bio quiz transport

selective permeability

some substances can cross the membrane more easily than others

easy passage across the membrane include

hydrocarbons and co2, o2, n2

difficult passage across the membrane include

sugars, water, ions

what are the two main types of transport across a membrane

passive and active

passive transport

along concentration gradient

active transport

against concentration gradient

difference between passive and active transport

active requires ATP while passive doesn’t

similarities between passive and active

they both move ions and polar molecules

definition of diffusion

passive, natural movement of molecules

diffusion: move from

area of high to low concentration

how does diffusion move down the concentration gradient

down

real life example of diffusion

perfume

facilitated diffusion

diffusion of molecules through the membrane via transport proteins

the categories of transport proteins

channel and carrier

channel proteins are like a

water park

channel proteins are

hydrophilic and are usually gated

aquaporins

specific channel protein for water

carrier protein undergo

conformational changes for substances to pass

osmosis

diffusion of water

osmosis moves from areas of

low solute to high solute

what factors can affect the rate of diffusion

temperature, distance

why do energy not required for facilitated diffusion

because molecules move spontaneously down their concentration gradient

how is structure important to the function of channel proteins

hydrophilic and selective

tonicity

the ability of a solution to cause a cell to gain or lose eater

cells can be three types

isotonic, hypertonic, hypotonic

isotonic

the concentration inside the cell is equal to outside the cell

isotonic is considered

perfect

hypertonic is considered

shrink

hypotonic is considered

burst

hypertonic

cells lose water to their surroundings

hypotonic

cells gain water into the cell

how do plant cells act in a hypotonic solution

work anyway due to turgor pressure

membrane protein pumps

maintains membrane potential

membrane potential

unequal concentration of ions resulting in an electrical charge

examples of pumps

electrogenic pump and proton pump

electrogenic pump

proteins that generate voltage which is used later as an energy source

proton pump

membrane protein that builds up a proton gradient

cotransport

the coupling of a favourable movement substance with an unfavourable movement substance

favourable movement

downhill diffusion

unfavourable movement

uphill diffusion

who uses cotransport

plants use to move sugars and amino acids

exocytosis

the secretion of of molecules out the cell via vesicles

how do vesicles fuse to the membrane

by forming a bilayer

endocytosis

the uptake of molecules from fused vesicles

phagocytosis

when a cell engulfs particles to be digested

pinocytosis

uptake of extracellular fluid

receptor mediated endocyotsis

uptake of specific molecules via solute binding to receptors