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Biology 111 > Chapter 6: plasma member and lipids > Flashcards

Chapter 6: plasma member and lipids Flashcards

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1
Q

what was the defining point in evolution of life?

A

the formation of plasma member

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2
Q

plasma membrane

A

protective barrier for cells that consists of lipids (fats and oils), carbohydrates, and proteins

A LIPID BILAYER IN CELL

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3
Q

why is the plasma membrane important?

A

protect cells interior environment from the influence of the exterior environment

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4
Q

the plasma membrane also acts as a what?

A

fence/gatewat that regulates entry and exit of material in and out of the cell

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5
Q

lipids

A

class of macromolecule that includes fats, oils, and waxes
Do not consist of monomers

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6
Q

why are lipids hydrocarbons

A

consist of a high proportion of C-C and C-H bonds (non polar)

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7
Q

why are hydrocarbons non polar

A

due to the equal negativites that exist between C and H

so it has high pe

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8
Q

are hydrocarbons insoluble or soluble

A

insoluble in water (due to nonpolar nature hence it is hydrophobic) BUTT only soluble in nonpolar solvents

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9
Q

fatty acids

A

simple lipids that have long nonpolar(hydrophobic) hydrocarbon tail bonded to a polar (hydrophilic) carboxyl group

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10
Q

how many carbon atoms does a hydrocarbon chain of a fatty acid have?

A

14-20 carbon atoms

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11
Q

saturated fatty acids

A

bonds formed between carbon atoms consist entirely of single bonds resulting in this

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12
Q

when do unsaturated fatty acids/ polyunsaturated fatty acids result?

A

whens bonds form between carbon atoms of a fatty acid are double bonded

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13
Q

steroids

A

have four ring structure and unique chemical group attached to it

  • these chemical groups distinguish different steroids
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14
Q

what is cholesterol?

A

a steroid made by our livers and obtained from our diets

  • aids with rigidity
  • allows vein to be more flexible
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15
Q

why is cholesterol important?

A

important constituent of cell membranes

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16
Q

what is a precursor molecule for production of testosterone and estrogen?

A

Cholesterol

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17
Q

Fats

A

have a glycerol molecule joined to 3 fatty acids
- have high pe
- a macromolecule with no monomers

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18
Q

are fats a polymer?

A

NO bc they are not made of monomers

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19
Q

how are fats formed?

A

Condensation reaction/dehy./ polymerization between hydroxyl group on glycerol and carboxyl group on fatty acid

  • resulting bond is an ester linkage
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20
Q

glycerol is covalently bound to 3 fatty acids so fats can be called

A

triacylglycerols or triacylglycerides

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21
Q

why do fats have high pe

A

due to # of C-H and C-O bonds in fatty acid tails so it acts as an energy reservoir (like carbs!)

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22
Q

Do carbohydrates or fats have higher potential energy?

A

fats!

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23
Q

are fatty acids linked into chains like amino acids, nucleotides, carbohydrates?

A

no

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24
Q

phospholipids

A

core component of plasma membrane (mesh of lipids)

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25
Q

what are phospholipids made of?

A

glycerol molecule covalently bound to 2 fatty acid (hydrophobic) tails via the ester linkage, along with a phosphate group (hydrophilic)

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26
Q

note that the phosphate group can also…

A

bind to an additional small charged or polar molecule

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27
Q

why are phospholipids unique?

A

bc they are amphipathic

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28
Q

amphipathic

A

both polar and nonpolar regions/properties

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29
Q

why is the phosphate functional group in a phospholipid structure hydrophilic?

A

Due to the negative electric charge

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30
Q

why are the 2 fatty acids in a phospholipid structure hydrophobic?

A

bc they are nonpolar

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31
Q

in water, phospholipids _____ arrange themselves so that their polar/hydrophilic heads face toward water molecules and hydrophobic tails face away from them

A

spontaneously

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32
Q

in water phospholipids are able to turn into either a…

A
  1. micelle
  2. lipid bilayer
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33
Q

micelle

A

spherical aggregate of lipids (single layer of phospholipids)
hydrophilic head interacts w. water and hydrophobic tails interact w. 1 another

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34
Q

lipid bilayer

A

paired sheets of phospholipids (2 layers of phospholipids) that is permeable (must know that it is permeable)

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35
Q

permeability

A

ability of certain substances to pass through it (in and out the cell)

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36
Q

lipid bilayers are highly ____

A

selective (in terms of permeability meaning some substances are able to pass through them easily than others)

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37
Q

what can cross the bilayer easily?

