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BIOL 231 > Week 2 > Flashcards

Week 2 Flashcards

1
Q

endomembrane system components consists of a network of internal membranes made up of ___

A

lipid bilayers

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2
Q

endomembrane system components:

include what structures?

A

endoplasmic reticulum (ER)
- smooth (SER) –> no ribosomes
- rough (RER) –> has ribosomes on its surface

Golgi complex

vesicles

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3
Q

describe endoplasmic reticulum structure:

network of ___

wall of tubules composed of a ___

the space inside the tubes is called the ___

the smooth and rough ER are…

A

network of interconnected tubules

wall of tubules composed of a lipid bilayer

the space inside the tubes is called the lumen

the smooth and rough ER are interconnected with each other and the outer bilayer of the nuclear envelope

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4
Q

specialized functions of the SER:

site of ___

site of ___

site of ___

A

lipid synthesis

cholesterol and steroid synthesis

fatty acid desaturation

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5
Q

specialized functions of the RER:

site for ___

these ___ are used for…

A

synthesis of proteins bound for export from the cell, or for use in the endomembrane system

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6
Q

structure of Golgi apparatus:

series of ___

wall of tubes are a ___

cis face:

trans face:

A

flattened tubes (sacs)

lipid bilayer

cis face: receives transport vesicles from ER

trans face: sends secretory vesicles away from the Golgi

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7
Q

3 function of Golgi apparatus:

A

(1) proteins and other molecules may be modified

(2) molecules are sorted by eventual destination

(3) molecules are released in vesicles

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8
Q

describe the Rough ER

A

has ribosomes on its surface, primarily manufactures proteins

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9
Q

describe the smooth ER

A

no ribosomes, manufactures other macromolecules

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10
Q

describe vesicles

A

transport of molecules to and from the Golgi Complex

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11
Q

describe the Golgi complex

A

modifies, sorts, packages, and distributes macromolecules

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12
Q

journey through the endomembrane network

A

(1) proteins made in the RER

(2) transport vesicle: contains products

(3) Golgi apparatus –> chemical modifications

(4) secretory vesicles

(5) exocytosis

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13
Q

exocytosis (definition)

A

process by which material is exported out of the cell

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14
Q

a ___ fuses with the plasma membrane to release its contents out of the cell

example:

A

secretory vesicle

ex. insulin secretion

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15
Q

material can enter the cell by ___

A

endocytosis

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16
Q

the plasma membrane surrounds contents from outside the cell, trapping it in an ___

A

endocytic vesicle

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17
Q

the ___ surrounds contents from outside the cell, trapping it in an endocytic vesicle

A

plasma membrane

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18
Q

endocytosis can be a ___ process (using receptors), or ___ (taking up of water and nutrients)

A

specific == using receptors

passive == taking up water and nutrients

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19
Q

endocytosis can be a specific process (___), or passive (___)

A

specific == using receptors

passive == taking up water and nutrients

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20
Q

the endocytic vesicle will then fuse with another type of vesicle, a ___

A

lysosome

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21
Q

lysosomes are…

A

specialized vesicles that digest:
- material from outside the cell
- or material from inside the cell (“worn out” organelles)

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22
Q

primary lysosome (comes from the Golgi) contains ___

A

digestive enzymes

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23
Q

lysosomes fuse with ___ or other cellular organelles, to form a ___

A

endocytic vesicles

secondary lysosome

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24
Q

tuberculosis bacterium:

TB kills about ___ annually

A

2 million

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25
Q

TB bacteria are able to prevent…

Thus…

A

phagosome/lysosome fusion

thus, TB survives and has a place to live in the cell

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26
Q

TB bacteria multiples…

___ and ___ it

spreads to…

A

multiplies inside the macrophage

kills and devours it

spreads to infect more cells

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27
Q

mitochondria:

describe structure of:

membrane

outer membrane

inner membrane

center

A

double lipid bilayer

outer membrane covers entire organelle

inner membrane is extensively infolded
- folds are called cristae

liquid center –> the matrix

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28
Q

what is the endosymbiotic theory?

