Membrane Fluidity

Question 1

What is the basic idea of the fluid membrane model (fluid mosaic)

Answer 1

-Membrane at physiological temperature is fluid & dynamic

Question 2

What are the fluid abilities a result of?

Answer 2

• Properties of Phospholipids, triglycerides, & fatty acids
• Fatty acids= by way that P.lipids & triglycerides stick to eachother
• It is the natural relationship between the fluidity of a membrane (composed of p.lipids) & fluidity of triglycerides

Question 3

What does membrane fluidity resemble?

Answer 3

• Oil at room temperature

- More like triglyceride w/ fatty acids that are unsaturated= move as a liquid

Question 4

What is the relationship between membrane fluidity & temperature?

Answer 4

• As the temperature increases, the membrane becomes more fluid
• As the temperature decreases, the membrane becomes less fluid

Question 5

How did Brian & Eddiden measure fluidity?

Answer 5

• Experimented w/ human cell that was colored red & a mouse cell that was colored green (takes 10-20 mins to mix membrane proteins)
• If both cells fused together & the colors mixed, then the membrane is fluid
• If the colors don’t mix then the membrane is static

Question 6

How can cells maintain their desired fluidity of their membranes?

Answer 6

• By changing their fatty acids in the phospholipids

- It is necessary since a cell can function ONLY at a limited range of membrane fluidity

Question 7

How would a cell increase it’s membrane fluidity?

Answer 7

-Adding Unsaturated fatty acids w/ shorter fatty acid chains

Question 8

How would a cell Decrease it’s membrane fluidity?

Answer 8

-Adding Saturated fatty acids w/ longer fatty acid chains

Question 9

How would a cell reach their goal to keep the membrane fluidity constant?

Answer 9

• Actively change it’s membrane components to compensate for environmental temperature changes
• Cells from different organisms from different natural temperatures (or cells from same organisms w/ same natural temps) are gonna have different membrane components

Question 10

How will a cell respond to temperature Decrease?

Answer 10

• Since temperature is decreased, the membrane is now LESS fluid so the cells job is to make it MORE fluid
• Cell can make new Phospholipids w/ more unsaturated fatty acids w/ shorter fatty acid chains
• Some cells can also use “Desaturase” Enzymes to alter the fatty acids that are already present by introducing a double bond to increase fluidity

Question 11

How will a cell respond to temperature Increase?

Answer 11

-They can make Phospholipids w/ fewer unsaturated fatty acids w/ longer fatty acid chains

Question 12

What about cells at Naturally higher temperatures?

Answer 12

-They’re going to have more saturated fatty acids & longer fatty acid chains

Question 13

What about cells at Naturally lower temperatures?

Answer 13

-They’re going to have more unsaturated fatty acids w/ shorter fatty acids chains