chapter five membranes

Question 1

equilibrium & homeostasis

Answer 1

NOT the same thing

Question 2

plasma membrane

Answer 2

control of material exchanges, mediation of cell environment interactions

Question 3

what does the plasma membrane help us understand?

Answer 3

how things get from inside to outside and outside to inside through the layer (membrane)

Question 4

diffusion

Answer 4

movement of a substance from high substance concentration to low substance concentration due to random thermal molecular motion, NO energy (cannot have energy input)

Question 5

kinetic energy

Answer 5

molecules are moving, absolute zero will get molecules to stop moving, kinetic energy never stops

Question 6

factors affecting diffusion of a substance across a membrane

Answer 6

temperature (directly), molecular weight (inversely), surface area (directly), gradient (directly), membrane permeability (directly), distance (inversely)

Question 7

gradient

Answer 7

difference between stuff inside vs outside the cell, no gradient = no diffusion

Question 8

flux

Answer 8

amount of substance that crosses a defined surface area per unit time (diffusion per time), time matters, matters in how quickly things diffuse

Question 9

diffusion equilibrium

Answer 9

state in which the diffusion fluxes in opposing directions are equal, resulting in a new flux of zero, membrane is a barrier from the inside cell to the outside cell and we need to get things across

Question 10

passive transport

Answer 10

no energy, diffusion directly through membrane (proteins are facilitated)

Question 11

channels

Answer 11

move things, but limited to small things

Question 12

what allows for the close of the channel?

Answer 12

proteins ability to flex (changing shape)

Question 13

open channel (leak channel)

Answer 13

remain open most of the time although can close occasionally for brief periods

Question 14

gated channel

Answer 14

closed most of the time or regulate by the cell, will momentarily open based on gradients & diffusion

Question 15

what are the three types of gated channels?

Answer 15

stimulus-gated (ligand gated), voltage gated, mechanosensitive

Question 16

stimulus-gated (ligand gated)

Answer 16

respond to ligand binding (neurotransmitters, hormones)

Question 17

ligand

Answer 17

anything that binds to a protein and causes a response

Question 18

voltage gated

Answer 18

respond to changes in membrane potential (action potentials) (electrical state of cell)

Question 19

mechanosensitive

Answer 19

respond to physical pressure or distortion (tactile)

Question 20

what kind of bonds to ligands bind in?

Answer 20

weak bonds (hydrogen bonds, ion bonds)

Question 21

carrier-mediated transport

Answer 21

transmembrane, but will never be open to both sides of the membrane at the same time, never create a continuous pathway, can take in slightly larger things than channels

Question 22

glucose carriers

Answer 22

too big to fit through a channel

Question 23

saturation

Answer 23

putting more ligands, which increases gradient, does not change the speed of the protein

Question 24

uniport carriers

Answer 24

only transport one kind of substance (substrate), concentration gradient determines which way it will move

Question 25

cotransporters

Answer 25

move two or more substances

Question 26

symport carriers

Answer 26

move two or more substances in the same direction across a membrane

Question 27

antiport carriers

Answer 27

cotransporters move two or more substances in opposite directions across a membrane

Question 28

having a substance go directly through a membrane, a channel or carrier is possible by what?

Answer 28

diffusion

Question 29

active transport

Answer 29

requires energy

Question 30

primary active transport (pump)

Answer 30

4 types of ion ATPase (requires ATP energy): sodium-potassium pump, calcium pump, hydrogen pump, hydrogen potassium pump

Question 31

sodium-potassium pump

Answer 31

maintains membrane potential (antiport), known as basal metabolism, 3:2 ratio (3 sodium out, 2 potassium in)

Question 32

calcium pump

Answer 32

plasma membrane and organelles (uniport)

Question 33

hydrogen pump

Answer 33

mitochondria and plasma membranes (kidney) (uniport)

Question 34

hydrogen potassium pump

Answer 34

plasma membrane (stomach, responsible for stomach acid) (antiport)

Question 35

secondary active transport

Answer 35

moves things against their gradient (uphill), how body absorbs glucose

Question 36

concentration gradient

Answer 36

small, non-charged & non-polar substances pass between phospholipids (in middle where it is most hydrophobic, urea & gasses wiggle way through membrane)

Question 37

what are most molecules in the body?

Answer 37

lipophobic and/or charged and will not pass readily through the bilayer

Question 38

vesicular transport

Answer 38

not using a pump, but moving a cytoskeleton, can move big things into a cell

Question 39

endocytosis

Answer 39

process of bringing something in

Question 40

what are the two parts of endocytosis?

Answer 40

phagocytosis, pinocytosis

Question 41

phagosytosis

Answer 41

cell eating, bringing the cell in

Question 42

pinocytosis

Answer 42

cell drinking

Question 43

exocytosis

Answer 43

process of going out of the cell

Question 44

osmosis

Answer 44

diffusion of water, movement of water from an area of high water (low solute) concentration to an area of low water (high solute) concentration due to random thermal molecular motion

Question 45

solution =

Answer 45

solute + solvent

Question 46

osmotic pressure

Answer 46

pressure that must be applied to oppose osmosis

Question 47

osmolarity

Answer 47

concentration of a solution expressed as number of solutes per liter (regardless of solute type) (can use to compare anything in the world)

Question 48

a normal cell =

Answer 48

300 mOsm

Question 49

tonicity

Answer 49

describes the volume of change of a cell when placed in a solution

Question 50

what are the two rules of tonicity?

Answer 50

1. always comparing a solution to a normal human cell 2. the solute must be impermeable (solute cannot get across the membrane)

Question 51

crenate

Answer 51

cell shrinks

Question 52

hypertonic

Answer 52

causes cell to break

Question 53

cells don't often get dunked into beakers of solutes so why is osmosis important?

Answer 53

we change the solute concentration of the cell as nutrients come into the body through channels or carriers creating a water gradient so food can be digested

Question 54

what is the first rule of electricity?

Answer 54

opposites attract

Question 55

how is work performed?

Answer 55

when oppositely charged particles come together

Question 56

electrical potential (E)

Answer 56

voltage difference between two points (separation of charges)

Question 57

voltage (V)

Answer 57

measure of potential (separated charge) to do work (units of potential)

Question 58

membrane potential (Vm or Em)

Answer 58

voltage difference between the inside and outside of the cell

Question 59

current (I)

Answer 59

movement of an electrical charge (work is being done)

Question 60

Ohm's Law

Answer 60

I = E/R (electrical potential / resistance)

Question 61

resistance

Answer 61

whether or not the substances will flow through (permeability)

Question 62

does the material conduct? (equation)

Answer 62

g = conductance = 1/R THEN I = gE

Question 63

what is the flow of ions dependent on?

Answer 63

how big the gradient is and is the membrane permeable

Question 64

equilibrium potential (Ex)

Answer 64

the voltage that would exist across a membrane if it were exclusively permeable to one ion in which voltage force is equal and opposite to concentration force

Question 65

what happens if membrane potential and equilibrium potential are the same?

Answer 65

there is no driving force for that ion, they are zero

Question 66

what happens if membrane potential and equilibrium potential are different?

Answer 66

there has to be a driving force to create a flux