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Biology > Biomembranes > Flashcards

Biomembranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the basic components of a biomembrane

A

Lipids Sterols and protiens

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2
Q

What does a membrane do

A

Allow specialized functions to occur in a localized manner

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3
Q

What is the reason that lipid bilayer spontanousley form in an aqueous solution

A

amphipathicity

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4
Q

What properties interact with properties onto the bilayers

A

Fatty acids

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5
Q

What is the formation of the fatty acid chain

A

Long hydrocarbon chain attached to the poral carboxyl head group

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6
Q

What does Cx:y stand for

A

x= number of carbon molecules
y=number of double bonds

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7
Q

What does the pressence of double bonds mean

A

No double bonds= saturated
One double bond= unsaturated
More than one double bond= polyunsaturated

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8
Q

How does the chain length have an effect on melting point

A

The melting point increases with chain length

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9
Q

How does saturation have an impact on melting point

A

Decreases with the ammount of unsaturation so the more double bonds the lower the melting point

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10
Q

What componets of membrane lipids to fatty acids use

A

Phospholipids phosphoglycerides sphingolipids
Sterols

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11
Q

What are the properties of biomembranes

A
  1. Fluid
  2. Closed compartments
  3. Semi permeable
  4. Asymmetric
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12
Q

What are the two dimensional fluids

A

rapid lateral diffusion
slow (rare) transverse (flip-flop) movement between leaflets

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13
Q

What are things that contribute to fludity

A

fatty acid lenfth and cis double bonds
steroids
protiens (lateral difusion link to cytoskelton)
temperature effects modify membrane of fluid if you are cold blooded

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14
Q

What makes diffusion slower

A

Diffusion is slower in plasma membranes that contain protiens than pure bilayers
because the distance that is moved may be resitrected by protiens

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15
Q

What is the cyosolic face in a plasma membrane

A

The internal face

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16
Q

What is the cytosolic face in an vesicle membrane

A

external face

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17
Q

What crosses the membrane freely

A

Small uncharged or hydrophobic molecules pass freely

18
Q

What doesnt cross the membrane freely

A

Large hydrophilic or charged molecules

19
Q

Do phospholipid composition differ between leaflets

A

Yes

20
Q

Where are carbohydrates found

A

On the exoplasmic face

21
Q

Where are protiens on the membrane

A

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

22
Q

What are the three types of membrane protiens

A
  1. Integral
  2. Lipid-linked
  3. Peripheral
23
Q

Are membrane protiens symmetric or asymmetric

A

Asymmetric

24
Q

What are the three domains of integral membrane protiens

A

Cytoplasmic (hydrophilic)
Transmembrane (hydrophobic)
Exoplasmic (hydrophilic)

25
Q

What is apart of the cytoplasmic domain

A

Amino acids such as arg and lys
the charged amino acids are near the cytosolic side to interact with polar head groups

26
Q

What structure is the transmembrane domain

A

Hydrophobic secondary or tertiary structures that span the lipid bilayer. Generally an alpha helix or a b barrel

27
Q

What is part of the exoplasmic domain

A

They are mostly glycosylated

28
Q

What are some traits about the GPI anchor

A

exoplasmic and requires sugar residues

29
Q

What is acylation

A

It attaches through the N-terminal Gly residue

30
Q

What is prenylation

A

Prenylation attaches Cys resiude ar or near C terminus

31
Q

Does the polyepetide chain of lipid linked protiens enter the bilayer

A

NO

32
Q

What type of mobility does lipid link protiens have

A

Lateral

33
Q

How are peripheral protiens attached

A

Through non-covalent interacations such as ionic interacations, hydrogen bonds and protien-protien interacations and van der waals forces

34
Q

What filaments can associate with the bilayer through peripheral protiens

A

Cytoskelton filaments and ECM components

35
Q

What are components of Topogenic Sequences

A

N-terminal (cleaved) signal sequence
Stop-transfer/membrane anchor sequence
Signal anchor- Internal (uncleaved) sequence (SA)
Hydrophobic C-terminus

36
Q

What is the steps of tail anchored protiens

A

You have a hydrophobic c terminal tail that is recognized by Get 3 it then takes its way to the ER where it attaches to Get 1 and Get 2 it then goes into atp hydrolosis which shoves the hydrophobic part into the membrane and there are no extracellular domain

37
Q

What are the steps of syntheis 1 type protien

A

the first thing that gets translated is the N terminal signal sequence which takes it to the ER this then gets cleaved by a peptidase it will then continue to translate the NH3 side until it is told not to by an STA once it comes across the STA it will become a transmebrane domain the rest of the product is now in the cytosol

38
Q

What is the difference between GPI-anchored protiens and Type 1

A

The GPI protiens o through the same process but then a sequence near membrane is recognized by GPI-transamidase whcih will cleave the and trasnfer the luminal portion to an adjacent GPI there is no carboxiclye end of the protien

39
Q

How is a type 2 protein inserted into the membrane

A

Type 2 has an SA sequence meaning that it is internal and is a charge it goes through teh same process as type one but in type two the SA the charge on the side of the amino end therefore the carboxyci=il end is in the lumen and Nh3 in the cytosol type three is vis versa

40
Q

How is the syntheis of Type 4 protiens

A

Orientation of inital helix is determined by positively charged amino acids next to signal-anchor (SA) sequence
Have alternating singal-anchor (SA) sequence and STA
Can have an even or odd number of transmembrane domains

41
Q

Whats is the difference between Type 4 A and Type 4 B

A

Type 4 B has an uneven number of domains it also has more and it has two SAs in a row and then continues to alternate after that
Type A has an even number

Biology (11 decks)

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