Forces Across Membranes 1 Flashcards

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1
Q

In simple terms, what does the cell membrane do?

A

Seperates the ECF and the ICF, is responsible for the composition difference between the two

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2
Q

Give an example of some concentration differences between the ECF and the ICF?

A

Na+ > in ECF

K+ > in ICF

Cl- > in ECF

HCO3- > in ECF

Phosphate/Sulphate > in ICF

Protein > in ICF

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3
Q

How do cell membranes acts as a selective barrier?

A

Permeable and impermeable to different substances

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4
Q

What substances can freely cross the cell membrane?

A

O2

Nutrients

CO2

Waste

H2O

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5
Q

What substances cannot cross the cell membrane and the capillary wall?

A

Ions cannot cross the cell membrane

Plasma proteins cannot cross the capillary wall

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6
Q

Does permeability of the cell membrane change at different times?

A

Yes

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7
Q

How are membranes dynamic?

A

They are constantly being formed, changed or dismantled

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8
Q

What forms most of the cell membrane?

A

Thin layer of phopholipids as a bilayer

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9
Q

Why are membranes flexible?

A

Fatty acids behave like oil

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10
Q

What could happen to membranes if they are overstretched?

A

They could rupture

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11
Q

Why are membranes a good insulator against electrical charge?

A

They prevent the passage of electrons

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12
Q

How to proteins and carbohydrates relate to membranes?

A

Membranes are embedded with proteins and associated with carbohydrates

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13
Q

Are membrane carbohydrates intra or extra cellular

A

Extracellular, they are linked to proteins and lipid

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14
Q

What are the carbohydrates of the cell membrane linked to?

A

Proteins and lipids

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15
Q

What are the carbohydrates of the membrane important for?

A

Cell-cell communication

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16
Q

What are glycoproteins?

A

Proteins with carbohydrate groups attatched to the polypeptide chain

17
Q

What are glycolipids?

A

Lipids with a carbohydrate group attatched

18
Q

What are the four classes of membrane proteins?

A

Receptor

Transporters (carrier and channel proteins)

Enzymes

Peripheral proteins

19
Q

What are integral membrane proteins?

A

Proteins which are integrated into the structure of the membranes, such as receptors, transporters and enzymes

20
Q

Are peripherial proteins embedded into the membrane?

A

No, they are associated with the membrane byt not embedded in it

21
Q

What are receptors?

A

Allows communication of an extracellular signal to an intraceullular space to create an intracellular response

22
Q

Why is the cellular response of a receptor specific?

A

Not all receptors are present on all cells, with receptors being unique to different substances

23
Q

What are transporters?

A

Proteins which allow movement of ions or molecules across the membrane

24
Q

What are the two types of transporters?

A

Channel proteins

Carrier proteins

25
Q

How do channel proteins operate?

A

They create a pore through the membrane which molecules (usually water and ions) can flow through

26
Q

What are the two types of channel proteins?

A

Open (water) or gated (ions) which open in response to signals

27
Q

How do carrier proteins work?

A

They do not create a continuous pore, they are only open at one side at any time

28
Q

What is an enzyme?

A

Catalyses reactions on the cell membrane

29
Q

What are enzymes often associated to?

A

Receptors

30
Q

What are some roles of peropheral proteins?

A

Maintain structure of cells by anchoring the membrane to intracellular cytoskeleton

Attatches cells to the extracellular matrix

Perform signilling functions within cells

31
Q

Give some examples of how membranes differ in their protein content to suit their function?

A

Myelin 18% protein as lipids are better for insulation

Most cells are 50% proteins

Membranes involved in energy transduction such as mitochondria inner membrane are 75% proteins