Lecture 15-16 Flashcards
Are lipids hydrophobic or hydrophilic?
BOTH! lipids are amphipathic
Name the specific hydrophobic and hydrophilic (polar) groups that are found on lipids and work to give them their amphipathic nature.
The hydrocarbon group is what is hydrophobic
The carboxyl group is what is hydrophilic (polar)
Describe what it means for a lipid to be “saturated” and compare that to an “unsaturated” lipid
Saturated lipids have the maximum number of hydrogens that can be bound to their carbon chain
Unsaturated lipids have “at least one double bond” (this occupies at least one of the places that a hydrogen could have been bonded
Compare Saturated and Unsaturated fatty acids in terms of their Melting points, Flexibility, C-C bonds, and C=C bonds.
Saturated Fatty acids:
Melting point: Higher
Flexibility: High
C-C Bonds: All of it’s carbon carbon bonds
C=C Bonds: none of it’s carbon carbon bonds
Unsaturated Fatty acids: Melting point: Lower Flexibility: Low C-C Bonds: Many C=C Bonds: occur in either "cis or trans" formations
Compare Saturated, Cis-unsaturated, and Trans-unsaturated fatty acids in terms of the shape of their hydrocarbon chain and dietary sources of them
Saturated Fatty acids:
Linearly shaped hydrocarbon chain
Animal fats
Cis-unsaturated Fatty acids:
“more bent” hydrocarbon chain
Plant oils and omega fatty acids
Trans-unsaturated Fatty acids:
“less bent” hydrocarbon chain
Processed fats
Palmitoleic, Oleic, Linoleic, Linolenic, Arachadonic Acids, EPA and DHA are all considered to be what type of fatty acid?
Cis-unsaturated fatty acids
Lauric, Myristic, Palmitic, Stearic, Arachidic, Behenic, an Linoceric Acids are all considered to be what type of fatty acid?
Saturated fatty acids
“partially hydrogenated oils” are considered to be what type of fatty acids?
Trans-unsaturated fatty acids
Define micelles (include what forms them)
Micelle: a fatty acid that forms a “wedge-shape” and tend to take on spherical forms
(like an ice cream cone)
Describe which end you begin on when naming/numbering a fatty acid
begin from the carboxyl-end (functional group: O-C-O ; Alpha carbon) and count toward the Methyl-end (functional group: CH3 ; Omega Carbon)
In terms of Omega Fatty acids, explain what the number in the names mean. (ex. omega 3 and omega 6 fatty acids)
The number represents the position of the double bond closest to the methyl (w) group end of the structure of the fatty acid
So omega 3 fatty acids have a double bond 3 carbons away from the methyl group carbon and the double bond is 6 carbons away from the methyl group in omega 6 fatty acids
State the 4 “essential” omega fatty acids but be sure to delineate which of these are considered to be essential omega fatty acids bc they are inefficiently converted (as opposed to just not being able to synthesize them at all).
Essential omega fatty acids
LA/Linoleic Acid (w-6)
ALA/Linolenic Acid (w-3)
ALA is inefficiently converted to
EPA (w-3)
DHA (w-3
State the role that omega fatty acids play in humans at the cellular level, nutrition level, and which particular body system they are shown to help the most
Omega fatty acids are used in cell membranes
they are a common energy source
They improve cardiovascular health
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Laurate
of Carbons: 12
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Myristate
of Carbons: 14
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Palmitate
of Carbons: 16
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Stearate
of Carbons: 18
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Arachidate
of Carbons: 20
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Behenate
of Carbons: 22
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Lignocerate
of Carbons: 24
of Double Bonds: 0
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Palmitoleate
of Carbons: 16
of Double Bonds: 1
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Oleate
of Carbons: 18
of Double Bonds: 1
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Linoleate
of Carbons: 18
of Double Bonds: 2
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Linolenate
of Carbons: 18
of Double Bonds: 3
Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.
Arachidonate
of Carbons: 20
of Double Bonds: 4
Describe the structure of a TAG (Triacylglycerol)
Triacylglycerols have 2 parts:
1. a glycerol which serves as the polar head
- 3 fatty acid chains (tails) that are hydrophobic
Describe the structure of a Wax (is it hydrophobic or hydrophilic?)
