Lipid Membranes Flashcards
Lipids are ______
Amphipathic, meaning they have both hydrophilic and hydrophobic properties
What is the structure of a lipid/fatty acid?
Hydrocarbon and Carboxyl group
Fatty acids can be ____ or ______
saturated (no double bonds) or unsaturated (has double bonds)
What is the MP of saturated compared to unsaturated
Saturated- Higher
Unsaturated- Lower
*Note that shorter fatty acids melt at lower temperatures than longer fatty acids
What is the Flexibility of saturated compared to unsaturated
Saturated- High
Unsaturated- Low
What is the C-C bonds of saturated compared to unsaturated
Saturated- All
Unsaturated- Many
What is the C=C bonds of saturated compared to unsaturated
Saturated- None
Unsaturated- Cis/Trans
What is the Shape of saturated compared to unsaturated
Saturated- Linear
Unsaturated- Cis (Bend More), Trans (Bent Less)
What is the Dietary Source of saturated compared to unsaturated
Saturated- Animal Fats (ex. butter/lard)
Unsaturated:
Cis- Plant Oils (Olive oil) and Omega Fatty Acids
Trans- Processed fats
What are the examples to know of saturated fatty acids
MBA PSLL
Saturated:
Myristic Acid
Behenic Acid
Arachidic Acid
Palmitic Acid
Stearic Acid
Lignoceric Acid
Lauric Acid
What are the examples to know of unsaturated fatty acids for cis and trans
Cis:
POLL DEA
Palmitoleic Acid Oleic Acid Linoleic Acid Linolenic Acid Arachidonic Acid EPA and DHA
Trans- Partially hydrogenated oils
What is a micelle?
Circles that fatty acids form when introduced to a hydrophilic environment like water
Hydrophilic heads are on the outside
Hydrophobic tails are pointing to the inside
How do you number the fatty acids?
Start with 1 on the first carbon of the carboxyl group and the second carbon is called alpha, 3 is beta, etc.
When you see n- or cis-/trans-, what does this tell you about in the fatty acid?
These tell you exactly what is in the fatty acid
n- means it is unsaturated
cis-/trans- means the type of double bond(s)
What does it mean if the fatty acid ends in:
- an
- en
- dien
- trien
- tetraen
- oic Acid
- oate
- an means saturated
- en –> 1 double bond
- dien –> 2 double bonds
- trien –> 3 double bonds
- tetraen –> 4 double bonds
- oic Acid means protonated/acid
- oate means deprotonated/conjugate base
What ∆^# mean for a fatty acid?
It denotes the number of carbons from the carboxyle end the double bond is located
How many carbons does hexadecanoid acid have?
16
Describe the common naming method of fatty acids
The first number defines the total number of carbons
The second number defines the total number of double bonds, but not their locations
15:2
Describe: Stearate (18:0) Oleate (18:1) Linoleate (18:2) Linolenate (18:3)
Stearate (18:0)- 18 carbons with 0 double bonds
Oleate (18:1)- 18 carbons with 1 double bond
Linoleate (18:2)- 18 carbons with 2 double bonds
Linolenate (18:3)- 18 carbons with 3 double bonds
How are Omega fatty acids named?
For their position of the double bond closest to te methyl end of the fatty acid, in other words you count from the end of the carbon chain till you hit the next double bond.
Omega-3 means no matter the length of the fatty acid the double bond is 3 carbons from the end
What are the 5 Omega-3 Fatty acids and their 3 letter names?
If you take LSD –> You go to the ED
Linolenic Acid (18:3)/ALA Strearidonic Acid (18:4)/SDA Docosapentaenoic Acid (22:5)/DPA Eicosapentaenoic Acid (20:5)/EPA Docosahexaenoic Acid (22:6)/DHA
What are the 3 Omega-6 fatty acids and their 3 letter names?
Linoleic Acid (18:2)/LA Arachidonic Acid (20:4)/AA Docosapentaenoic Acid (22:5)/DPA
What are the 2 omega fatty acids that cannot be synthesized by humans?
Linoleic Acid (18:2)/LA an Omega-6 Linolenic Acid (18:3)/ALA an Omega-3
Linolenic Acid (18:3)/ALA is inefficiently converted into what two other omega fatty acids?
