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Cellular Biology > Exam Two > Flashcards

Exam Two Flashcards

1
Q

Gorder & Grendell experiment found

A
  • Membranes extracted from RBC’s
    Calculated:
    1) Surface area of RBC’s
    2) surface area of floated lipids
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2
Q

What can be used to see the plasma membrane?

A

Electron microscopy (5 to 10nm thick)

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3
Q

What does the fluid mosaic model allow us to understand?

A

The plasma membrane is NOT a rigid structure
- lipids are free to diffuse within the plasma membrane
-membrane proteins penetrate the lipid bilayer
-membrane proteins can diffuse within the bilayer

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4
Q

What are the biological membranes made of?

A
  • lipids
  • carbohydrates
  • proteins
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5
Q

What does membrane function allow biological membranes to do?

A

preform numerous functions

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6
Q

membranes spontaneously form ________ ?

A

continuous bilayers

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7
Q

What are the two leaflets of the lipid bilayer called?

A
  1. exoplasmic leaflet
  2. cytosolic leaflet
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8
Q

The membrane has to be _______ in order to work.

A

fluid

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9
Q

how do lipids move in the bilayer

A
  • flexion and rotation is extremely fast
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10
Q

lipids can also move through _________ in the bilayer

A

lateral diffusion (also fast)

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11
Q

flip flop (transverse diffusion) is very _____ and ______.

A

rare and slow

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12
Q

cis bonds create _______ in the fatty acid tail

A

kinks

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13
Q

kinks within a fatty acid creates ________

A

less ordered packaging

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14
Q

more cis bonds means more

A

fluid

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15
Q

most membranes lipids have _____ cis double bond

A

one

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16
Q

Why is membrane fluidity important?

A

It allows integral proteins to diffuse within the membrane.

Allows for formation of the membrane sub-structures

Allows for endocytosis and exocytosis

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17
Q

______ maintain membrane fluidity.

A

cells

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18
Q

when temperature drops cells use

A

desaturates

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19
Q

______ bonds are converted to ______ bonds in the fatty acid

A

single; double

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20
Q

Where does lipid synthesis occur?

A

the endoplasmic reticulum (ER)

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21
Q

What is the job of the Golgi apparatus

A

helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell.

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22
Q

scramblase is a protein that randomly ________ lipids to the other ________

A

flips; face

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23
Q

what are the job of flippases?

A

catalyze ATP to move lipids across membrane

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24
Q

glycolipids are ALWAYS ON ____________

A

exoplasmic leaflet

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25
Q

cholesterol is on _______ leaflets

A

both

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26
Q

PS and PI is on ________ leaflet

A

cytosolic

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27
Q

PI Is important for

A

signaling

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28
Q

_________ is common in animal cells; absent in plant cells

A

cholesterol

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29
Q

How does cholesterol act at high temperatures?

A

-prevents phospholipids from spreading out
-prevents breakdown of plasma membrane

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30
Q

How does cholesterol act at low temperatures?

A

-prevents close packing of phospholipid fatty acid tails
-prevents freezing

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31
Q

Types of membrane proteins

A

integral proteins and peripheral proteins

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32
Q

intergral proteins contain……

A

lipid anchored proteins

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33
Q

types of integral mem. proteins

A

transmembrane, monolayer associated, lipid linked

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34
Q

types of peripheral mem. proteins

A

protein attached aka spectrum

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35
Q

How do membrane proteins cross the membrane?

A

As an alpha helix

36
Q

what is an example of a membrane proteins thats a beta barrel

A

porins (allow water to quickly enter and leave cell)

37
Q

How do RBC’s become “ghosts”

A

adding water

38
Q

spectrin helps to form….

A

the cortex

39
Q

how is spectrin anchored to plasma membrane

A

by attachment proteins

40
Q

why are membrane domains important?

A
  • cells can restrict movement of membrane proteins
  • can tether membrane proteins to intra/extracellular proteins
  • can tether to membrane proteins of other cell
  • can restrict movement with diffusion barriers
41
Q

On the extracellular side membrane proteins are usually __________.

