Chapter 3 Flashcards
Functions of plasma membrane proteins: channels
water-filled passageway
- highly selective (water soluble can enter, very small)
- can open or close
cell membrane: structure
phospholipid bilayer
- cholesterol - stability
- proteins:
- integral - spanning entire membrane)
- peripheral - sticking out
Functions of plasma membrane: carrier molecules
transport substances in or out that are not free to pass
- only open to one side at a time (not ECF and ICF at the same time)
functions of plasma membrane: membrane bound enzymes
control chemical reactions
ex. Ache
functions of plasma membrane: receptor sites
can bind with extracellular signals
- use lock and key theory (will bind if messenger fits with receptor)
- have to be complementary
- ex. prolactin knows to bind to breast cells cause they fit
functions of plasma membrane: cell adhesion molecules
grip other cells
- allows cells to form tissues and to stick to various things (ex. WBC)
- protrude from plasma membrane
- ex. Cadherin (velcro)
functions of plasma membrane: ID tags
- proteins often with CHOs (glycoproteins)
- helps cells to recognize of the same type
- prevent overgrowth of tissue - “contact inhibition” (once mitosis is filled in all the areas, they stop growth)
passive
does NOT require ATP
- relies on molecular motion
Active
requires ATP
Unassisted
does not require help/assistance
assisted/carrier mediated
needs a carrier molecule (needs help)
diffusion
- unassisted
- the movement of molecules from a high concentration to a low concentration
- molecules move DOWN their concentration gradient
Osmosis
- unassisted
- diffusion of water DOWN its concentration gradient
- high concentration to a low concentration
- osmotic pressure = pulling
- water being pulled toward the higher solute concentration
tonicity
measure of solute concentration
- referring to the solute concentration in the ECF
isotonic
ICF and ECF solute concentration is =
hypotonic
the ECF has a lower concentration of solutes than the ICF
- water is drawn towards higher solute concentration
Hypotonic: The osmotic pressure is ________ the cell; therefore water will tend to ______ the cell due to osmosis
higher in
enter
hypertonic
the ECF has a higher concentration of solutes than the ICF
hypertonic: the osmotic pressure is _________ the cell; therefore water will tend to ______ the cell due to osmosis
higher outside
leave
filtration
the movement of substances through a membrane as a result of a higher hydrostatic of one side of the membrane
- ex. coffee (directing hydrostatic pressure through membrane -> water pushes coffee grounds through filter into the cup)
example of filtration in the body
cells are filtered out of the blood stream
carrier mediated transport
can be active or passive
characteristics that determine the kind and amount of material that can be transferred across the membrane are_______, ________, and ________
specificity
saturation
competition
specificity
shapes match (carrier molecule for amino and another carrier molecule for glucose - shapes have to match)
satuaration
transport maximum (TM) - mini van analogy - can't carry anymore no matter how much it is flooded (wine analogy)
competition
similar molecules compete
facilitated diffusion
substances move from a HIGHER concentration to a LOWER concentration
- requires carrier molecule
- no ATP
- ex. GLUT
does facilitated diffusion require ATP?
No
active transport
moves a substance UP its concentration gradient by using a carrier molecule
- requires ATP
ex. Na+/K+ pump
vesicular transport: 2 types
endocytosis
exocytosis
endocytosis
import
exocytosis
export
Endocytosis: Phagocytosis
cell-eating
- ATP required
- occurring all the time
Endocytosis: Pinocytosis
cell-drinking
Exocytosis
release of secretory products
“ how do we get things out of the cell?”
membrane potential
difference in charges between ICF and ECF or the separation of opposite charges across plasma membrane
membrane potential is measured in ______
mV
resting membrane potential
constant membrane potential present in cells at rest
- separation of charges in a cell at rest
- nerve cell RMP = -70 mV
The cell membrane is more permeable to ___ than to ____
K+
Na+
K+ leaks/diffuses out at a ______ rate
faster
effect of sodium/potassium pump on membrane potential: pumps ______ in and ________ out
2K+
3Na+
passive ______ and the active ________ work together to establish the RMP
diffusion
Na+/K+ pump
nerve and muscle cells are excitable cells and have the ability to __________ in their membrane potential when excited
produce rapid changes
- this gives us nerve impulses and muscle contractions
proteins that span the whole membrane are called what?
integral
where are the peripheral proteins
they stick out
simply state how active transport is different from passive transport
active transport requires ATP and passive transport does not use ATP
is osmosis passive or active
passive
define diffusion
the movement of molecules from a high concentration to a low concentration
define osmosis
high concentration of water ——–> low concentration of water
cells in a hypertonic solution will _____ water as a result of osmosis
lose
water molecules move _____ the higher osmotic pressure
toward
tonicity refers to the solute concentration in the ___
ECF
in carrier mediated transport, we talk about specificity of the molecules. What does this mean?
shapes have to match - lock and key method
what is TM
transport maximum
minivan analogy
how does the example of TM in class about glucose in the urine demonstrate the above
if there is too much glucose in the urine, TM will grab the g molecules and pull them back into the blood stream
membrane potential is defined as
difference in charges between ICF and ECF or the separation of opposite changes across plasma membrane
what two cell types are excitable
nerve and muscle cells
- have ability to produce rapid changes in their membrane potential when excited
resting membrane potential is defined as
constant mp present in cells at rest
resting potential is about ____ mV for the normal cell
-70
so that means that K+ wants to diffuse _____ and Na+ wants to diffuse ___
out
in
how many Na+ are pumped
3 out
how many K+ are pumped
2 IN
the cell membrane is leakier to ___ than to ___
K+
Na+
