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Biology - TPHS > Cell Membrane (Diffusion, Osmosis, Active Transport etc) > Flashcards

Cell Membrane (Diffusion, Osmosis, Active Transport etc) Flashcards

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1
Q

Are the different substances that make up the cell membrane fixed?

A

No, they are not fixed in place

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2
Q

Describe how the substances within the cell membrane are arranged

A

They are arranged in ‘mosaic’ but are also free to move around within the mosaic.

Therefore, we describe the cell membrane as ‘fluid’

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3
Q

What 4 components make up the cell membrane?

A

Phospholipids

Cholesterol

Proteins

Glycolipids and Glycoproteins

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4
Q

What is the role of the phospholipids in a cell membrane?

A

Form a barrier to dissolved substances

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5
Q

What is the role of the cholesterol in a cell membrane?

A

Gives the membrane stability

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6
Q

What is the role of proteins in a cell membrane?

A

Controls what enters and leaves the cell

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7
Q

What is the role of the glycolipids and glycoproteins in a cell membrane?

A

Act as receptors for messenger molecules (hormones, drugs, antibodies)

For cell signalling

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8
Q

What two kinds of proteins are there?

A

Extrinsic

Intrinsic

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9
Q

Where are extrinsic proteins found in the cell membrane?

A

Found on one surface of the membrane only

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10
Q

Where are the intrinsic proteins found in the cell membrane?

A

They span the entire membrane

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11
Q

What are the functions of proteins in the cell membrane?

A
  1. Act as enzymes (e.g. carbohydrase enzymes are found in the cell membranes of intestinal epithelial cells)
  2. Act as receptors for hormones
  3. Act as carrier proteins, controlling what enters and leaves the cell
  4. Carbohydrates and lipids attached to proteins (forming glycolipids and glycoproteins) allow cells to recognise one another
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12
Q

How to substances leave and enter the cell membrane?

A

Either by diffusion, osmosis or active transport

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13
Q

Meaning of hydrophilic

A

Likes water

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14
Q

Meaning of hydrophobic

A

Dislikes water

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15
Q

Define diffusion

A

The movement of particles from an area of high concentration to an area of low concentration.

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16
Q

Define osmosis

A

The diffusion of water particles across a semi-permeable membrane from an area of high water concentration to an area of low water concentration

17
Q

Passive transport

A

No energy needed. E.g. osmosis, diffusion

18
Q

Active transport

A

Where dissolved molecules more across a cell membrane from an area of low concentration to an area of high concentration

Requires energy as it goes against the concentration gradient

19
Q

Isotonic meaning

A

Concentration is the same both inside and outside of the cell

20
Q

Hypertonic meaning

A

Concentration of dissolves particles are higher outside the cell that inside.

Water will LEAVE the cell.

21
Q

Hypotonic meaning

A

Concentration of dissolved particles are lower outside the cell than inside.

Water will enter the cell.

22
Q

4 Functions of cell membrane

A
  1. Cell signalling
  2. Selective transport
  3. Excretion of waste
  4. Structural support
23
Q

Exocytosis

A

Vesicles release contents out of the cell

24
Q

Endocytosis

A

Vesicles release contents into the cell

25
Q

Aquaporins

A

Aquaporins are integral membrane pore proteins.

AKA: water channels

26
Q

Pinocytosis

A

The ingestion of LIQUID into a cell by the budding of small vesicles from the cell membrane

27
Q

Phagocytosis

A

The ingestion of a SOLID into the cell

e.g. ingestion of bacteria

28
Q

Active Transport examples

A

Endocytosis

Exocytosis

Receptor Mediated Transport

29
Q

Types of osmosis

A

Hypotonic

Hypertonic

Isotonic

30
Q

Why are small cells more efficient at diffusion?

A

They have a HIGH SA:V ratio

31
Q

What size cells are most efficient at diffusion?

A

Small cells

32
Q

When an object is very small, what is its SA:V ratio like?

A

It has a large SA:V ratio

33
Q

When a cell grows, what happens to its SA:V ratio?

A

Its volume increases at a greater rate that its surface area.

Therefore, its SA:V ratio decreases.

34
Q

How might a cell increase its SA:V ratio?

A
  • long thin shape / elongated shape. e.g. nerve cells
  • folding the surface of the object / cell membrane. e.g. villi of the lining in the small intestines
  • plant cells are larger than animal cells, and have a large vacuole which pushes organelles to the edge of the cell where they get regular access to resources
35
Q

Are the heads in the cell membrane hydrophilic or hydrophobic?

A

Hydrophilic

36
Q

Are the tails in the cell membrane hydrophilic or hydrophobic?

A

Hydrophobic

37
Q

What do the hydrophobic tails and hydrophilic heads make?

A

A phospholid bilayer

Biology - TPHS (6 decks)

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