A

glycosylated

42
Q

What is the glycocalyx?

A

thin layer of sugar coating that protects cells

43
Q

What are lectins?

A

proteins that bind to sugar

44
Q

Why are lectins important

A

they allow WBCs to bind to blood vessel walls near infections

45
Q

What are the two contrasting roles of the plasma membrane

A
  1. prevents solutes from leaving cytoplasm
  2. allows some molecules to transit across the membrane
46
Q

Why do molecules need to be transported across membrane?

A
  • allows for exchange of nutrients and waste
  • allows electrical charges to cross membrane
47
Q

membranes are ________

A

semi-permeable

48
Q

what type of molecule can get through the membrane

A

small non polar

49
Q

what types of molecules CANNOT cross the membrane

A

polar, charged

50
Q

diffusion is when….

A

molecules move from high to low concentration

51
Q

diffusion will only occur if a substance is:

A
  • at diff concentrations across membrane
  • permeable to the membrane
52
Q

rate of diffusion depends on

A
  • difference in concentration across membrane
  • permeability of the membrane
  • SA of the membrane
  • charge of molecule
53
Q

water moving from low solute concentration to high solute concentration is called

A

osmosis

54
Q

how to remember osmosis

A

water follows salt

55
Q

Osmosis occurs in cells when 2 conditions are met

A
  • a concentration difference of solute across membrane
  • impermeability of the plasma membrane to that solute
56
Q

tonicity is the …….

A

measure of osmotic pressure gradient

57
Q

what happens to a cell when its in a hypotonic solution

A

the cell swells due to water entering cell

58
Q

what happens to a cell when its in a hypertonic solution

A

the cell shrivels due to water leaving the cell

59
Q

what happens to a cell when its in an isotonic solution

A

cell volume remains unchanged. no net loss or gain

60
Q

what happens when osmosis occurs in a plant cell

A

turgor pressure

61
Q

what happens when osmosis happens in a plant cell thats in a hypertonic solution?

A

water leaves the cell causing it to shrivel, this is called PLASMOLYSIS

62
Q

osmosis in cells is facilitated by

A

the presence of aquaporin channels. The more aquaporins the determines the rate of osmosis

63
Q

K+ (Postassium) is located where

A

cytosol

64
Q

Na+ (Sodium) is located where

A

extracellular space

65
Q

Ca+2 (calcium) is located where

A

extracellular space

66
Q

Cl- (Chlorine) is located where

A

extracellular space

67
Q

what is resting membrane potential?

A

difference in ion concentration leads to voltage across membran e

68
Q

Electrochemical gradients are only used for

A

CHARGED IONS

69
Q

passive transport is the movement _________

A

down the concentration gradient

70
Q

active transport is the movement _________-

A

up the concentration gradient

71
Q

active transport is only accomplished by

A

transporters

72
Q

passive transport using transporters is also called _________; moves solutes _____ concentration gradient

A

facilitated diffusion; down

73
Q

active transport needs

A

source of energy to pump solute

74
Q

examples of gradient driven pumps

A

symport and antiport

75
Q

The Na+/Glucose Symporter is a steep gradient of _____ used to move

A

Na+, used to move glucose UP its concentration gradient

76
Q

Why are ion channels selective?

A

to ensure only the right ions pass through

77
Q

What does it mean if ion channels are gated?

A

they are open or close

78
Q

What are the major features of the neuron?

A
  • Dendrites
  • Axon
  • Body (Soma)
79
Q

Neurons are able to become _________ which allow them to alter ______ ________.

A

stimulated, membrane potential

80
Q

the stronger the stimulus the stronger the ___________

A

depolarization

81
Q

threshold where a large increase in membrane potential occurs

A

action potential

82
Q

What are the two types of voltage gated ion channels

A
  1. Na+ voltage gated ion channel
  2. K+ voltage gated ion channel
83
Q

Which ion channel moves “slow”

A

K+ voltage gated ion channel

84
Q

Where are voltage gated ion channels found

A

In the axon

85
Q

what happens when action potential reaches synapse

A

synaptic vesicles fuse together

Cellular Biology (4 decks)

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