A

mitochondria only arise from pre-existing mitochondria –> reproductive themselves

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29
Q

what is function of mitochondria?

A

energy metabolism –> ATP production

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30
Q

chloroplast (structure)

membrane

center

A

double lipid bilayer

outer and inner envelope membranes cover the entire organelle

inside center:
- internal membranes organized into stacked disks
- thylakoid – single disk
- granum – stack of thylakoids
- stroma – soluble material around grana

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31
Q

chloroplast (function)

A

site of photosynthesis in plant cells

light energy is converted into usable chemical energy

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32
Q

cytoskeleton:

cells need ___

A

internal structural support

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33
Q

the cytoskeleton is made up of…

some ___ are purely for…

some ___ play a role in…

some ___ help…

A

multiple types of protein fibers

  • structural support
  • transport within the cell
  • help the cell move
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34
Q

extracellular matrix is made of…

A

secreted molecules from cells

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35
Q

3 functions of extracellular matrix:

A

(1) hold cells together in tissues (glue)

(2) strengthens and cushions tissues like cartilage and bone

(3) can filter material b/n cells (ex. kidneys)

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36
Q

where is the extracellular matrix and cytoskeleton located in the cell?

A

extracellular matrix – outside cell

cytoskeleton – inside cell

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37
Q

what is the extracellular matrix made of?

A

extracellular fluid

collagen

fibronectin

proteoglycans

integrins (in the plasma membrane)

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38
Q

what is the cytoskeleton made of?

A

microfilaments

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39
Q

plasma membrane defines…

it’s a ___

A

defines the inside and outside of a cell

it’s a barrier

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40
Q

PMs are ___ barriers because they regulate…

A

selective barriers

regulate transport into/out of cells

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41
Q

the PM is ___ and cells can adjust…

A

the PM is dynamic and cells can adjust
- the chemistry of the PM
- the molecules that associate with it

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42
Q

who discovered that the plasma membrane is a phospholipid bilayer?

what did he use?

A

evert gorter

red blood cells

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43
Q

why did evert porter use RBCs to study the phospholipid membrane?

A

(1) easy to obtain

(2) easy to count

(3) are of uniform size

44
Q

what was the result of evert gorter’s experiments?

A

surface area (SA) of the monolayer is double the surface area of the cells (2:1) ratio

cell membranes are a phospholipid bilayer

45
Q

what would the ratio have been if he had used nuclear envelope membranes?

A

4:1 ratio

nucleus has a double bilayer membrane

46
Q

plasma membranes are ___ than just a phospholipid bilayer

A

much more

47
Q

other parts of the plasma membrane:

A

polysaccharides

peripheral proteins

integral (transmembrane) proteins

cholesterol

48
Q

what is the fluid mosaic model of membranes?

A

PMs are fluid structures

phospholipid bilayer is like a “lake”. Molecules are “floating” around in it

49
Q

how did we come up with the fluid mosaic model of membranes?

what did this experiment entail? and show?

A

cell fusion experiment – mix a mouse cell (green membrane proteins) with human cell (red membrane proteins)

over time, the hybrid cells show increasingly intermixed proteins

proteins are laterally diffusing around the membrane –> the membrane is fluid

50
Q

what is the other experiment that shows the cell membrane is fluid?

what did this experiment show?

A

photo-bleaching experiments

label membrane proteins with a fluorescent dye –> bleach and area of the cell surface with a laser –> slowly, the bleached spot disappears because other dyed membrane proteins flow into the area –> demonstrates the cell membrane is fluid

51
Q

why is it important to maintain fluidity level?

A

if too fluid –> will not serve as a boundary and will fall apart

if too solid –> will not permit integral proteins to flex (change shape) and carry out their functions
- ex. integral transport or signaling proteins

52
Q

how do cells regulate membrane fluidity by changing ___ in ___ ways

A

changing fatty acid chains of phospholipids

2 ways

53
Q

what are the 2 ways cells change membrane fluidity by changing fatty acid chains of phospholipids?

