chapter 7: the membrane

Question 1

cell membrane

Answer 1

boundary of living cell and its surroundings

Question 2

why is the cell membrane important?

Answer 2

allows cells to live
lets nutrients in
lets waste out

Question 3

most abundant molecule in the plasma membrane

Answer 3

phospholipids

Question 4

structure of a phospholipid

Answer 4

hydrophobic head
hydrophilic tail

Question 5

what bonds are in the hydrophobic region of a phospholipid?

Answer 5

nonpolar bonds between C-H in fatty acids

Question 6

what holds phospholipids together in the membrane?

Answer 6

their affinity for water
***not held together by bonds

Question 7

does the fluidity of the membrane affect the membrane’s function?

Answer 7

yes, a less fluid membrane is less effective

Question 8

are phospholipids attached to one another in the membrane

Answer 8

no, basically floating very close to each other

Question 9

how often do phospolipids move laterally in the membrane?

Answer 9

10^7 times per second

Question 10

how often do phospholipids flip-flop in the membrane?

Answer 10

once per month

Question 11

a fluid membrane occurs when

Answer 11

the phospholipids have unsaturated hydrocarbon tails with kinks

Question 12

a viscous membrane occurs when

Answer 12

the phospholipids have saturated hydrocarbon tails with no kinks

Question 13

what affect does increasing temperature have on the membrane?

Answer 13

increases fluidity
decreases viscosity

Question 14

what affect does lowering the temperature have on the membrane?

Answer 14

decreases fluidity
increases viscosity

Question 15

what affect do saturated fatty acids have on the membrane?

Answer 15

linear fatty acids
phospholipids more packed
more viscous
less fluid
good at higher temp

Question 16

what affect do unsaturated fatty acids have on the membrane?

Answer 16

bent fatty acids
phospholipids less packed
less viscous
more fluid
good at lower temp

Question 17

fluidity of the membrane depends on

Answer 17

temperature
saturation of phospholipids fatty acids
cholesterol

Question 18

purpose of cholesterol in the membrane

Answer 18

fluidity buffer

Question 19

what affect does cholesterol have on the membrane at high temps?

Answer 19

decreases fluidity

Question 20

what affect does cholesterol have on the membrane at low temps?

Answer 20

increases fluidity

Question 21

fluid mosaic model depicts

Answer 21

the strcuture of the cell membrane

Question 22

special thing about phospholipids

Answer 22

amphipathic structure

Question 23

ampipathic meaning

Answer 23

contains hydrophobic and hydrophilic regions

Question 24

properties of the fluid mosaic model

Answer 24

membrane is a fluid structure with a mosaic of various proteins embedded and attached to phospholipid bilayer

phospholipid bilayer is the “fluid” part of the membrane
proteins are the “mosaic”

Question 25

glycoprotein

Answer 25

sugar covalently bonded to protein

Question 26

glycolipid

Answer 26

sugar covalently bonded to lipid

Question 27

membrane structure results in

Answer 27

selective permeability

Question 28

what does selective permeability do for the cell?

Answer 28

allows it to regular the cell's molecular traffic by only letting specific molecules through the membrane

Question 29

what molecules can go through the membrane?

Answer 29

nonpolar molecules

Question 30

what molecules cannot go through the membrane?

Answer 30

ions polar molecules

Question 31

diffusion

Answer 31

molecules move to spread out evenly in the available space

Question 32

where will molecules tend to move?

Answer 32

from an area of high concentration to low concentration

Question 33

net diffusion

Answer 33

net movement of particles from an area of high concentration to low concentration

Question 34

equillibrium

Answer 34

equal concentration on both sides of the membrane

Question 35

facilitated diffusion

Answer 35

passive transport across the membrane with the help of a channel or carrier protein

Question 36

passive transport

Answer 36

movement of molecules across the membrane that doesn't require energy

Question 37

active transport

Answer 37

movement of molecules across the membrane that requires energy

Question 38

transport proteins

Answer 38

enable specific ions and polar molecules to cross membrane

Question 39

channel proteins

Answer 39

have a hydrophilic channel that certain molecules use a tunnel

Question 40

aquaporins

Answer 40

channel protein that acts as a passage of water through membrane through facilitated diffusion

Question 41

carrier proteins

Answer 41

hold on to passengers and change shape in a way that shuttles them across

Question 42

solution

Answer 42

liquid that is a homogenous mixture of substances

Question 43

concentrated solution

Answer 43

more solute less water

Question 44

dilute solution

Answer 44

less solute more water

Question 45

osmosis

Answer 45

water moves until solution concentrations on both sides are equal

Question 46

where does water move in a solution?

Answer 46

from an area of low solute concentration to an area of high solute concentration

Question 47

tonicity

Answer 47

ability of a solution to cause water movement

Question 48

hypotonic solution

Answer 48

lower solute concentration

Question 49

isotonic solution

Answer 49

same concentrations of solute on inside and outside

Question 50

hypertonic solution

Answer 50

higher solute concentration

Question 51

animal cell in a hypotonic solution

Answer 51

lysed

Question 52

2 important things about tonicity

Answer 52

comparable (no numbers or units) only describes the solution

Question 53

animal cell in an isotonic solution

Answer 53

normal

Question 54

animal cell in a hypertonic solution

Answer 54

shriveled

Question 55

plant cell in a hypotonic solution

Answer 55

turgid (normal)

Question 56

plant cell in an isotonic solution

Answer 56

flaccid

Question 57

plant cell in a hypertonic solution

Answer 57

plasmolyzed

Question 58

ATP is energy that

Answer 58

cells use

Question 59

what type of proteins are active transport pumps?

Answer 59

carrier

Question 60

active transport

Answer 60

requires energy to move some molecules across the cell membrane

Question 61

how does the sodium potassium pump work

Answer 61

3 Na+ attach to pump from inside the cell P from ATP uses energy to push Na+ outside of the cell, pump changes shape 2 K+ attach to pump from outside of cell inorganic phosphate is released, pump changes shape K+ is released inside the cell

Question 62

ATP hydrolysis reaction

Answer 62

ATP --> Pi + ADP

Question 63

sodium potassium pump exchange

Answer 63

3 Na+ out of cell 2 K+ in to cell

Question 64

exocytosis

Answer 64

large molecules leave the cell

Question 65

secretion

Answer 65

cell secretes by fusion of vesicles with the plasma membrane

Question 66

are proteins large?

Answer 66

yes

Question 67

endocytosis

Answer 67

cell takes in molecules by forming new membrane vesicles from the plasma membrane

Question 68

types of endocytosis

Answer 68

phagocytosis pinocytosis receptor mediated

Question 69

ligand

Answer 69

any molecule that binds specifically to a receptor site of another molecule

Question 70

phagocytosis

Answer 70

cell engulfs large particles

Question 71

pinocytosis

Answer 71

cell engulfs fluid

Question 72

receptor mediated endocytosis

Answer 72

specific molecules are ingested into the cell through a receptor-ligand interaction