Factors affecting membrane structure

Question 1

What are the role of membranes?

Answer 1

• They control the passage of different substances in and out of he cells (and organelles)

Question 2

What happens if membranes lose their structure?

Answer 2

• They lose control the passage of substances and the cell process will be disrupted.

Question 3

What happens when temperature is increased?

Answer 3

• The phospholipids will have more kinetic energy and will move more.
• This makes the membrane more fluid and it begins to lose its structure.
• If the temperature continues to increase, the cell will eventually break down completely.

Question 4

What happens to loss of the structure of the membrane?

Answer 4

• Increases permeability of the membrane making it easier for the particles to cross it.

Question 5

CARRIER AND CHANNEL PROTEINS

Answer 5

• They will be denatured at higher temperatures
• These proteins are involved in transport across the membrane so as they denature, membrane permeability will be affected.

Question 6

How does cooling and freezing a membrane will affect its structure?

Answer 6

• Freezing affects the membranes lipids, proteins and nucleic acid by changing the hydrophobic and hydrophillic interactions determining the structure and the function

Question 7

SOLVENTS

Answer 7

• Water, a polar solvent is essential in the formation of the phospolipid bilayer

Question 8

NON-POLAR tails

Answer 8

• These are orientated away from the water, forming a bilayer with a hydrophobic core
• The charged phosphate heads interact with the water, helping to keep the bilayer intact

Question 9

ORGANIC SOLVENTS

Answer 9

• Many organic solvents are less polar than water (e.g. alcohols)
• Organic solvents will dissolve the membranes, disrupting the cell
• Alcohols dissolve the membranes of bacteria in wound, killing them and reducing the risk of infection.

Question 10

LESS CONCENTRATED SOLUTIONS OF ALCOHOL

Answer 10

• They do not dissolve the membranes.
• Non-polar alcohol molecules can enter the cell membrane & the presence of these molecules between the phospholipids will disrupt the membranes.

Question 11

What happens when the MEMBRANE IS DISRUPTED?

Answer 11

• It becomes more fluid and more permeable
• When neuronal membranes are disrupted, nerve impulses are no longer transmitted as normal.