A

change % of phospholipids with saturated/unsaturated FA chains

change % of phospholipids with long or short FA chains

54
Q

how do cells change % phospholipids with saturated/unsaturated FA chains?

A

higher concentration of phospholipids w/ unsaturated FAs –> pack less tightly == more fluid

higher concentration of phospholipids w/ saturated FAs –> pack more tightly == less fluid

55
Q

how do cells change % of phospholipids with long or short FA chains?

A

higher concentration of phospholipids w/ short FAs –> pack less tightly == more fluid

higher concentration of phospholipids w/ long FAs –> pack more tightly == less fluid

56
Q

changes in ___ affect membrane fluidity and cells need to respond

A

external temperature

57
Q

cells are at a lower temp –> how does PM change?

A

cold temp makes PM less fluid

PM needs to become more fluid == pack less tightly

make phospholipids with FA chains that are:
- shorter
- more unsaturated

58
Q

cells are at a higher temp –> how does the PM change?

A

warm temp makes PM more fluid

PM needs to become less fluid == pack more tightly

make phospholipids with FA chains that are:
- longer
- more saturated

59
Q

a major barrier for molecules crossing a plasma membrane is the ___

A

hydrophobic interior

60
Q

why is the hydrophobic interior a major barrier for molecules crossing a plasma membrane?

A

permeable to non polar molecules

less permeable to small polar molecules

no permeability for larger polar molecules or ions

61
Q

what are the types of membrane transport?

A

diffusion

active transport (anti-diffusion)

62
Q

what is diffusion?

A

the movement of molecules across the membrane from high concentration to low concentration

does not require use of cellular energy

63
Q

what is active transport (anti-diffusion)?

A

movement of molecules across the membrane from low concentration to high concentration

requires use of cellular energy

64
Q

what is necessary for simple diffusion to occur?

A

1) PM must be permeable to particular molecule

2) must be a different in [ ] of that molecule across the membrane

65
Q

the diffusion of molecules that can cross the membrane on their own must be ___

A

facilitated

66
Q

FD is carried out by ___, including ___ and ___

A

transmembrane proteins

channel proteins

carrier proteins

67
Q

transmembrane proteins are ___ and…

A

selective

only transport certain molecules

68
Q

facilitated diffusion is movement driven by diffusion. Is energy required?

A

no

69
Q

cells can regulate FD by regulating:

A

presence or absence of specific carrier or channel proteins

regulating the function of specific carrier or channels

70
Q

how are channel proteins and carrier proteins different?

A

channel proteins:
- like tunnels
- don’t bind to the molecules they transport
- can be always open or gated (opened or closed)
- direction of movement depends on concentration
- movement does not require energy input

carrier proteins:
- must bind to the molecules that they transport
- direction of movement depends on concentration
- movement does not require cellular energy input
- 3 basic types of carrier proteins

71
Q

what are the 3 basic types of carrier proteins and what do they do?

A

uniporters –> transport a single type of molecular species

symporters –> transport 2 molecular species in the same direction, at the same time

antiporters –> transport 2 molecular species in opposite directions, at the same time

72
Q

how can we distinguish b/n carriers and channels?

A

by looking at their kinetics (rates) of transport

channels show linear kinetics

carriers show saturation kinetics

73
Q

channels show ___ kinetics

A

linear

74
Q

carriers show ___ kinetics

A

saturation

75
Q

active transport (anti-diffusion) is used by cells to…

A

build up a concentration gradient of a molecule across a plasma membrane

76
Q

in active transport, moving molecules against a concentration gradient requires ___ and requires ___

A

carrier proteins

energy (usually ATP)

77
Q

in active transport, concentration gradients are critical for some ___

A

biological processes (cellular respiration)

78
Q

what are the 2 ways solutes can be transported across plasma membranes?

A

diffusion

active transport

79
Q

what are the 2 types of diffusion and what do they do/require?