A

Small nonpolar (hydrophobic and soluble in lipids) and polar molecules (H2O and O2)

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38
Q

in the case of charged ions and large polar molecules, it needs ____ to cross the membrances

A

assistance!!
if not it cant cross

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39
Q

charged and polar molecules are what

A

hydrophilic and not rlly soluble in hydrophobic interior of bilayer

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40
Q

lipid structure affects…

A

membrane permeability

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41
Q

length of fatty acid tails and composition of saturated vs unsaturated fatty acids affect

A

permeability

42
Q

bilayers with unsaturated fatty acids produce

A

kinks in the bilayer due to the presence of double bonds

43
Q

what do these kinks do?

A

create space in between hydrophobic tails of the bilayer that increases permeability

44
Q

since bilayers with saturated fatty acids do not have double bonds they produce…

A

more tightly packed membranes, having less space —– decreasing permeability

this is what saturated fatty acids within the bilayers do^

45
Q

hydrocarbon tail length affects _____

A

permeability

46
Q

longer hydrocarbon tail

A

less permeable the membrane

47
Q

shorter hydrocarbon tail

A

more permeable the membrane

48
Q

presence of cholesterol in membrane

A

reduces permeability

49
Q

how does cholesterol orient itself?

A

hydrophilic hydroxyl group faces water and hydrophobic isoprenoid tail embeds in membrane

50
Q

why does cholesterol reduce membrane permeability?

A

fused rings of it rings phospholipid tails closer tg, reducing it

51
Q

membranes have fluidity and movement of that fluid is correlated to

A

temperature

meaning temp. affects permeability

52
Q

higher temp

A

faster lipids move, more permeable
(liquid-like membrane)

53
Q

lower temp

A

slower lipids move, more impermeable or less permeable
(stronger/rigid membrane)

54
Q

diffusion

A

spontaneous movement or spreading of ions and molecules

55
Q

how do molecules move across membrane?

A

by diffusion

56
Q

when do concentration gradients come into play?

A

when theres a difference in the amount / concentration of a solute in one area relative to another

57
Q

when a concentration gradient exist, solutes natural tendency is to

A

move from an area of high concentration to an area of low concentration… diffuse down their concentration gradient

58
Q

when there is no concentration gradient solutes….

A

move randomly in all directions in a solution

59
Q

tonicity

A

ability of a solution surrounding a cell to cause a gain/loss of water

  • cells react to these changes in solute concentrations in their environment
60
Q

changes in tonicity affect…

A

sell structure

61
Q

hypertonic

A

solution surrounding a cell has higher concentration of solutes than the inside of the cell

  • water exits cell and cell shrivels
62
Q

hypotonic

A

solution surrounding a cell has lower concentration of solutes than the inside of the cell

  • more water outside than inside
  • water enters cell and cell swells and burstttt
63
Q

isotonic

A

solution surrounding the cell has an equal concentration of solutes as inside of the cell

  • no net movement of water (cells remain normal)
  • solute in and out of cell
64
Q

cell membranes are a fluid mosaic of….

A

lipids and proteins

65
Q

_____ are another critical component of plasma membranes

A

proteins!!

66
Q

fluid mosaic model

A

current model for the arrangement of molecules in the plasma membrane

membrane is a mosaic of protein + lipid molecules moving in motion

67
Q

since proteins have polar to nonpolar r groups/ side chains, they are

A

amphipathic

68
Q

amphipathic

A

polar (charged) portions proteins face the cell exterior (water) whileeee nonpolar (no charge) face cell interior

69
Q

2 groups of proteins that play important role in stability + function of plasma membrane

A
  1. transmembrane/integral proteins
  2. peripheral proteins
70
Q

transmembrane/integral proteins

A

proteins that embed within lipid bilayer (plasma membrane) bc of their hydrophobic core

ex: ion channels/protein channels and carrier proteins

71
Q

peripheral proteins

A

proteins that lie on inner/ outer surface of lipid bilayer

  • exterior is polar
  • interior is nonpolar
72
Q

channel and carrier proteins regulate…

A

diffusion

73
Q

how are ions able to enter + exit the cell?