Waxes are similar to TAGs, except they have an alcohol group instead of a glycerol
Waxes are almost entirely hydrophobic
Archaebacteria lipid membranes contain branched fatty acids. Describe what a branched fatty acid structure is like.
Branched fatty acids: have many methyl groups “branching” off of the carbon chains of the fatty acids
State the 3 types of cell membrane lipids found in humans
Phospholipids
Glycolipids
Cholesterol
What type of lipid comprises the majority component of cell membranes? what 4 subunits must be included in the structure of this lipid?
Glycerophospholipids
they contain: An Alcohol group (hydrophilic group) A glycerol A phosphate Fatty acid chains
Some of the common alcohols that are added to create a glycerophospholipid can be divided into 3 groups, AA’s, Sugar-alcohols, and organic alcohols. State the 5 specific alcohols and put them in their appropriate group.
AA’s:
Sugar-alcohols:
Organics:
AA’s: Serine
Sugar-alcohols: Inositol or Glycerol
Organics: Ethanolamine or Choline
Which type of glycolipid is important for ABO blood type antigens and cell signaling? State the 3 subunits that these feature.
Glycosphingolipids
They contain:
A sugar unit (glucose or galactose)
A sphingomyelin unit (which attaches a fatty acid to it’s amine group)
A fatty acid unit
Which type of glycolipid is mainly found in plants and bacteria (rarely found in animals)? State the 3 subunits that these feature.
Glycoglycerolipids
They contain:
A carbohydrate
A glycerol
a fatty acid
What lipid is known to add rigidity to cell membranes? What is the category of lipid that this is a part of? what is the term that is used to describe a collection of these in a blood vessel?
cholesterol, which is a sterol
a plaque
When multiple hydrocarbon tails are present, lipids will form what structure? State the 2 parts that compose the “dual role” of this structure.
a bilayer
- A 2-D liquid that allows lateral movement of proteins and lipids
- A permeability barrier
Cell membranes are made up of several different types of structures that allow for their _____ natures. Name these 3 types of molecules that compose the cell membrane.
Flexible
- Lipids
- Proteins
- Carbohydrates
In terms of the roles they play in the cell membrane, compare lipid bilayers and carbohydrates
Lipid bilayers are the “base component” of cell membranes
Carbohydrates decorate lipids and proteins but are ONLY presented on the surface of the cell (NOT in contact with the cytosol)
Compare Integral membrane proteins with peripheral membrane proteins in terms of their location in relationship to the lipid bilayer
Integral membrane proteins: span the ENTIRE width of the lipid bilayer
Peripheral proteins span only part of the width of the lipid bilayer
Define cotranslational insertion and why it is important
Cotranslational insertion: The process by which an integral membrane protein is translated by a ribosome into the cell membrane THEN undergoes folding while already inhabiting the cell membrane
This is important bc it solves the issue of transporting integral membrane proteins into the cell membrane. Membrane proteins have a lot of hydrophobic AA’s displayed on their surfaces, which makes them want to clump together in the aqueous cytoplasm. Inserting them into the PM DURING translation avoids this issue.
Describe the 2 types of membrane anchors and explain what they are usually attached to
Hydrophobic AA side chains can serve as membrane anchors
Fatty acid groups can also serve as membrane anchors
Membrane anchors are hydrophobic proteins that are used to anchor peripheral membrane proteins into the PM
Membrane proteins (that includes integral and peripheral membrane proteins) make up what percentage of the proteome of a cell? Besides being heavily involved in signaling and molecule movement across the membrane, what 2 membrane characteristics are membrane proteins responsible for determining?
30%
Membrane proteins help to determine the “thickness and rigidity” of the membrane
Lipids are ___fluids, which means they allow only Lateral movement of components. Compare the speed of lateral diffusion and transverse diffusion.
2-D
Lateral diffusion is the movement of a lipid “Within the same surface of the membrane” and it is very rapid
Transverse diffusion is the movement of a lipid “to the other surface of the membrane” is very slow
(flip-flop movement of a lipid)
Compare what determines the rigidity of the membrane in a bacterial cell and a human cell
In bacteria, the rigidity of the PM is determined by it’s “fatty acid composition”
In humans, the rigidity of the PM is determined by it’s “cholesterol content”
Membranes are _______ in nature
asymmetrical
(meaning that the membrane proteins, cholesterols, glycoproteins, carbohydrates, etc. that composes the PM will not all be “equal on both sides”)
