Cellular Biology > Exam Two > Flashcards

Exam Two Flashcards

(85 cards)

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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
cholesterol is on _______ leaflets
both
26
PS and PI is on ________ leaflet
cytosolic
27
PI Is important for
signaling
28
_________ is common in animal cells; absent in plant cells
cholesterol
29
How does cholesterol act at high temperatures?
-prevents phospholipids from spreading out -prevents breakdown of plasma membrane
30
How does cholesterol act at low temperatures?
-prevents close packing of phospholipid fatty acid tails -prevents freezing
31
Types of membrane proteins
integral proteins and peripheral proteins
32
intergral proteins contain......
lipid anchored proteins
33
types of integral mem. proteins
transmembrane, monolayer associated, lipid linked
34
types of peripheral mem. proteins
protein attached aka spectrum
35
How do membrane proteins cross the membrane?
As an alpha helix
36
what is an example of a membrane proteins thats a beta barrel
porins (allow water to quickly enter and leave cell)
37
How do RBC's become "ghosts"
adding water
38
spectrin helps to form....
the cortex
39
how is spectrin anchored to plasma membrane
by attachment proteins
40
why are membrane domains important?
- 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
On the extracellular side membrane proteins are usually __________.
glycosylated
42
What is the glycocalyx?
thin layer of sugar coating that protects cells
43
What are lectins?
proteins that bind to sugar
44
Why are lectins important
they allow WBCs to bind to blood vessel walls near infections
45
What are the two contrasting roles of the plasma membrane
1. prevents solutes from leaving cytoplasm 2. allows some molecules to transit across the membrane
46
Why do molecules need to be transported across membrane?
- allows for exchange of nutrients and waste - allows electrical charges to cross membrane
47
membranes are ________
semi-permeable
48
what type of molecule can get through the membrane
small non polar
49
what types of molecules CANNOT cross the membrane
polar, charged
50
diffusion is when....
molecules move from high to low concentration
51
diffusion will only occur if a substance is:
- at diff concentrations across membrane - permeable to the membrane
52
rate of diffusion depends on
- difference in concentration across membrane - permeability of the membrane - SA of the membrane - charge of molecule
53
water moving from low solute concentration to high solute concentration is called
osmosis
54
how to remember osmosis
water follows salt
55
Osmosis occurs in cells when 2 conditions are met
- a concentration difference of solute across membrane - impermeability of the plasma membrane to that solute
56
tonicity is the .......
measure of osmotic pressure gradient
57
what happens to a cell when its in a hypotonic solution
the cell swells due to water entering cell
58
what happens to a cell when its in a hypertonic solution
the cell shrivels due to water leaving the cell
59
what happens to a cell when its in an isotonic solution
cell volume remains unchanged. no net loss or gain
60
what happens when osmosis occurs in a plant cell
turgor pressure
61
what happens when osmosis happens in a plant cell thats in a hypertonic solution?
water leaves the cell causing it to shrivel, this is called PLASMOLYSIS
62
osmosis in cells is facilitated by
the presence of aquaporin channels. The more aquaporins the determines the rate of osmosis
63
K+ (Postassium) is located where
cytosol
64
Na+ (Sodium) is located where
extracellular space
65
Ca+2 (calcium) is located where
extracellular space
66
Cl- (Chlorine) is located where
extracellular space
67
what is resting membrane potential?
difference in ion concentration leads to voltage across membran e
68
Electrochemical gradients are only used for
CHARGED IONS
69
passive transport is the movement _________
down the concentration gradient
70
active transport is the movement _________-
up the concentration gradient
71
active transport is only accomplished by
transporters
72
passive transport using transporters is also called _________; moves solutes _____ concentration gradient
facilitated diffusion; down
73
active transport needs
source of energy to pump solute
74
examples of gradient driven pumps
symport and antiport
75
The Na+/Glucose Symporter is a steep gradient of _____ used to move
Na+, used to move glucose UP its concentration gradient
76
Why are ion channels selective?
to ensure only the right ions pass through
77
What does it mean if ion channels are gated?
they are open or close
78
What are the major features of the neuron?
- Dendrites - Axon - Body (Soma)
79
Neurons are able to become _________ which allow them to alter ______ ________.
stimulated, membrane potential
80
the stronger the stimulus the stronger the ___________
depolarization
81
threshold where a large increase in membrane potential occurs
action potential
82
What are the two types of voltage gated ion channels
1. Na+ voltage gated ion channel 2. K+ voltage gated ion channel
83
Which ion channel moves "slow"
K+ voltage gated ion channel
84
Where are voltage gated ion channels found
In the axon
85
what happens when action potential reaches synapse
synaptic vesicles fuse together
Cellular Biology
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