Chapter 5 Flashcards
what is a big function of the plasma membrane?
controlling movement in and out of the cell
list three small molecules that can move easily in and out of membranes
water, O2, and H2
if a substance is larger or has a different polarity than the cell membrane, what does the cell use to help it in or out?
special proteins
what are the 4 components of the cell membrane?
- phospholipid bilayer
- embedded proteins: integral and peripheral
- cholestrol
- glycoproteins and glycolipids
what is a peripheral protein?
proteins embedded in the top or bottom of the phospholipid bilayer, don’t go all the way through, nonpolar
what is an integral protein?
proteins that go all the way through the phospholipid bilayer, also called transmembrane proteins, some solid, some hollow, have polar and nonpolar regions
what do the glycoproteins attach to?
the embedded proteins
what are the two parts of phospholipids?
POLAR head, and NONPOLAR tail
what is the spherical structure formed by the polar ad nonpolar properties of phospholipids?
micelles
what are the 5 functions of membrane proteins?
- structure; integrity
- transport; channels for molecules
- self-identity; recognized as you or not you, RBC’s blood type
- communication; send signals and communicate with cell neighbors
- cellular movement (external structures); flagella and cilia are made of microtubule proteins
what are the two main categories of membrane proteins?
integral and peripheral
what is the function of peripheral proteins?
communication and self-identity
what is the function of integral proteins?
transport, some structural support
what is the importance of the plasma membrane?
defines cell boundaries, regulates movement in and out
what are the functions of the plasma membrane?
protection, self-recognition, communication
what is a solvent? definition and example
something that dissolves other things, water
what is a solute? definition and example
something that gets dissolved, NaCl (in water), sugar
what is a solution?
a solvent and its dissolved solute, salt water, sweet tea
what is diffusion?
movement of solutes within a solution down the concentration gradient
what is Brownian motion?
the constant movement, jiggling, and crashing of solutes in response to a concentration gradient
the more concentrated a solution is, will there be more or less solute collisions?
more
how does the concentration gradient of solutes move?
from high solute concentration to low solute concentration, seeking and eventually achieving equilibrium
what happens to the solutes one equilibrium is reached?
there is no more net movement
when two solutions have different concentrations with a membrane separating them, what three conditions are there?
hypertonic, hypotonic, and isotonic
describe a hypertonic solution
very concentrated, more solutes than the other solution
describe a hypotonic solution?
not as concentrated, fewer solutes than the other solution
describe an isotonic solution?
both solutions have equal solute concentrations
how do solutes move?
down the solute concentration gradient, from high to low solute concentration, hypertonic to hypotonic
define selective permeability?
the ability of a membrane to control whether or not a solute can move across
write the formula for rate of diffusion
rate = distance/time
what 6 factors determine the rate of diffusion?
- the higher/steeper the concentration gradient = faster diffusion, slows as equilibrium is approached
- cell surface area, bigger = faster diffusion (to a certain point until too big to reach center of cell)
- travel distance, farther distance = slower diffusion, inverse relationship
- temperature, higher = faster diffusion b/c of Brownian motion, direct relationship
- molecule size, bigger = slower, needs more help
- charge
what is the diffusion of water, typically across a membrane called?
osmosis, and its rules are hella weird
when other solutes can’t move, what molecule can and will?
water, it wants to dissolve everything
what is water’s concentration gradient?
low SOLUTE to high SOLUTE concentration (it wants to dissolve everything), and high WATER concentration to low WATER concentration, so it is still passive transport
what does the direction of osmosis depend on?
water and solute concentration
what type of solution do cells WANT to be in?
isotonic
do isotonic solutions occur often?
no :(
what happens when a cell is placed into a hypertonic solution?
if solutes can’t cross the membrane, water leave the cell to dissolve outside solutes, and cell shrivels
what is cell shriveling called in an animal cell?
crenation
what is cell shriveling called in a plant cell?
plasmolysis, central vacuole will shrink, and cytoplasm will pull away from cell wall to fill the space
what happens when a cell is placed into a hypOtonic solution?
if solutes can’t cross the membrane, water rushes into the cell to dissolve inside solutes, and cell swells and can burst
what is it called when an animal cell swells and bursts?
lysis
can a plant cell burst? why or why not?
no, the cell wall won’t allow it
what is it called when a plant cell swells?
turgid
what does a plant cell look like when it’s turgid?
very full, cell wall may give a little bit, central vacuole is full, cytoplasm is pushed up against cell wall
what happens to red blood cells in a hypertonic solution of 10% salinity?
crenation, water leaves cell, cells can’t travel through bloodstream, blood clots form
ex. dehydraton
what happens to red blood cells in a solution of 0.9% salinity?
they are happy plump donuts!
what happens to red blood cells in a solution of 0% salinity of distilled water?
water rushes in, cells swell and can burst, lysis
what solution is given in IV’s in the hospital?
lactated ringer’s, 0.9% salinity
what are three ways that cells deal with nonisotonic environments?
- extrusion
- isoosmotic regulation
- turgor pressure
describe extrusion
used by protists, which are almost always in a hypotonic environment, contractile vacuoles act like pumps, pumping excess water into a vacuole that is then expelled and dumped into surrounding environment
describe isoosmotic regulation
we do this! kidneys control how much water the body loses when you pee, if dehydrated, water is kept in body and pee is clear, if not dehydrated, some water can be lost, and pee approaches clear
describe turgor pressure
plant cells use this, they store excess water in their central vacuole when in a hypotonic environment