A

simple and facilitated –> neither require energy

simple:
- no proteins required
- no energy input

facilitated:
- channel or carrier
- movement driven by diffusion
- no energy input

80
Q

what does active transport require?

A

carrier

energy input

81
Q

what is a selective (semi-permeable) barrier?

A

a barrier that allows water molecules to pass through, but not most of the molecules dissolved in the water

ex. plasma membrane

82
Q

___ is a measure of the concentration of solutes dissolved in water

A

solute potential (Psi s)

83
Q

pure water has no solutes: it’s psi s = ___ and what is the significance of its value?

A

psi s = 0

highest value

84
Q

water molecules are most concentrated at psi s = ___

A

0

85
Q

adding solutes ___ psi s

psi s…

A

lowers

psi s < 0

negative value

86
Q

as solute concentration increases, water concentration ___, psi s ___

A

decreases

decreases

87
Q

as solute concentration ___, water concentration decreases, psi s ___

A

increases

decreases

88
Q

water moves from areas of ___ psi s to areas of ___ psi s

A

higher psi s to lower psi s

89
Q

if the psi s inside and outside of cell are equal…

A

water is entering and leaving the cell in equal amounts

90
Q

if psi s is higher outside of a cell than inside:

A

greater water concentration outside the cell

cell is hypertonic
solution is hypotonic

water will rush into the cell

cell will swell

cell could burst

91
Q

if psi s is higher inside of a cell than outside:

A

greater water concentration inside of cell

cell is hypotonic
solution is hypertonic

water will rush out of cell

cell will shrink, could dehydrate and die

92
Q

brain capillaries are…

A

fine blood vessels that feed brain tissue

93
Q

molecules must exit a brain capillary by moving…

molecules cannot pass…

this strict control is known as the ___

A

through the plasma membrane of a capillary wall cell

b/n the cells thru the intercellular junction

blood-brain barrier

94
Q

can medicines enter the brain easily?

A

no; because blood brain barrier keeps most medicines from entering the brain

95
Q

how to breach the blood-brain barrier?

A

lower the psi s of blood (inject a solute)

water moves out of capillary wall cells

capillary wall cells shrink slightly and create an opening b/n cells

medicine can pass into the brain

96
Q

Wwhat does mannitol do?

A

lowers the psi s of blood

water moves out of capillary wall cells into the blood

capillary wall cells shrink slightly and create an opening b/n cells

medicine can pass into the brain

97
Q

first law of thermodynamics is also known as the…

it states that…

A

conservation law

energy cannot be created or destroyed

energy can only change from one form of energy to another

total amount of energy in the universe remains constant

98
Q

2nd law of thermodynamics states…

A

no energy transfer is 100% efficient

some energy is always lost to universe and becomes unusable

99
Q

entropy is…

it is continuously ___ in the universe

A

unusable energy

it is continuously increasing

100
Q

usable energy (free energy) in the universe is ___

A

continuously decreasing

101
Q

free energy is known by the letter

A

G

102
Q

what is the formula for free energy (G)?

A

G = H - TS

G = energy available to do work

H = enthalpy (energy in a molecule’s chemical bonds)

TS = amount of disorder in a molecule

T = absolute temperature

S = entropy, unavailable energy

103
Q

-(delta) G:

___ reaction

which has more free energy, products or reactants?

spontaneous or non-spontaneous?

A

exergonic

reactants have more free energy than products

spontaneous

104
Q

+(delta) G:

___ reaction

which has more free energy, products or reactants?

spontaneous or non-spontaneous?

A

endergonic

products have more free energy than reactants

non-spontaneous

105
Q

free energy is referred to as ‘G’ = the energy…

A

the energy in the chemical bonds of a molecule that’s available to do work

106
Q

describe reaction coupling

A

energy to drive endergonic reactions comes from exergonic reactions

107
Q

ATP hydrolysis is endergonic/exergonic

A

exergonic –> the energy is used to power many endergonic reactions

ATP + H2O –> ADP

BIOL 231 (23 decks)

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