Chapter 7 - Membranes

Question 1

What are membranes’ structures mostly made up of?

Answer 1

phospholipids and proteins

Question 2

Briefly describe the structure of a lipid bilayer?

Answer 2

They are made up of two similar layers attached
It’s mainly made up of fatty acids tails with the phosphate group as its head.
The fatty acids point inwards and the heads point outwards towards the water

Question 3

How do membranes form in a cell?

Answer 3

They form spontaenously; They form naturally because the fatty acids are so hydrophobic that they automatically form a bilayer

Question 4

How are the proteins embedded into the cell membrane?

Answer 4

They are stacked between the phospholipid bilayer chains

Question 5

Why do proteins not move?

Answer 5

Because they are attached by fibers on the extracellular matrix side and also to the cytoskeletons on the inside

Question 6

Can a phospholipid move around in a lipid bilayer

Answer 6

Yes, there are two ways it can move around

Question 7

Briefly describe how the phospholipids can move around? Is it common for them to move around?

Answer 7

1. Lateral movement : Two phospolipids situated next to each other switch positions
2. Flip-Flopping : Two phospholipids across each other are switching spots with one another

It’s common for phospholipids to laterally move but it’s more rare for them to flip-flop

Question 8

Are membranes very fluid?

Answer 8

Yes, membranes are very fluid

Question 9

Can membrane’s fluidity vary?

Answer 9

It can be influenced by various factors

Question 10

How can we influence a membrane’s fluidity?

Answer 10

To increase the fluidity:
- we can raise the temperature
- we can add more unsaturated fatty acids

To decrease the fluidity:
- we can add more saturated fatty acids

Question 11

how can we change fluidity using chloresterol?

Answer 11

adding chloresterol to lipid bilayers changes the temperature depending on the temperature.
At 37 or less degrees : there’s more fluidity
At 37 or more degrees : there’s less fluidity

Question 12

Are membranes’ functions just to form border around cells?

Answer 12

No, the proteins on the membrane determine the membrane’s functions

SO THEY ARE CALLED MEMBRANE PROTEINS

Question 13

List and explain the different types of membrane proteins

Answer 13

1. Peripheral Proteins : bound to the surface
2. Integral Proteins : are embedded into the** hydrophobic region**