Cell Membrane

Question 1

how permeable is the cell membrane?

Answer 1

semi/selectively permeable
allows some things in and some things out of the cell

Question 2

how are the heads and tails in the cell membrane? what is this called?

Answer 2

hydrophobic tails
hydrophilic heads
amphipathic

Question 3

what is the early model of the cell membrane?

Answer 3

sandwich membrane:
protein
hydrophilic zone
hydrophobic zone
hydrophilic zone

Question 4

what is the current and accurate cell membrane model?

Answer 4

fluid mosaic model
not rigid
hydrophilic region of protein
phospholipid bilayer
hydrophobic region of protein

Question 5

what components of the cell membrane are in a mosaic pattern?

Answer 5

proteins float randomly in the PLBL

Question 6

what does the fluid property of the cell membrane allow for?

Answer 6

allows the phospholipid to move easily in a lateral direction
the phospholipids can also sometimes flipflop across the membrane

Question 7

what gives the cell membrane more fluidity?

Answer 7

the unsaturated/polyunsaturated hydrocarbon tails that have double bonds

Question 8

what do the saturated hydrocarbon tails do to the cell membrane?

Answer 8

make it more rigid

Question 9

at room temp, what does adding cholesterol to the cell membrane to it?

Answer 9

lowers fluidity, more rigid

Question 10

what happens if you add cholesterol to the cell membrane at low temp?

Answer 10

increases fluidity, prevents phospholipids from clumping

Question 11

what does the versatility of cholesterol at diff temp allow? ex?

Answer 11

allows animals that live in very cold climates to still maintain plasma membrane function
hooves of animals have a lot of cholesterol to prevent freezing when exposed to snow

Question 12

components of the cell membrane (10)

Answer 12

1. ECM/Glycocalyx
2. Integral Protein: Transport Protein
3. Integral Protein: Integrin Protein
4. Integral Protein: Aquaporin
5. Cholesterol
6. Peripheral Protein
7. Cytoplasm and Cytosol
8. Phospholipids
9. Glycoprotein
10. Glycolipid

Question 13

where are integral proteins located?

Answer 13

span across the phospholipid bilayer

Question 14

structure of integral proteins

Answer 14

alpha helixes (secondary structure)

Question 15

what do transport proteins do?

Answer 15

allow specific molecules to enter or exit the cell

Question 16

what do integrins do?

Answer 16

used for cell communication

Question 17

where are peripheral proteins found?

Answer 17

usually found on the inside ofthe cell membrane

Question 18

peripheral protein function

Answer 18

give strength to cell

Question 19

what bring the selectively permeable nature to the membrane?

Answer 19

hydrophobic/nonpolar tails

Question 20

what molecules would not be able to get pass the nonpolar tails?

Answer 20

ionic/charged molecules, most polar molecules, large molecules

Question 21

what molecules would easily get past the nonpolar tails?

Answer 21

nonpolar, small, gases, steroids

Question 22

what will the molecules that cannot get past the cell membrane use?

Answer 22

use specific transport proteins that have a charged interior

Question 23

what does water use to enter and exit the cell membrane?

Answer 23

transport protein called aquaporin

Question 24

what is diffusion?

Answer 24

tendency for molecules to spread out in an open space
diffuse from a high to low concentration
spontaneous and require no ATP
passive transport

Question 25

what is osmosis?

Answer 25

passive transport of water from high to low concentration across a semi permeable membrane

Question 26

hypertonic solutions

Answer 26

high concentration of solutes in solution

Question 27

hypotonic solution

Answer 27

low concentration of solutes in solution

Question 28

isotonic solution

Answer 28

same concentration of solutes on both sides

Question 29

what way does water always move? what if it's isotonic?

Answer 29

hypotonic to hypertonic water still continues to move between the two solutions at equal rate

Question 30

if an animal cell is placed in a hypotonic solution, the cell will?

Answer 30

lyse

Question 31

if an animal cell is placed in an isotonic solution, the cell will?

Answer 31

stable

Question 32

if an animal cell is placed in a hypertonic solution, the cell will?

Answer 32

shrivel

Question 33

if a plant cell is placed in a hypotonic solution, the cell will?

Answer 33

turgid/ rigid

Question 34

if a plant cell is placed in an isotonic solution, the cell will?

Answer 34

flaccid (limp)

Question 35

if a plant cell is placed in a hypertonic solution, the cell will?

Answer 35

plasmolysis - cell membrane pulls away from cell wall

Question 36

which solution do terrestrial animal cells want?

Answer 36

isotonic

Question 37

which solution do terrestrial plant cells wanr?

Answer 37

hypotonic

Question 38

many terrestrial animal cells are in what type of solution?

Answer 38

isotonic

Question 39

what type of solution are protists in?

Answer 39

hypotonic environments and must osmoregulate

Question 40

what is osmoregulation? how do protists do it?

Answer 40

control their water by balance with the help of contractile vacuoles

Question 41

why do plant cells respond differently than animal cells in a solution?

Answer 41

cell wall

Question 42

what is facilitated diffusion?

Answer 42

passive transport of a substance across the cell membrane from a high to low concentration, but requires a transport protein

Question 43

what is active transport?

Answer 43

require ATP as it goes from low to high concentration uphill reaction that goes against the concentration gradient

Question 44

good example of active transport?

Answer 44

Na-K

Question 45

how many and in which direction are the sodiums and postassiums going?

Answer 45

3 Na+ out, 2 K+ in

Question 46

what is a membrane potential/electrochemical gradient?

Answer 46

idea that all cells have voltage on each side of the plasma membrane

Question 47

charge of inside of cell? outside

Answer 47

inside - negative outside - posotive

Question 48

what does the differing charges of the cell interior and exterior do?

Answer 48

favors cations to come into a cell and anions to exit the cell

Question 49

what are animals main pump? plants?

Answer 49

animal - Na-K pump plant - proton pump

Question 50

what do proton pumps do?

Answer 50

actively pump H+ ions out of cells from a low to high concentration

Question 51

potential energy from what can be used to transport other substances across the membrane?

Answer 51

energy generated by transmembrane solute gradients can be harvested by the cell a substance that is actively transported across a membrane can do work as it diffused back by facilitated diffusion

Question 52

what is cotransport ex?

Answer 52

a plant cell actively pumps H+ out of a cell H+ then leaks back into cell passively by facilitated diffusion through a transport protein brings back with it small sugars, amino acids, or nutrients

Question 53

how do large molecules enter or exit a cell? is this active or passive transport?

Answer 53

endo/exocytosis; active

Question 54

large molecule entering cell

Answer 54

endocytosis

Question 55

large molecule existing cell

Answer 55

exocytosis

Question 56

cell takes in food

Answer 56

phagocytosis

Question 57

cell takes in fluid

Answer 57

pinocytosis

Question 58

receptor-mediated endocytosis

Answer 58

very specific proteins on the outside of a cell bind to a specific molecule

Question 59

general term for any molecule (usually small) that binds to something (other a receptor)

Answer 59

ligand

Question 60

what does receptor- mediated endocytosis allow?

Answer 60

allows a cell to take in more substances that in normally would, even if the substance in is low concentrations outside the cell

Question 61

ex of receptor-mediated endocytosis

Answer 61

cholesterol is acquired by cells this way

Question 62

how can transport proteins respond to change in the extracellular environment? ex

Answer 62

with active transport if a cell has enough Na+, a transport protein can slow/shut down the active pumping of the molecule up the concentration gradient

Question 63

what does not depend on if the cell has enough of a substance unlike transport proteins?

Answer 63

diffusion passive transport