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BI 338 Cells > Biomembranes I (Lecture 7) > Flashcards

Biomembranes I (Lecture 7) Flashcards

1
Q

The core of the phospholipid bilayer is ______ and the faces of it are ______.

A

Hydrophobic

Hydrophillic

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2
Q

True or False: Biological membranes are impermeable to water-soluble molecules and ions.

A

True

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3
Q

What can you use to measure the lateral diffusion of the phospholipid bilayer.

A

FRAP

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4
Q

True or False: Heat makes the bilayer more rigid.

A

False, more fluid

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5
Q

______ face always faces the cytoplasm and ______ always faces the cell exterior or interior lumen.

A

Cystolic, Exoplasmic

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6
Q

What are the two functions that membrane fluidity and flexibility help with?

A

Enables organelles to assume their typical shapes

Provides dynamic property that enables membrane budding and fusion

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7
Q

What are the 3 types of phospholipid arrangements:?

A

Liposome, Micelle, Bilayer sheet

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8
Q

A smaller polar head favours?

A

inverted micelles or cubic structures

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9
Q

Similar polar head and hydrophobic region favious?

A

Bilayers

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10
Q

Bulky polar head and only one acyl chain favours?

A

Micelles

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11
Q

True or False: All phospholipids are amphipathic.

A

True

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12
Q

True or False: Phosphoglycerides are most common.

A

True, phosphoglycerides are most common

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13
Q

What are the 3 types of sterols found in animals fungal and plants?

A

Cholesterol (animals) —Ergosterol (fungal)

Stigmasterol (plant)

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14
Q

What is the tripartite structure of nucleotides?

A

Base + Sugar + Phosphate

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15
Q

What is the tripartite structure of phosphoglycerides?

A

Head group + backbone + fatty acyl tails

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16
Q

Sphingolipids are attached by what kind of bond?

A

Amide

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17
Q

True or False: Cholesterols are amphipathic lipids.

A

True, Polar head group

Tail, conjugated four ring hydrocarbon and short hydrocarbon chain

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18
Q

True or False: Phosphoglycerides, sphingolipids are all sterols.

A

False, while all phosphoglycerides are phospholipids, only certain sphingolipids are, and no sterols are.

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19
Q

What two lipid components are found mostly in the inner leaflet.

A

Phosphatidylethanolamine

Phosphatidylserine

20
Q

Where are phospholipids synthesized?

A

Cytosolic face of endoplasmic reticulum

21
Q

What enzyme allows PC (a phospholipid) found in the exoplasmic face of plasma membrane.

A

Flippases

22
Q

______ is synthesized on exoplasmic face of Golgi

complex.

A

Sphingomyelin

23
Q

True or False: There is more sphingomyelin in ER membrane than golgi membrane.

A

False, more in golgi and ER membranes

24
Q

True or False: Cholesterol helps maintain natural fluidity of membranes.

A

True

25
Q

______ cholesterol levels the steroid ring separates and disperses phospholipid tails and increases fluidity and at ______ cholesterol level it tends to decrease biomembrane fluidity at typical cholesterol concentrations.

A

Low, High

26
Q

True or False: Cholesterol has no effect on membrane thickness.

A

False, it influences membrane thickness

27
Q

Small polar head groups have what type of phosphoglycerides?

A

PE, PS

28
Q

Similar polar head groups have what type of phosphoglycerides?

A

PC PG PI

29
Q

Bulky polar head groups have what type of phosphoglycerides?

A

Lysolipids

30
Q

______ are found more in the outer leaflet, ______ are found in both leaflets and ______ are found more in the inside leaflet.

A

Lysolipids
PC PG PI
PE PS

31
Q

Where does excess lipid storage occur?

A

In ER membrane through insertion of triglycerides and cholesterol esters

32
Q

What are the three types of proteins in the biological membranes?

A

Integral, lipid-anchored and peripheral proteins

33
Q

______ are membrane proteins (aka transmembrane proteins) contain one or more hydrophobic membrane-spanning domains.

A

Integral

34
Q

Integral proteins are made ip of ______ typical 20-25 amino acids and typically made up of ______ residues

A

α-helix, hydrophobic

35
Q

True or False: “Multipass” proteins have multiple transmembrane helices

A

True

36
Q

True or False: Polar or charged residues in transmembrane helices need to be sequestered away from the hydrophobic lipid bilayer core

A

True

37
Q

______ are made up of B-barrels and are found in outer membrane of gram negative bacteria, mitochondria and chloroplasts

A

Porins

38
Q

True or False: The B-barrel has a hydrophilic interior and a hydrophobic exterior.

A

True

39
Q

______ are proteins that are bound covalently to one or more lipid molecules.

A

Lipid anchored

40
Q

True or False: In lipid anchored proteins, ther lipid may be at the N- or the C-terminus of the polypeptide

A

True

41
Q

GPI anchordd is attached to the ______, Prenylation is attached to the ______ and acylation is attached to the ______.

A

C terminus, C terminal Cys, N-terminal Gly

42
Q

True or False: Membrane proteins do flip-flop when forming a vesicle.

A

False, do not flip flop

43
Q

______ is the word known as the membrane no flip flopping.

A

Topology

44
Q

______ proteins do not directly contact the hydrophobic core of the membrane.

A

Peripheral

45
Q

What are lipid binding motifs used for?

A

Degrade damaged/aged
cellular membranes

Generate signaling molecules

BI 338 Cells (21 decks)

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