EPA(20:5) Omega-3
DHA (22:6) Omega-3
What are 3 important functions of Omega fatty acids?
Used in cell membrane and other important lipids
A common energy source
Promote cardiovascular health
What are the 2 parts of triacylglycerols (TAGS)?
Polar head- Glycerol
Hydrophobic Tails- 3 fatty acid chains
How are waxes similar to triacylglycerols?
Same structure except they have an alcohol rather than a glycerol as a polar head group
Describe the lipid structure of Archaebacteria
Archael lipid membranes contain branched fatty acids
What are the 3 categories of cell membrane lipids?
Phospholipids- contain phosphates
Glycolipids- contains sugars
Cholesterol
__________ are the majority component of cell membranes
Glycerophospholipids
What is the structure of a glycerophospholipid?
2 fatty acids connected to a glycerol
Glycerol connected to a phosphate that is connected to an alcohol
What are the common alcohols that are added to the phosphate in glycerophospholipids?
Amino acids= Serine
Sugar-Alcohols= Inositol, glycerol
Organics= Ethanolamine, Choline
_______ attaches a fatty acid to an amine
Shingomyelin
What are Glycosphingolipids important for?
ABO blood type antigens
Cell signaling
What are the components of a Glycoglycerolipid?
Carbohydrate
Glycerol
Fatty acid
Carbohydrate attached to a glycerol, which is attached a fatty acid
Where do we find Glycoglycerolipids?
They are found in plants and bacteria, but rarely in animals
What adds rigidity to cell membranes?
Cholesterol
What are the 2 functions of a lipid bilayer?
- A 2-D liquid that allows lateral movement of proteins and lipids
- A permeability barrier
What composes the cell membrane?
Lipids
Proteins
Carbohydrates
What is the main component of the Fluid Mosaic Model?
Phospholipid bilayer
Where do you find carbohydrates?
On the surface of lipids and proteins and they are NOT in contact with the cytosol because that is found inside the cell
Where are integral membrane proteins found?
Inserted in the membranes and the span the entire width of the lipid bilayer
Membrane proteins have lots of ______ amino acids displayed on their surfaces. What is good and bad about this?
What is the solution to this?
Hydrophobic
Because they are:
Good for living in a hydrophobic environment
Bad if the cytoplasm of the cell is aqueous
Solution: Cotranslational insertion- prevents hydrophobic amino acids from coming into contact with the aqueous cytosol.
Where do you find peripheral membrane proteins?
They span only part of the width of the lipid bilayer
Membrane anchors are ______
Hydrophobic
Membrane proteins consitute _______ of the proteome
30%
What are the 5 functions of membrane proteins?
Receive exteral signals Transmit signals into cytoplasm Transmit signals to another cell Allow solutes through the membrane Help to determine membrane thickness and rigidity
Lipids are 2-D fluids, allowing only _____ _____ of components.
Lateral Movements
In bacteria, what determines the rigidity of the membrane?
The fatty acid composition
Whereas in humans this is determined by cholesterol
Membranes are ______ in structure
Asymmetrical
Which movement is faster within the membrane, lateral or transverse diffusion?
Lateral diffusion is faster
Transverse diffusion is vertical flipping from one side of the bilayer to the other, and that is very slow
Fatty acids are primarily hydrophilic or hydrophobic?
Hydrophobic
What is a common source for Omega Fatty Acids?
Fish Oil
What is more useful, systematic names or common names of fatty acids?
Which will we see more in the medical field?
Systematic names are more useful for identifying the structure of the fatty acid
We will see the common name more in the medical field
How many Angstroms is the width of the lipid bilayer?
What about for just the hydrophobic region?
Convert this to nm’s now
Lipid bilayer= 60-100 Angstroms
Hydrophobic Region= 30 Angstroms
10 Angstroms= 1nm
If a carbohydrate is found on the surface of the cell, in which direction does it face, toward the inside of the cell or towards the outside?
To the outside of the cell because carbohydrates do not come into contact with the cytosol/cytoplasm of the cell, which is found within the cell
If a carbohydrate is found on the surface of an organelle, in which direction does it face, toward the inside of the organelle or towards the outside?
Toward the inside of the organelle because carbohydrates do not come into contact with the cytosol/cytoplasm of the cell, which is found outside of organelles
What allows for both vertical and lateral movement of components in lipids?
Heat
