed in a hypertonic solution (20% NaCl solution) water moves out of the cell causing it to shrivel.

38
Q

What is the term when plant cells shrivel when placed in a hypertonic solution?

A
  • Flaccid
39
Q

What happens when a cell is placed in an isotonic solution?

A

When a cell is placed in an isotonic solution there will be no net movement of water in and out of the cell and the volume will remain the same.

40
Q

What is Facilitated Diffusion?

A

Facilitated diffusion is the passive movement of substances from a region of low solute concentration to a region of high solute concentration with the use of a channel/carrier protein in order to achieve equilibrium.

41
Q

When does facilitated diffusion occur?

A

when charged particles or large soluble molecules like ions and amino acids diffuse across the membrane through protein channels or with the aid of carrier proteins

42
Q

How do substances use carrier proteins?

A

The substance bonds to one end of the carrier protein which then changes shape and releases the substance on the other side of the membrane.

43
Q

Why is facilitated diffusion passive?

A

It is passive because it is still following the concentration gradient which provides the energy for the structural change.

44
Q

What is active transport?

A

Active transport is the movement of particles against the concentration gradient from a region of low solute concentration to a region of high solute concentration with the use of energy

45
Q

When moving substances against the gradient what happens?

A

The movement against the concentration gradient requires energy. The energy is supplied by ATP which is released by breaking a phosphate to produce ADP

46
Q

What is ATP?

A
  • Adenosinetriphosphate
  • ATP–> ADP + Pi + energy
  • Cells that use a lot of active transport require a lot of mitochondria to produce the ATP needed
47
Q

What are some examples of Active Transport?

A
  • The gills of marine fish have cells that can remove the salts from the body by pumping it into the freshwater
  • Plant moves minerals (inorganic ions) into their roots by active transport
  • The thyroid gland cells bring iodine for use in producing hormones
48
Q

What is co-transport?

A

When active transport uses energy to pump materials across the ions or molecules will attempt to move back across the membrane under osmotic pressure. This energy can be used to transport other molecules across the membrane.

49
Q

What are the two different types of Bulk Transport?

A
  • Endocytosis

- Exocytosis

50
Q

What is bulk transport used for?

A

Endocytosis and Exocytosis are used for materials that are too big to pass through the plasma membrane (for example proteins)
- Transport through the formation of vesicles

51
Q

What is Endocytosis?

A

Endocytosis is the process by which a cell engulfs materials to bring them into the cell using energy.

52
Q

What is Pinocytosis?

A

Endocytosis of liquids

53
Q

What is Phagocytosis?

A

Endocytosis of solids

54
Q

What is Exocytosis?

A

Exocytosis is when a vesicle fuses with the plasma membrane and secretes the materials to the outside of the cell requiring energy.
- the fusion of vesicles to the plasma membrane adds membrane to the cells surface

55
Q

Receptor-Mediated Endocytosis

A

Endocytosis but with the use of receptors

Biology 3/4 (3 decks)

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