Exam 2 Study Guide - Lipids Flashcards
Fatty acids – know the basic structure.
Carboxylic acids with hydrocarbon tails ranging from 4 to 36 carbons long
Be familiar with the common fatty acids.
Palmitic, linoleic, and arachidonic acid
Saturated vs unsaturated fatty acids.
Saturated fats (unbranched) are solid at room temperature, whereas unsaturated fats (branched) are liquid at room temperature
Delta system.
Chain length and number of double bonds, separated by a colon; positions of double bonds are indicated by and superscript number
Omega system.
Labeled omega and by double bond between most distant carbon
What is the difference between cis and trans bonds
- Cis bonds have hydrogen atoms on same side of double bond, resulting in a bent shape
-Trans bonds have hydrogen atoms on opposite sides of double bond
Triacylglycerols: Know the basic structure
Three fatty acids, each in ester linkage with a single glycerol (non-polar, hydrophobic)…provide energy storage and insulation
Waxes: Basic structure
Esters of long-chain saturated and unsaturated fatty acids with long-chain alcohols
Where are waxes found.
Bee honeycomb, leaves of plants, feathers
Properties of waxes.
Higher melting point than triacylglycerols, water-repellant, firm consistency
Biological membranes: Structure
- A double layer of lipids that act as a barrier to polar molecule and ions
- Amphipathic (one end is hydrophobic, the other hydrophilic), Hydrophobic (regions associate with each other), Hydrophilic (regions associate with water)
Phospholipids: Composition
Have hydrophobic regions composed of two fatty acids joined to glycerol or sphingosine
Phospholipids: Basic structure
Two fatty acids are attached in ester linkage to the first and second carbons of glycerol, and a highly polar group is attached through phosphodiester linkage to the third carbon
Sphingolipids: Composition
Have a polar head group and two nonpolar tails, no glycerol, one molecule of the long-chain amino alcohol sphingosine
Sphingolipids: Role in blood types
Human blood groups (O, A, B) are determined by the oligosaccharide head groups of sphingolipids
Glycolipids: Role in chloroplasts
Oxygenic photosynthesis (thylakoid membrane); lipid bilayer matrix for photosynthetic protein cofactor complexes and support the ETC (electron transport chain)
Archaeal tetraether lipids: General composition
Have two very long alkyl chains ether-linked to glycerol at both ends
Sterols: Basic structure
Rigid system of four fused hydrocarbon rings; planar and rigid
Cholesterol: Role in membranes
Structural components of eukaryotic membranes
Cholesterol: Hormone example
estradiol
Bile acids: What are they?
Polar derivatives of cholesterol that emulsify dietary fats in the intestine to make them more readily accessible to digestive lipases
Intracellular signaling
Regulate cell structure and metabolism
Intercellular signaling
- Ex. Eicosanoids: paracrine hormones that act only on cells near the point of hormone synthesis instead of being transported in the blood
- Reproductive function, inflammation, fever, pain, regulation of blood pressure, etc.
Steroid hormones
Oxidized derivatives of sterols (lack alkyl chain attached to D ring in cholesterol) move through the bloodstream to target tissues
Explain why glycerophospholipids make good membrane components.
Glycerophospholipids are membrane lipids in which two fatty acids are attached in ester linkage to the first and second carbons of glycerol, and highly polar group is attached through a phosphodiester linkage to the third carbon. They can vary in the fatty acid content and the composition of the polar head group. Having a polar head group, allows this membrane lipid to arrange themselves into a membrane bilayer; thus, providing stability. Lastly, the head group can bear a negative, neutral, or positive charge. These characteristics make them amphipathic (hydrophobic and hydrophilic region) allowing for permeability and fluidity in the membrane.
