Chapter 6: 6.1 Lipids Flashcards
Describe:
Lipids
- Very diverse
- Insoluble in water, but soluble in organic solvents
- Can be divided into three main biological groups
State:
The 3 Main Biological Groups of Lipids
(Give examples)
- Storage Lipids (Triacylglycerols)
- Structural Lipids (Phospholipids, Sphingolipids, Glycolipids, Sterols)
- Signaling Lipids (Eicosanoids, Steroids)
What are fatty acids?
Building blocks for many different kinds of lipids
Describe:
Structure of Fatty Acids
Contains:
* A carboxylic acid group
* A carbon chain (2-22 carbons long)
* An additional methyl group at the end
What are the two forms of fatty acids?
- Saturated: Only single bonds
- Unsaturated: At least one double bond
What type of unsaturated fatty acids are there?
The double bond holds a:
* Cis conformation
* Trans conformation
Saturated fatty acids have been linked to…
Heart Problems
Trans-fatty acids are linked to…
Cardiovascular disease
True or False:
Fatty acids have to be linked together
False, they can remain individual as “Free Fatty Acids”
How can fatty acids be linked together?
- Linked together via ester bonds
- Remain individual as “Free Fatty Acids”
What are the two different ways of naming fatty acids?
- Structural
- Systematic (saturated and unsaturated naming schemes are different)
Describe and give example(s):
Structural Naming of Fatty Acids
[# C] : [# of Double Bonds] (Δ^position of double bonds)
* i.e. for an fatty acid with 18 carbon (no double bonds: 18:0
* i.e. the same fatty acid with two double bonds: 18:2 (Δ^6,8)
Describe and give example(s):
Systematic Naming of Saturated Fatty Acids
n-number of carbons-anoic acid
* i.e. for an fatty acid with 18 carbons: n-Octadecanoic acid
Describe and give example(s):
Systematic Naming of Unsaturated Fatty Acids
cis-position of carbon-enoic acid
* i.e. for fatty acid with 18 fatty acids and a single double bond: cis-6-octadecenoic acid
* i.e. for the same fatty acid with two double bonds: cis-6,8-octadecadienoic acid
What effect does the length of the carbon chain and number of double bonds have on the fatty acid?
- Longer the carbon chain, the higher the melting point of the fatty acid
- More double bonds, the lower the melting point of the fatty acid
State:
Relationship between membrane fluidity, unsaturated fatty acids, and melting temperatures
- A more fluid membrane = More unsaturated fatty acids = A lower melting temperature
- A less fluid membrane = Less unsaturated fatty acids = A higher melting temperature
Define:
Triacylglycerols (TAGs)
Energy reserves of the cell
Describe:
TAGs
Made up of three fatty acids joined by glycerol
Where are TAGs found?
Found in fat cells (adipocyte cells)
Can TAGs be found mixed together?
Yes, TAGs can be found as simple or mixed
Fats are varying compositions of…
Simple and mixed TAGs
What does TAG composition dictate?
Melting temperature
Define:
Glycerophospholipids
A structural membrane lipid
True or False:
Glycerophospholipids are the most abundant lipids in cellular membranes
True, they are one of the most abundant
Describe:
Glycerophospholipids
Has four components:
1. Fatty acids
2. Glycerol backbone
3. Phosphate
4. Head group
What can the net charges for glycerophospholipids be?
- Neutral (net neutral charge)
- Anionic (net negative charge)
Define:
Sphingolipids
The second most abundant membrane lipid
* Plays a role in signal transduction and cell recognition
Describe:
Sphingolipids
Structure is built off of sphingosine (an unsaturated 18-carbon amino alcohol)
What is a sphingosine?
An unsaturated 18-carbon amino alcohol
How are sphingolipids broken down?
Broken down in lysosomes through hydrolytic enzymes (Glucosidase)
What can defects in sphingolipids or their metabolic processes lead to?
Neurological disorders
* Gaucher disease etc.
Define:
Cholesterol
The third most common lipid in cellular membranes
* The most common steroid in mammals
Can a steroid be synthesized? Can a steroid be broken down?
Yes it can be synthesized but not broken down
What are the functions of cholesterol?
- Modulates membrane fluidity
- Increases membrane packing
- Reduces the permeability of the membrane
State:
The relationship between:
1. Cholesterol
2. Membrane fluidity
The more cholesterol, the less fluid the membrane
State:
The relationship between:
1. Temperatures
2. Membrane fluidity
3. Cholesterol
- At low temperatures, cholesterol prevents freezing by increasing fluidity
- At high temperatures, cholesterol reduces fluidity by adding rigidity
How are glycerophospholipids converted to fatty acids?
Phospholipases hydrolyze ester bonds in glycerophospholipids, coverting them to fatty acids
Define/describe:
Steroid hormones
Circulate through the blood to targeted tissues and relay messages
What is the base for all animal steroids?
Cholesterol
How do phospholipids contribute to signalling?
Through local chemical signals
True or False:
DIfferent phospholipases each break different bonds along the glycerol/carbon chain
True
What are the signalling molecules cleaved by phospholipases?
Precursors of eicosanoids
What are eicosanoid signalling pathways involved in?
- Inflammation
- Heat
- Pain
- Smooth muscle contraction
- Pregnancy etc.
Describe:
Eicosanoid Signalling
Caused by the breaking of bonds in glycerophospholipids by enzymes