A

via ion channels or channel proteins (specialized transmembrane/ integral proteins)

74
Q

due to ion having charge, what exists across membranes??

A

electrical gradients/ voltage (diff. in electrical charge)

75
Q

unequal distribution of ions on each side of membrane causes…

A

cytoplasmic side of membrane to have overall negative charge

extracellular side has overall positive charge

76
Q

2 forces drive diffusion of ions across a membrane

A
  1. chemical force (ions concentration gradient)
  2. electrical force (electrical gradient created by differences in electrical charge across membrane)
77
Q

both forces combined acting on an ion =

A

electrochemical gradient

78
Q

structure of channel (transmembrane/integral proteins) determines

A

specificity of ion/molecule that passes through it
and its selective (in what enters/exits through them)

which is important to keep organism alive and to relieve disfunction

ex: aquaporin allows water to cross plasma membrane but not other molecules/ions
mediated by amino acids in channel that interact w. only water

79
Q

many ion channels are considered

A

voltage-gated ion channels (response to signal/stimulus like electrical stimulus) … open or close allowing molecules to enter cell

80
Q

example of voltage gated ion channels…

A

under normal cellular conditions K+ channels stay closed.

in response to electrical changes across plasma membrane, K+ channels open allowing these ions to passively exit the cell

81
Q

diffusion is ______ bc energy is not requires to push K+ atoms out of cell, these ions are following electrochemical gradient

A

passive
(solute moves from high to low so it doesn’t need energy)

82
Q

carrier proteins

A

regulate diffusion of molecules across membranes through conformational change

BINDSSS to solute on 1 side of membrane, changing the conformation then substrate is released on opposite side of membrane.

  • specialized transmembrane/integral proteins
83
Q

conformational change is to

A

hold a substrate/reactant while binding

84
Q

difference between channel proteins and carrier proteins

A

channel proteins have pores allowing molecules to enter/exit cell

carrier proteins bind to solute on one side of the membrane, changing their conformation resulting release of solute in the opposite side of the membrane due to the conformational change

85
Q

GLUT-1

A

a glucose transporter which is an example of carrier protein

86
Q

depending on glucoses concentration gradient, GLUT-1 can

A

bind to glucose on either side of the membrane.
as a result of a conformation change in its structure, promote the passive transport of glucose across membrane

87
Q

passive diffusion of ions across a plasma membrane with the help of a carrier protein/channel protein is also called

A

facilitated diffusion

88
Q

protein pumps regulate

A

active transport

89
Q

cells also have the ability to move ions/molecules against….

A

concentration gradient so LOW to HIGH AKA ACTIVE TRANSPORT

90
Q

active transport

A

type of transport when substancees are moved against concentration gradient of a membrane, going low to high

requires energy so it is not passive

91
Q

protein pumps

A

proteins that facilitate active transport

ex: Sodium potassium pump

92
Q

sodium-potassium pump uses ________ to exchange Na+ for K+ across the plasma membrane of animal cells

A

ATP Hydrolysis (energy)

93
Q

interior of cell has

A

high concentration of K+ ions and low concentration of Na+ ions

where K+ stays in and Na+ stays out

94
Q

how does the sodium-potassium pump maintain concentration gradient?

A

pumps 3 Na+ ions out of cell and pumps 2 K+ ions into cell
(ions are being transported against their concentration gradient)

95
Q

sodium-potassium pump converts energy from ATP and creates

A

electrochemical gradient across membrane—–creates potential energy for the cell

96
Q

cotransport is coupled transport by a membrane protein

A

coupled meaning 2 diff pumps

97
Q

cell can use the potential energy created by the sodium potassium pump to ..

A

transport additional molecules across plasma membrane (aka cotransport/secondary transport)

98
Q

example of cotransport/secondary transport is the sodium-glucose cotransporter where

A

gut cells use the Na+ gradient created by the sodium-potassium pump to import glucose into cells against its gradient

99
Q

significance of active transport is that

A

ions + molecules can be concentrated/ diluted inside a cell depending on the needs of the cell

100
Q

solutes reach equilibrium when

A

the concentration of solute is constant throughout a system

Biology 111 (10 decks)

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