Biomembranes Flashcards

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1
Q

What are the basic components of bio membrane

A

Lipids Sterols and protiens

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2
Q

What does amphipathicity do

A

Phospholipis spontaneoutly form lipid bilayers in aqueous solution where the properties of the fatty acids confer properties on bilayers

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3
Q

What does saturated mean

A

No double bonds

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4
Q

What does unsaturated mean

A

One double bond

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5
Q

What does polyunsaturated mean

A

More than one double bond

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6
Q

What changes melting point

A

Increases with chain length decreases with increasing unsaturation

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7
Q

What is a fatty acid

A

Long hydrocarbon chain attached to a polar carboxyl head group

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8
Q

What are properties of biomemembranes

A
  1. Fluid
  2. Closed compartments
    3, Semi permeable
  3. Asymmetric
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9
Q

What makes a membrane more fluid

A

Increase in double bonds
Shorter fatty acids

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10
Q

What effects membrane fludity

A

Steriods
Protiens
Temperature if you are cold blooded
Double bonds
Fatty acid length

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11
Q

How can you measure flourence recovery

A

You bleache a cwertain area the flourcences from outside migrate in and the bleached will start to migrate out indirect measure on fluid things are

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12
Q

What makes fluidit slower

A

Diffusion is 10 x slower in plasma membranes that contain protiens than pure bilayers

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13
Q

What does cytosolic face mean for plasma membrane

A

Internal face

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14
Q

What does cytosolic face mean for vesicle membrane

A

External face

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15
Q

Where is the exoplasmic face

A

always facing the inside

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16
Q

What can pass through

A

Small uncharged or hydrophobic molecules pass freely

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17
Q

What cant pass through

A

Large hydrophillic or charged molecules

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18
Q

Where are carbohydrates found

A

Exclusively on the exoplasmic face

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19
Q

Where are protiens

A

Either embedded in the bilayer in a fixed orientation or are associated with only one side

20
Q

What are the three types of membrane protiens

A

Intergral
Lipid linked
Peripheral

21
Q

What are the three domains of integral membrane protiens

A

Cytoplasmic (hydrophilic)
(often amion acids such as Argo or lys)
transmembrane a or helix or b bareel
Exoplasmic domains are glycosylated

22
Q

How many amino acids are alpha helix

A

20-25

23
Q

What are lipid linked protiens

A

They have a GPI anchor
the exoplasmic requires sugar residues

24
Q

What is acylation

A

Aclyation attaches through N-termial of GLy

25
Q

What is prenylation

A

Attaches cys residuce at c terminus

26
Q

What are some characterstics of lipid-linked protiens

A

Protien does not eneter bilayer
Has lateral mobility in membrane

27
Q

What are peripheral protiens attached by

A

Attached through non-covalent interactions
Ionic interactions hydrogen bonds
Protien-protien interacations
Van der wall forces

28
Q

How can intergral protiens link to cytoskelton

A

Usin peripheral membrane protiens

29
Q

Where does translation occur

A

In the cytoplasma
Ribsomes will translate and continue to translate in the cytoplasam unless it has a reason not ot

30
Q

What does translation start with

A

N terminal domain
N terminal single is cleaved and that is what tells the protien to go to the ER

31
Q

What is STA

A

Stop transfer/membrane anchor sequence only be used to change protien from ER lumen to cytosol

32
Q

What is SA

A

Single anchor internal uncleaved sequecence

33
Q

What does a topogenic sequence do

A

Tell the ribsome what to do

34
Q

What are tail anchored protiens require

A

Get3 recognition of hydrophobic C-terminal tail, membrane embedded Get 1 adn 2 and Atp hydrolosys

35
Q

What are the steps of Tail anchored protiens

A

Hydrophobic c-terminal tail
Gets recgonized by Get3 and take it to the Er
Ger1 and Get 2 are also there
Using atp hydrolis it shoves the hydrophobic part into the membrane
no extracellular domain
Inserts hydrophobic tail and becomes an integral protien

36
Q

What are the steps of the type 1 protiens

A
  1. Translate N terminal sequence into the Er recognize the topogenic sequence then it is recognized to take to ER lumen
  2. Protien peptidase puts into a translocon
  3. Sequence gets cleavedoff
  4. N terminal domain if not other sequence would just be a lumen
  5. Get to the STA this a TM domain gets transfered
  6. Rest of the peptide is translated in the cytosol
37
Q

Steps of GPI- anchored protien

A

Starts like Type 1 portiens with N terminal in lumen and C terminal STA
Sequence near membrane is recognized by GP1 trasamidase which cleaves and transfers the luminal portion to the adjacent GPI
Later mobility
Since the STA is very close to the carboxyicl end it had no protien in the cytsol

38
Q

Synthesis of type 2 and type 3 protiens

A

have a SA
Orientation is determined by the positvely charged amion acids

39
Q

What end is in the cytsol in type 2

A

NH3

40
Q

What end is in the cytsol for type 3

A

COO

41
Q

How do you know which part will be in the cytsol

A

Have the charged particle right next to the NH3 that side will be in the cytsol
mean it is in the type 2
If the charge comes after the SA then the NH3 will be in the lumen and the COO in the cytsol

42
Q

Syntheis of Type 4 protiens

A

Orientation of initial helix is determined by positively charged amino acids next to signle anchor sequence
Have alternating SA and STA
Even or odd transmembrane domains

43
Q

What is type one

A

STA signal sequence gets cleaved and the NH3 ends up in the lumen

44
Q

What is type 2

A

Has an SA which an internal single that tells you where to go this is where the chared is on the NH3 side and it ends up in the cytsolol

45
Q

What is type 3

A

The charge is on the side of after the SA and the COO is ending up in the cytsol

46
Q

What is type 4 A

A

The positve charge is before the SA which makes the amino side in the cytsol and the COO is in the lumen and then it switches at the next STA

47
Q

What is type 4 B

A

You have 2 SA in a row
The spaces are the same
You have more Sa in the row
Start in the lumen