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Biol 331 > Cell Membrane Introduction > Flashcards

Cell Membrane Introduction Flashcards

1
Q

When was the first plasma membrane discovered

What were its features

A

1950s

Three layered membrane, 5-10nm wide

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2
Q

What are membranes composed of

A

Lipids

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3
Q

What and when did Overton show about nonpolar solutes to support that membrane were made of lipids

A

Showed that nonpolar solutes were more rapidly taken up into the (plant root hair) cells

In 1890

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4
Q

What type of layer are membranes

A

Bilayer (made of two layers)

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5
Q

What did gortor and Grendel show and when

A

Show that lipids extracted from the red blood cell membrane could the cell twice
(Two layers)

Red blood cells don’t have interior membranes

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6
Q

What do membranes also contain

What does this mean?

A

Proteins

Means That lipids solubility isn’t the only thing that determines membrane penetrability (proteins do too)

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7
Q

What are the bilayers of membranes made of

What side face inside and outside

A

Phospholipids

The polar phosphates in the phospholipid face the outside

The nonpolar fatty acid tails face the inside (hydrophobic)

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8
Q

Phospholipids are

A

amphipathic

Has both hydrophilic and hydrophobic regions

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9
Q

What does the lipid bilayer of membranes prevent

A

Random movement of substances in and out of the cell

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10
Q

What are fatty acids

How long are they

A

Long unbranched hydrocarbon chains

Fatty acids in cells have 14-20 carbons

Can be saturated (no double bonds) or unsaturated (one or more double bonds)

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11
Q

What type of double bond gives more mend in the fatty acid tail

A

Cis

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12
Q

Naturally occurring fatty acid have what type of double bond

A

Cis

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13
Q

What are the three types of membrane lipids

A

Phosphoglycerides
Sphingolipids
Cholesterol

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14
Q

What are Phosphoglycerides

A

Are all phospholipids

Most membrane phospholipids are
Phosphoglycerides

Built on a glycerol backbone

Have glycerol, 2 fatty acids chains (one unsaturated) ,

Head made of a phosphate group, an additional group

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15
Q

What are the five types of phosphoglycerides

A

Phosphatidic acid. (h additional group)

Phosphatidylcholine (choline additional group)

Phosphatidylserine

Phosphatidyl ethanoamine

Phosphatidylinositol

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16
Q

What is the charge of Phosphatidic acid

A

-

17
Q

What is the charge of Phosphatidylcholine (choline additional group)

A

Neutral (but still polar)

18
Q

What is the charge of
Phosphatidylserine

A

-

19
Q

What is the charge of

Phosphatidyl ethanoamine

A

Neutral (but still polar)

20
Q

What is the charge of
Phosphatidylinositol

A

-

21
Q

What are sphingolipids

A

A less abundant type of membrane lipid

Amphipathic

Have longer and more saturated fatty acid chains than phosoglycerodes (less double bonds)

Play roles in signal transduction, membrane structure, sensing

22
Q

How did sphingolipids get their name

A

They were studies in the 1800s in brain tissues and compared to the sphinx in Egypt cause both were poorly understood at the time.

23
Q

What are the types of sphingolipids (how are they made)

Which are also phospholipids

A

Sphingosine (just backbone and head group)

Ceramide (backbone, head, and fatty acid)

Sphingomyelin (phosphorylcholine added to the head group) also a phospholipid

Cerebroside (adding simple sugar)

Ganglioside (adding complex sugar)

24
Q

What happens if a carbohydrate is added to a sphingolipid?

A

The molecule becomes a glycosphingolipid

Meaning some sphingolipids are also glycolipids

25
Q

If a simple sugar (galactose) is added to a sphingolipid is becomes a __

If a complex sugar (sialic acid) is added to a sphingolipid it becomes a ____

A

Cerebroside

Ganglioside (ex GM2)

26
Q

Where are glycosphingolipids most abundant

What happens if these lipids abundance are altered

A

In the nervous system

Neurological diseases occur (ex. Tay sachs where GM2 ganglioside builds up in the brain and impairs nerve cell function)

27
Q

What is cholesterol

What special about the tails

A

Makes up 20-30% of the plasma membrane lipids in animal cells

Has a small polar hydrophilic group (OH) facing membrane surface

The rest of the cholesterol is embedded in the phospholipids fatty acid tails

This bulky thing thats embedded impairs the move move t of the fatty acid tails

28
Q

What is the cytosolic region of the cell

A

The inside

29
Q

What is membrane lipid asymmetry

Give examples

A

When the lipids on the exoplasmic region are in diff amounts than the cytosolic region

Ex. There’s way more sphingomyelin and phosphotidyl choline on the exoplasmic

Cholesterol is equal amounts exoplasmic and cytosolic

30
Q

What does membrane asymmetry affect

A

Membrane permeability

The charge of the surface (diff additional groups)

Membrane shape

Stability

31
Q

What does PE do

PS

PI

A

Promotes curvature

The negative charge of it interacts with transmembrane protiens

Is plays roles in signal transduction

32
Q

What percent of carbohydrates are covalently linked to lipids?

What percent of carbohydrates are covalently linked to protiens?

What are each called

A

10% glycolipids

90% glycoproteins

They can have very diverse structures

33
Q

Where do all membrane carbohydrates in the plasma membrane face

A

The extracellular space

34
Q

What important roles to carbohydrates play

A

Role as receptors, sorting the membrane protiens, and cell recognition

35
Q

What is an example of cell recognition

A

Blood type antigen (ABO)

The antigen that recognizes and give either A or B blood types is a carbohydrate chain attached to a lipid in the red blood cell membrane

36
Q

Different biological membranes have ___

Give example

A

Different lipid compositions to help support their function (red blood cell, mitochondria, etc)

Ex. The myelin sheath is made of multiple plasma membrane layers with very little protein
because the more lipids density helps with propagation of electrical signals

37
Q

What can lipid composition determine

A

The physical state of the membrane

Facilitates protein interactions

Roles in signal transduction

38
Q

What is compartmentalizations

A

The membrane compartments in the cell allow special activities to occur without impacting each other

39
Q

What are the 7 major membrane functions

A

On slides

Biol 331 (18 decks)

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