Cell Structure and Function Exam 1 Questions
and Verified Answers
Eukaryotic vs Prokaryotic Correct Answer: E - Membranous subcompartments (organelles), linear
chromies
P - None, circular chromies
Cell Correct Answer: A typical mammalian cell is 10-100 micrometers across
4 Classes of Macromolecules Correct Answer: Proteins (made of amino acids)
Carbs (made of sugars)
Nucleic acids (made of nucleotides)
Lipids (fatty acids and others)
Plasma Membrane Correct Answer: Barrier between cytoplasm and outside
1. virtually impermeant to charge and polar molecules
2. selective transport
3. surface area for protein catalyzed rxns
Bilayer Correct Answer: Head - Polar, hydrophilic
Tail - Nonpolar, hydrophobic
LARGE, POLAR, OR BOTH - can't get thru bilayer w/o help from protein
Passive and Active Transport Correct Answer: Passive: down concentration gradient, high to low
concentration, driving force is gradient
Active: against concentration gradient, low to high concentration, requires ENERGY
, Fluid Mosaic Model Correct Answer: Integral (transmembrane) proteins cross the bilayer
Peripheral membrane proteins attach to one side of bilayer
3 Classes of Membrane Lipids Correct Answer: Phosphoglycerides, Sphingolipids, Cholesterols
Cholesterol - controls the bilayer rigidity and H2O permeability
They influence the structure and function of membrane
Thickness, curvature, lipid rafts
Ion Channel (channels are faster than pumps), NOT A TRANSPORTER Correct Answer: A protein
complex that forms a selective pore thru the bilayer
(molecules (ions) flow down concentration gradient thru channel)
Channels Are Usually Gated (something opens them) Correct Answer: Change in membrane potential -
Voltage gated
Binding of ligand - Ligand gated
Change in membrane tension - Stretch activated
General Categories of Membrane Transport Proteins Correct Answer: Active Transport - ATP powered
pumps, symporter, antiporter
Passive Transport - Ion channel, uniporter (facilitated diffusion, transport is specific)
Pumps (ATPase) Active Transport Correct Answer: The NA+/K+ ATPase of plasma membrane
Use energy of ATP hydrolysis to move both Na and K against gradient
Active Transport Correct Answer: Pumps use ATP as energy source
Cotransporters use energy associated with one molecule's gradient to move another molecule against its
gradient
Cell's Charge Correct Answer: Negative relative to the outside
and Verified Answers
Eukaryotic vs Prokaryotic Correct Answer: E - Membranous subcompartments (organelles), linear
chromies
P - None, circular chromies
Cell Correct Answer: A typical mammalian cell is 10-100 micrometers across
4 Classes of Macromolecules Correct Answer: Proteins (made of amino acids)
Carbs (made of sugars)
Nucleic acids (made of nucleotides)
Lipids (fatty acids and others)
Plasma Membrane Correct Answer: Barrier between cytoplasm and outside
1. virtually impermeant to charge and polar molecules
2. selective transport
3. surface area for protein catalyzed rxns
Bilayer Correct Answer: Head - Polar, hydrophilic
Tail - Nonpolar, hydrophobic
LARGE, POLAR, OR BOTH - can't get thru bilayer w/o help from protein
Passive and Active Transport Correct Answer: Passive: down concentration gradient, high to low
concentration, driving force is gradient
Active: against concentration gradient, low to high concentration, requires ENERGY
, Fluid Mosaic Model Correct Answer: Integral (transmembrane) proteins cross the bilayer
Peripheral membrane proteins attach to one side of bilayer
3 Classes of Membrane Lipids Correct Answer: Phosphoglycerides, Sphingolipids, Cholesterols
Cholesterol - controls the bilayer rigidity and H2O permeability
They influence the structure and function of membrane
Thickness, curvature, lipid rafts
Ion Channel (channels are faster than pumps), NOT A TRANSPORTER Correct Answer: A protein
complex that forms a selective pore thru the bilayer
(molecules (ions) flow down concentration gradient thru channel)
Channels Are Usually Gated (something opens them) Correct Answer: Change in membrane potential -
Voltage gated
Binding of ligand - Ligand gated
Change in membrane tension - Stretch activated
General Categories of Membrane Transport Proteins Correct Answer: Active Transport - ATP powered
pumps, symporter, antiporter
Passive Transport - Ion channel, uniporter (facilitated diffusion, transport is specific)
Pumps (ATPase) Active Transport Correct Answer: The NA+/K+ ATPase of plasma membrane
Use energy of ATP hydrolysis to move both Na and K against gradient
Active Transport Correct Answer: Pumps use ATP as energy source
Cotransporters use energy associated with one molecule's gradient to move another molecule against its
gradient
Cell's Charge Correct Answer: Negative relative to the outside
