What are some membrane properties? correct answer: - Composed of lipid bilayer that are impermeable to polar or charged molecules.
- Hydrophobic effect drives membrane formation of amphipathic molecules
- Membranes are asymmetric and composed of lipids and proteins
- Membrane proteins play ke...
BCH210 - Week 4 Questions With
Complete Solutions
What are some membrane properties? correct answer: -
Composed of lipid bilayer that are impermeable to polar or
charged molecules.
- Hydrophobic effect drives membrane formation of
amphipathic molecules
- Membranes are asymmetric and composed of lipids and
proteins
- Membrane proteins play key roles in transport of molecules
and transduction of info across the membrane
What are essential membrane functions? correct answer: - Act
as a barrier regulating import and export of essential molecules
- Compartmentalisation increases cellular efficiency
- Membrane modulates cell-cell recognition due to glycoproteins
and glycolipids
- Signalling across membrane mediated by proteins and lipids
Why is membrane fluidity important? correct answer: - Proteins
carry out the movement of molecules across membrane
- Signals may also be transmitted across membrane
- Conformational change is important for mediating these
processes
What plays a role in membrane fluidity? correct answer: Lipids
and cholesterol
, What is the fluid mosaic model? correct answer: Membrane
components can move rapidly in plane of membrane. Diverse
mixture of lipids, proteins and carbohydrates. Not as fluid as
proposed originally.
Biological membranes are asymmetrical correct answer: - The
two leaflets of the membrane have very different lipid and
protein compositions.
- The presence of different lipids or proteins allow for specific
interactions on each leaflet of the membrane.
- 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 unfavourable..
How are glycoproteins/lipids attached? correct answer: attached
via enzymes (transferases), PTM, found on exterior of cells and
contribute to cell-cell recognition
What does flippase do? correct answer: actively flips
phosphatidylserine and phosphatidylethanolamine from
extracellular to cytosolic leaflet (P-type and ATPase)
What does floppase do? correct answer: moves phospholipids
from cytosolic to outer leaflet (ABC Transporter)
What does scramblase do? correct answer: moves lipids in
either direction, toward equilibrium
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