5.2. FACTORS AFFECTING MEMBRANE STRUCTURE

Question 1

What is the experiment that shows cell surface proteins are mobile?

Answer 1

Form a HETEROKARYON (different chromosomes)
SEE REVISION POSTER

Question 2

How many carbon atoms do fatty chains in phospholipids/glycolipids contain?

Answer 2

-between 16/20 with 16 and 18 being the most common

Question 3

How saturated are fatty acids?

Answer 3

Can be unsaturated or saturated - with the configuration of double bonds nearly always ‘cis’

Question 4

How does the length and degree of unsaturated fatty acids affect fluidity?

Answer 4

Create a kink, preventing the fatty acids from packing together there as tightly, thus increasing fluidity

Question 5

What does saturated mean?

Answer 5

Contains single bonds between carbon atoms

Question 6

What does unsaturated mean?

Answer 6

Contains double bonds between carbon atoms

Question 7

How do some organisms regulate the fluidity of their cell membranes?

Answer 7

By altering lipid composition - this is called HOMEOVISCPUS ADAPTATION
-this is especially important in poikilothermic organisms

Question 8

What is the general trend to do with saturated/unsaturated fatty acids and temperature?

Answer 8

An increase in saturated fatty acids at higher temperatures.
An increase in unsaturated fatty acids at lower temperatures.

Question 9

What dimension do phospholipids move in?

Answer 9

2D

Question 10

What does increasing the temperature do to phospholipids?

Answer 10

-increase kinetic energy
-phospholipids will move more
Initially, this increases fluidity and permeability, however this will eventually DISRUPT the bilayer

Question 11

What happens to membrane proteins at higher temperatures?

Answer 11

they will denature, affecting plasma membranes ability to control the movement of molecules/ions across it.

Question 12

What are organic solvents?

Answer 12

-can be non polar or polar
-disrupts structure and function of membranes as they dissolve them

Question 13

What are some examples of organic solvents

Answer 13

Polar= ethanol
Non polar= benzene

Question 14

To what extent does alcohol (organic solvent) disrupt membranes?

Answer 14

water floods into the cell - this is why it is used as a disinfectant
e.g. alcohol based sanitiser disrupts lipid envelopes of covid-19 virus

Question 15

What determines whether a substance can dissolve in water?

Answer 15

Whether it can hydrogen bond or not or if it has full charges

Question 16

What is a colorimeter?

Answer 16

a device used in colorimetry that measures absorbance of particular wavelengths (colours) of light by a specific solution

Question 17

Why are colorimeters commonly used?

Answer 17

to determine the concentration of a known solute in a given solution by the application of the Beer-Lambert Law

Question 18

What is the Beer-Lambert Law?

Answer 18

states that the concentration of a solute is proportional to the absorbance