cell membrane

Question 1

characteristics of cell membrane

Answer 1

• boundary between inside/outside of cell
• liquid
• only 8nm thick

Question 2

selectively permeable

Answer 2

can “choose” what goes into or out of cell, direct consequence of its structure

Question 3

fluid mosaic model

Answer 3

fluid: proteins and phospholipids can move laterally (switches positions about 10^7 times/sec), kinked tails enhance fluidity

Question 4

definition of a model

Answer 4

hypothesis that is updated as new information is discovered

Question 5

cholesterol

Answer 5

keeps membrane from solidifying (see pic i’m notes). a “fluidity buffer that resists change in membrane fluidity that can be caused by changes in temperature

Question 6

carbohydrates

Answer 6

• used for cell recognition (MHC class 1)
• most = glycoproteins (covalently bonded to proteins)
• some = glycolipids
• examples: A B O blood antigens

Question 7

permeability of bilayer nonpolar molecules

Answer 7

like CO2, N2, O2, hydrophobic and can therefore dissolve in the lipid bilayer (no proteins needed)

Question 8

permeability of bilayer polar molecules

Answer 8

such as water, ions, glucose; hydrophilic and must use a membrane protein

Question 9

membrane proteins

Answer 9

• doesn’t matter if it’s hydrophilic or hydrophobic
• peripheral (in or out not both) or integral (within the membrane)
• used to move materials, communicate, attachment, as enzymes, etc

Question 10

ion channels

Answer 10

specific to each ion, may be gated, diffusion, active transport

Question 11

aquaporin

Answer 11

moves water, osmosis, passive transport

Question 12

carrier proteins

Answer 12

• moves glucose in facilitated diffusion, passive transport

- with ATP can be a pump (Na/K pump), active transport

Question 13

Na/K pump

Answer 13

• carrier protein, moves sodium out of the cell and potassium into the cell
• 3Na+ and 2K- per cycle
• 150 cycles a second, lots of ATP

Question 14

cell charge

Answer 14

because of unequal numbers being pumped in the Na/K pump, the cell takes on a negative charge. also known as a protein gradient

Question 15

active transport

Answer 15

uses cell energy (ATP) to move materials in/out of cell. ALWAYS goes from low to high concentrations (against the concentration gradient)

Question 16

passive transport

Answer 16

• materials move across a cell membrane with/down the concentration gradient with no energy supplied by the cell (kinetic energy).
• diffusion, osmosis, facilitated diffusion

Question 17

diffusion

Answer 17

movement of molecules from high to low concentration without energy from cell until equilibrium is reached

Question 18

conditions that make diffusion faster

Answer 18

higher temperature, larger surface area, higher concentration gradient, smaller particles, medium (solid=slow, liquid=fast, gas=fastest)

Question 19

osmosis

Answer 19

moving water across a cell membrane from high to low concentration until equilibrium is reached, type of diffusion

Question 20

hypotonic solution

Answer 20

low solute

Question 21

hypertonic solution

Answer 21

high solute

Question 22

isotonic solution

Answer 22

equal amounts of solute (doesn’t really exist)

Question 23

cytolysis

Answer 23

when a cell explodes from pressure

Question 24

turgor pressure (turgid)

Answer 24

cell wall keeps cell from exploding by pushing back (normal)

Question 25

shrivel

Answer 25

in a hypertonic solution, an animal cell shrivels

Question 26

plasmolyzed

Answer 26

in a hypertonic solution, a plant cell plasmolyzes

Question 27

flaccid

Answer 27

plant cells starting to wilt in isotonic solution

Question 28

osmoregulation

Answer 28

control of water balance and solute concentrations LOOK UP FISH THING

Question 29

paramecium

Answer 29

pond water, contractile vacuole, ATP

Question 30

what do human cells do?

Answer 30

pump solutes to try to make an isotonic solution - move the solute and the water will flow

Question 31

endocytosis

Answer 31

brings IN substrates, 2 types, ATP

Question 32

pinocytosis

Answer 32

liquids

Question 33

phagocytosis

Answer 33

solids, sometimes old cells; receptor mediated endocytosis

Question 34

exocytosis

Answer 34

exporting large particles out, ATP