BIOL 302 Exam 3Latest 2025/2026
Questions and Correct Answers Graded
A+|Assured Success
What are the 5 building blocks of a Phosphatidylcholine molecule? - CORRECT
ANSWER-choline (hydrophilic head), phosphate, glycerol, 2 hydrocarbon chains
what other components can be found within the phospholipid bilayer? -
CORRECT ANSWER-phosphatidylcholine, cholesterol, glycolipids
,Why are cell membranes important? - CORRECT ANSWER-receiving
information, capacity for movement and expansion, import and export of
molecules; act as selective barriers and allow for compartmentalization in
eukaryotic cells
Different functions of cell membranes - CORRECT ANSWER-bring nutrients in,
pump waste products out, protect internal organelles from harmful agents in
extracellular environment, sense activities/ changes in extracellular environment,
move around to change the shape of the cell
nucleus and mitochondria enclosed by - CORRECT ANSWER-2 membranes
what affects the fluidity of the bilayer - CORRECT ANSWER--temperature
-types of hydrocarbons (phospholipid composition)
-saturated vs. unsaturated hydrocarbon tails
-unsaturated fatty acid tails increase the fluidity
-short tails increase the fluidity of the membrane
What are scramblases and flippases? - CORRECT ANSWER-scramblases:
transfer newly synthesized phospholipid molecules to opposite monolayer so
entire bilayer expands; in the ER; transfer random phospholipids
, flippases: help maintain asymmetry of plasma membrane in animal cells; in the
golgi and other cell membranes; transfer specific phospholipids
What are some different types of membrane proteins? - CORRECT ANSWER-
transporters, ion channels, anchors, receptors, enzymes
How can membrane proteins associate with the bilayer? - CORRECT ANSWER-
transmembrane, monolayer associated, lipid-linked, protein-attached
How do we break up a lipid bilayer? What could this be used to do
experimentally? - CORRECT ANSWER-broken up by detergents like Triton X-
100 and SDS; used to solubilize and reconstitute functional membrane proteins
The cell cortex - CORRECT ANSWER-meshwork of fibrous proteins that is
attached to the cytosolic face of the membrane that determine the shape of a cell
and mechanical properties; human red blood cell cortex has distinctive flattened
shape
The meshwork which forms the cell cortex - CORRECT ANSWER-meshwork
made of spectrin (long, thin, flexible rod); spectrin dimers linked together in a
netlike meshwork
Questions and Correct Answers Graded
A+|Assured Success
What are the 5 building blocks of a Phosphatidylcholine molecule? - CORRECT
ANSWER-choline (hydrophilic head), phosphate, glycerol, 2 hydrocarbon chains
what other components can be found within the phospholipid bilayer? -
CORRECT ANSWER-phosphatidylcholine, cholesterol, glycolipids
,Why are cell membranes important? - CORRECT ANSWER-receiving
information, capacity for movement and expansion, import and export of
molecules; act as selective barriers and allow for compartmentalization in
eukaryotic cells
Different functions of cell membranes - CORRECT ANSWER-bring nutrients in,
pump waste products out, protect internal organelles from harmful agents in
extracellular environment, sense activities/ changes in extracellular environment,
move around to change the shape of the cell
nucleus and mitochondria enclosed by - CORRECT ANSWER-2 membranes
what affects the fluidity of the bilayer - CORRECT ANSWER--temperature
-types of hydrocarbons (phospholipid composition)
-saturated vs. unsaturated hydrocarbon tails
-unsaturated fatty acid tails increase the fluidity
-short tails increase the fluidity of the membrane
What are scramblases and flippases? - CORRECT ANSWER-scramblases:
transfer newly synthesized phospholipid molecules to opposite monolayer so
entire bilayer expands; in the ER; transfer random phospholipids
, flippases: help maintain asymmetry of plasma membrane in animal cells; in the
golgi and other cell membranes; transfer specific phospholipids
What are some different types of membrane proteins? - CORRECT ANSWER-
transporters, ion channels, anchors, receptors, enzymes
How can membrane proteins associate with the bilayer? - CORRECT ANSWER-
transmembrane, monolayer associated, lipid-linked, protein-attached
How do we break up a lipid bilayer? What could this be used to do
experimentally? - CORRECT ANSWER-broken up by detergents like Triton X-
100 and SDS; used to solubilize and reconstitute functional membrane proteins
The cell cortex - CORRECT ANSWER-meshwork of fibrous proteins that is
attached to the cytosolic face of the membrane that determine the shape of a cell
and mechanical properties; human red blood cell cortex has distinctive flattened
shape
The meshwork which forms the cell cortex - CORRECT ANSWER-meshwork
made of spectrin (long, thin, flexible rod); spectrin dimers linked together in a
netlike meshwork
