Transport of Water and Solutes
Which direction does water flow across a selectively permeable membrane?
down the concentration gradient, to the area of higher solute concentration
what are the relative concentrations (high/low) of sodium and potassium inside the cell?
sodium is low, potassium is high
What are the main components of the plasma membrane?
phospholipids, proteins, cholesterol
what are the three types of exocytosis?
phagocytosis, pinocytosis, receptor-mediated endocytosis
what does it mean if a cell is under hypotonic conditions? what will happen to the cell?
the surrounding fluid has lower solute concentration compared to the cell, so water will flow into the cell and the cell will swell and possibly burst (lyse)
What direction is sodium transported? What direction is potassium transported?
sodium is pumped out, potassium is pumped in
What force maintains the lipid bilayer?
hydrophobic attractions
what energy sources can be used to drive active transport?
ATP, PMF, or co-transport with another solute down its gradient
how are plant and animal cells different in relation to turgor pressure?
plant cells have a cell wall so they can withstand higher turgor pressure, and are normally turgid and in hypotonic conditions, while animal cells need to exist in isotonic conditions
When does phosphorylation occur, and what is the effect?
after 3 Na+ bind, phosphorylation occurs and it causes the protein to change shape and open outwards, releasing Na+ and binding 2 K+
What is the difference between saturated and unsaturated fatty acids?
unsaturated fatty acids have a cis double bond which creates a kink
What changes will occur in the cell membrane at warm temperatures?
more saturated fatty acids
What energy source drives the F1F0 ATPase?
proton motive force
What causes the phosphate group to fall off, and what does this change?
The phosphate group falls off after 2 K+ bind, and this causes the protein to return to its original shape and open to the inside of the cell, releasing K+ and binding 3 Na+
How does cholesterol maintain membrane fluidity?
acts as a buffer, limits excess fluidity by holding fatty acids together at warm temperatures and maintains fluidity by preventing tight packing of fatty acids at cool temperatures
what is a main difference between prokaryotic and eukaryotic cells?
prokaryotes have limited or no intracellular membranes
What transporter is involved in the facilitated diffusion of fructose?
Glut-5
What is the importance of the sodium-potassium pump in the cell?
maintains an electrochemical gradient across the cell membrane so the inside of the cell is always negative compared to the outside
Name 3 functions of membrane proteins.
transport, cell-cell recognition, intercellular joining, attachment to cytoskeleton and ECM, enzymatic activity, signal transduction
what is the structure of a triacylglycerol molecule?
a glycerol molecule with three fatty acid chains connected by ester bonds