Lecture 6:

Question 1

Where are phospholipids made in the cell?

Answer 1

Made by enzymes located on the cytosolic side of the Smooth ER

Question 2

How are newly made lipids inserted into a membrane?

Answer 2

Enzymes insert new phospholipids only on cytosolic side of ER membrane causing asymmetrical distribution

Question 3

Scramblase

Answer 3

Scramblase is not an enzyme but translocator that moves random phospholipids from one monolayer to the next to cause symmetrical distribution

Question 4

Where is Scramblase found?

Answer 4

ER and plasma membrane

Question 5

Flipppase

Answer 5

move specific phospholipids from one monolayer to the other in the Golgi membrane → initiate and maintain phospholipid asymmetry

Question 6

Which organelles contain flippase?

Answer 6

Found in Golgi membrane, plasma membrane, and other internal membranes

Question 7

Flippase do not transfer glycolipids to ________

Answer 7

Cytosolic Face

Question 8

Are plasma membranes symmetrical or asymmetrical in respect to phospholipids?

Answer 8

Asymmetrical

Question 9

Transport vesicles

Answer 9

deliver proteins and membrane lipids synthesized in ER to the golgi apparatus, plasma membrane, and other organelles

Question 10

Describe how the ER and Golgi Apparatus work together to assemble membranes in a cell

Answer 10

Phospholipid synthesis adds to cytosolic half of the ER bilayer → causes asymmetric distribution
Scramblase catalyzes transfer of random phospholipids from one monolayer to another → Causes symmetric growth to bilayer
In the ER membrane, phospholipids are randomly distributed

In Golgi apparatus, there is deliver of new membrane from the ER
Flippase catalyzes transfer of specific phospholipids to cytosolic monolayer
In the golgi apparatus, other membranes, and phospholipid distribution is asymmetric