BCH210 Lecture 7 Questions With
Complete Solions
How does membrane formation occur? correct answer: decrease
in ionic bond with water
What are the main functions of the cell membrane? correct
answer: - barrier regulating the import and export of essential
molecules
- Compartmentalization of specialized processes increases
cellular efficiency.
- modulates cell-cell recognition due to the presence of
glycoproteins and glycolipids.
- Signalling across the membrane is mediated by proteins and
lipids.
What is the fluid mosaic model? correct answer: Fluid' -
membrane components can move quite rapidly in the plane of
the membrane.
'Mosaic' - diverse mixture of lipids, proteins and carbohydrates
What are recent modifications made to the fluid mosaic model?
correct answer: the movement of lipid and membrane proteins
differs significant in samples of pure lipids vs. biological
membranes.
Why are biological membranes describe as asymmetrical?
correct answer: - The two leaflets of the membrane have very
different lipid and protein compositions.
, - addition of sugars to lipids and proteins is a form of post-
translational modification mediated by enzymes and is important
for membrane insertion and cell recognition.
- The movement of lipids from one leaflet to the other is very
slow.
- Flip-flow diffusion of polar/charged groups across the
hydrophobic membrane interior is energetically unfavorable.
Why is the movement of lipids from one leaflet to the other is
very slow? correct answer: because of the presence of the polar
head group
What mediates membrane asymmetry? correct answer: enzymes
Enzymes that mediate membrane asymmetry correct answer:
Flippase
Floppase
Scramblase
What does flippase do? correct answer: - moves PE and PS
from outer to inner cytosolic leaflet
- ATP dependent
What does floppase do? correct answer: - moves phospholipids
from cytosolic to outer leaflet
- ATP dependent
What does scramblase do? correct answer: - moves lipids in
either direction, toward equilibrium
-moves lipids down their concentration gradient
- ATP independent
Complete Solions
How does membrane formation occur? correct answer: decrease
in ionic bond with water
What are the main functions of the cell membrane? correct
answer: - barrier regulating the import and export of essential
molecules
- Compartmentalization of specialized processes increases
cellular efficiency.
- modulates cell-cell recognition due to the presence of
glycoproteins and glycolipids.
- Signalling across the membrane is mediated by proteins and
lipids.
What is the fluid mosaic model? correct answer: Fluid' -
membrane components can move quite rapidly in the plane of
the membrane.
'Mosaic' - diverse mixture of lipids, proteins and carbohydrates
What are recent modifications made to the fluid mosaic model?
correct answer: the movement of lipid and membrane proteins
differs significant in samples of pure lipids vs. biological
membranes.
Why are biological membranes describe as asymmetrical?
correct answer: - The two leaflets of the membrane have very
different lipid and protein compositions.
, - addition of sugars to lipids and proteins is a form of post-
translational modification mediated by enzymes and is important
for membrane insertion and cell recognition.
- The movement of lipids from one leaflet to the other is very
slow.
- Flip-flow diffusion of polar/charged groups across the
hydrophobic membrane interior is energetically unfavorable.
Why is the movement of lipids from one leaflet to the other is
very slow? correct answer: because of the presence of the polar
head group
What mediates membrane asymmetry? correct answer: enzymes
Enzymes that mediate membrane asymmetry correct answer:
Flippase
Floppase
Scramblase
What does flippase do? correct answer: - moves PE and PS
from outer to inner cytosolic leaflet
- ATP dependent
What does floppase do? correct answer: - moves phospholipids
from cytosolic to outer leaflet
- ATP dependent
What does scramblase do? correct answer: - moves lipids in
either direction, toward equilibrium
-moves lipids down their concentration gradient
- ATP independent
