Cell Membrane Introduction Flashcards
When was the first plasma membrane discovered
What were its features
1950s
Three layered membrane, 5-10nm wide
What are membranes composed of
Lipids
What and when did Overton show about nonpolar solutes to support that membrane were made of lipids
Showed that nonpolar solutes were more rapidly taken up into the (plant root hair) cells
In 1890
What type of layer are membranes
Bilayer (made of two layers)
What did gortor and Grendel show and when
Show that lipids extracted from the red blood cell membrane could the cell twice
(Two layers)
Red blood cells don’t have interior membranes
What do membranes also contain
What does this mean?
Proteins
Means That lipids solubility isn’t the only thing that determines membrane penetrability (proteins do too)
What are the bilayers of membranes made of
What side face inside and outside
Phospholipids
The polar phosphates in the phospholipid face the outside
The nonpolar fatty acid tails face the inside (hydrophobic)
Phospholipids are
amphipathic
Has both hydrophilic and hydrophobic regions
What does the lipid bilayer of membranes prevent
Random movement of substances in and out of the cell
What are fatty acids
How long are they
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)
What type of double bond gives more mend in the fatty acid tail
Cis
Naturally occurring fatty acid have what type of double bond
Cis
What are the three types of membrane lipids
Phosphoglycerides
Sphingolipids
Cholesterol
What are Phosphoglycerides
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
What are the five types of phosphoglycerides
Phosphatidic acid. (h additional group)
Phosphatidylcholine (choline additional group)
Phosphatidylserine
Phosphatidyl ethanoamine
Phosphatidylinositol
What is the charge of Phosphatidic acid
-
What is the charge of Phosphatidylcholine (choline additional group)
Neutral (but still polar)
What is the charge of
Phosphatidylserine
-
What is the charge of
Phosphatidyl ethanoamine
Neutral (but still polar)
What is the charge of
Phosphatidylinositol
-
What are sphingolipids
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
How did sphingolipids get their name
They were studies in the 1800s in brain tissues and compared to the sphinx in Egypt cause both were poorly understood at the time.
What are the types of sphingolipids (how are they made)
Which are also phospholipids
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)
What happens if a carbohydrate is added to a sphingolipid?
The molecule becomes a glycosphingolipid
Meaning some sphingolipids are also glycolipids
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 ____
Cerebroside
Ganglioside (ex GM2)
Where are glycosphingolipids most abundant
What happens if these lipids abundance are altered
In the nervous system
Neurological diseases occur (ex. Tay sachs where GM2 ganglioside builds up in the brain and impairs nerve cell function)
What is cholesterol
What special about the tails
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
What is the cytosolic region of the cell
The inside
What is membrane lipid asymmetry
Give examples
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
What does membrane asymmetry affect
Membrane permeability
The charge of the surface (diff additional groups)
Membrane shape
Stability
What does PE do
PS
PI
Promotes curvature
The negative charge of it interacts with transmembrane protiens
Is plays roles in signal transduction
What percent of carbohydrates are covalently linked to lipids?
What percent of carbohydrates are covalently linked to protiens?
What are each called
10% glycolipids
90% glycoproteins
They can have very diverse structures
Where do all membrane carbohydrates in the plasma membrane face
The extracellular space
What important roles to carbohydrates play
Role as receptors, sorting the membrane protiens, and cell recognition
What is an example of cell recognition
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
Different biological membranes have ___
Give example
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
What can lipid composition determine
The physical state of the membrane
Facilitates protein interactions
Roles in signal transduction
What is compartmentalizations
The membrane compartments in the cell allow special activities to occur without impacting each other
What are the 7 major membrane functions
On slides
