Cellular Functions 2 Flashcards
3 substances with higher concentration inside the cell than out
potassium, magnesium, and amino acids
3 substances with lower concentrations inside the cell than out
sodium, chloride, and calcium
passive membrane transport
does not require energy
molecules move down a concentration gradient
two types: diffusion and osmosis
diffusion
net movement of ions or molecules from areas of greater concentration to areas of lesser concentration
uses concentration gradient and kinetic energy
factors that influence diffusion
temp goes up, kinetic energy goes up, rate of diffusion goes up
big difference in concentration, faster rate of diffusion
simple diffusion
molecules move unassisted between phospholipid molecules
small and non polar solutes like gasses and urea
dependent on concentration gradient
facilitated diffusion
transport process for small charged or polar solutes
needs assistance from plasma membrane proteins
two types: channel-mediated diffusion and carrier-mediated diffusion
channel-mediated diffusion
movement of small ions through water filled protein channels
important for nerve and muscle cells
use leak and gated channels
carrier-mediated diffusion
small polar molecules assisted across membrane by carrier protein
substance binds which causes shape change in carrier protein
allows substance to move down gradient
3 types of gaited channels
voltage, chemically, and mechanically gated
osmosis
passive movement of water through the plasma membrane
does not allow solutes to move through
happens due to differences in water concentration on either side of membrane
can go between molecules of bilayer or through aquaporins
osmotic pressure
pressure exerted by movement of water across semipermeable membrane
due to different in solute concentration
hydrostatic pressure
pressure exerted by a fluid on the inside wall of its container
tonicity
ability of solutions to change the volume or pressure of a cell by osmosis
isotonic solution
cytosol and solution have same concentration of solutes
no net water movement
hypotonic solution
solution has lower concentration of solutes and more water in cytosol
cells will lyse as water goes inside the cell
hypertonic solution
solution has higher concentration of solutes and less water in cytosol
crenation: cells shrink
active transport
movement of solute against its concentration gradient
two types: primate and secondary active transport
primary active transport
type of transport that uses energy from breaking a phosphate bond in ATP
ex. ion pumps
secondary active transport
moves substances against gradient
first uses electrical chemical gradient energy then eventually will use ATP to rid the cell of built up ions
two types: symport and antiport
symport secondary active transport
two substances are moving in the same direction
antiport secondary active transport
two substances are moving in opposite directions
vesicular (bulk) transport
transporting large substance across the membrane in a vesicle
requires energy
exocytosis and endocytosis
exocytosis
large substances secreted from cell in a vesicle
vesicle fuses with plasma membrane and contents are released outside of the cell
requires ATP
endocytosis
cell uptake of large substances from external environment
pocket forms in membrane then pinches off with substances inside
phagocytosis
cellular eating
occurs when cell engulfs large particles external to cell
pinocytosis
cell drinking
internalization of droplets of interstitial fluid containing dissolved solutes
explain receptor-mediated endocytosis
ligand binds to surface receptors in clathrin coated pits
myosin and actin help pinch off the vesicle into the cell
enables the cell to obtain bulk quantities of substances
ex. transporting cholesterol from blood to inside the cell
explain familial hypercholestermia
inherited genetic disorder where there is a defect in the LDL receptor so cholesterol cannot be taken out of the blood as easily
results in too much cholesterol in the blood which can build up in the arteries and cause atherosclerosis