Chp 5-7 Test Flashcards
what factors might affect membrane permeability
of unsaturated and saturated fatty acid tails
temperature: high temp may denature proteins making it more permeable or cool temp will cause the membrane to solidify (if the temperature changes slightly it will stay fluid because it has unsaturated fatty acid tails that do not let them pack too tight)
amount of proteins found in the membrane: larger amount then more molecules can move in and out
pH: may denature some of the proteins
examples of passive transport
NO ENERGY: diffusion, osmosis, facilitated diffusion
diffusion
tendency for molecules to spread out evenly in a defined space; random thermal movement (high to low concentration) EX: dropping food color into water NO ENERGY NEEDED
osmosis
diffusion of water across a membrane structure EX: water entering a cell (high to low concentration) NO ENERGY NEEDED
facilitated diffusion
need a transport channel protein with a pathway because the molecules are either small and polar or too large to fit through the membrane without the transport channel protein (high to low concentration) EX: aquaporins NO ENERGY NEEDED
examples of active transport
NEED ENERGY (ATP): sodium/potassium pump, endocytosis, exocytosis
sodium/potassium pump
pump sodium against the gradient and out of the cell and bring potassium into the cell. ATP phosphorylates the transport protein causing it to change its shape
endocytosis
movement of molecules or liquids into the cell creating a vesicle using energy EX: a macrophage digesting a viral infected cell (two types, pino- and phagocytosis)
exocytosis
taking a vessel that the golgi apparatus has made and the vessel merges with the cell’s plasma membrane to empties its contents outside the cell EX: signal molecules that the cell molecules that is releasing a hormone into the blood stream
hypertonic
a solution that has higher solutes but lower water compared to whatever is in the solution. The cell will shrink and shrivel up.
hypotonic
a solution that has lower solutes but higher water compared to whatever is in the solution. The cell will expand-do not worry if a plant cell, worry if animal bc no cell wall and might burst.
isotonic
solute concentration in solution is equal to solute concentration in the cell. water concentration in solution is equal to the water concentration in the cell
what happens when signal molecules bind to G-coupled protein
G-couples protein receptors are sitting in the membrane. A signal molecule has to bind to the protein receptor-specific for it, has the same shape. Causing the G-protein/GDP to be activated by receiving a phosphate and forming GTP. Then the G-protein travels along the inside of the membrane using microtubules and ATP. It then binds to an enzyme (Adenyl cylcase) that is also in the membrane and activate it by changing its shape. When the signal molecule detaches the enzyme deactivates and goes back to its original shape and the G-protein loses a phosphate and is inactive.
what types of signal molecules pass easily through membranes
small molecules (O, CO2) or non polar molecules (steroids, estrogen). their receptors are in the cytoplasm
yeast mating factors and how they work
Yeast a creates a signal molecule called alpha and the alpha yeast will create a signal molecule called a. They release them through exocytosis. The signal molecules of alpha will bond to the alpha yeast, the signal molecules of a will bond to the alpha a. When they bind they signal each other to come together. Their nuclei together.
