Biochemistry: Ch 10 Lipids – Flashcards
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A diverse group of molecules that contain regions composed almost entirely of hydrogen and carbon, with non-polar carbon hydrogen bonds. Insoluble in water (hydrophobic).
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Lipids
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4 Biological Functions of Lipids
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1. Energy Storage 2. Insulation from Environment 3. Water Repellant 4. Buoyancy Control and Acoustics in Marine Animals
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Very large region in the head of the sperm whale especially that helps with echolocation and may aid buoyancy
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Spermaceti Organ
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5 More Functions of Lipids at a Cellular Level
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1. Membrane Structure (main structure of cell membrane) 2. Cofactors for Enzymes 3. Signaling Molecules (i.e., paracrine hormones, growth factors) 4. Pigments (color of tomatoes, carrots pumpkinds, birds) 5. Antioxidants (i.e., Vitamin E)
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Hydrocarbon chains containing between 4-36 carbons.
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Fatty acids
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Almost all natural fatty acids have a(n) ___ # of carbons.
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Even
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Most natural fatty acids are __.
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Unbranched
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Have the maximum number of hydrogen atoms possible and no double bonds. They're solid at room temperature.
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Saturated Fatty Acid
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A fatty acid whose molecular structure includes only one double carbon bond in the alkyl chain.
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Monounsaturated Fatty Acid
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A fatty acid containing two or more double bonds on the carbon chain.
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Polyunsaturated Fatty Acid
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Delta-x (?^x) nomenclature
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each double bond is indicated by ?^x, where the double bond is located on the xth carbon-carbon bond, counting from the carboxylic acid end. Each double bond is preceded by a cis- or trans- prefix, indicating the conformation of the molecule around the bond. For example, linoleic acid is designated "cis-?^9, cis-?^12 octadecadienoic acid".
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N?x nomenclature
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Aka: ?-x. A double bond is located on the xth carbon-carbon bond, counting from the terminal methyl carbon (designated as n or ?) toward the carbonyl carbon. For example, ?-Linolenic acid is classified as a n?3 or ?-3 fatty acid.
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Lipid numbers
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They take the form of C:D, where C is the number of carbon atoms in the fatty acid and D is the number of double bonds in the fatty acid (if more than one, the double bonds are assumed to be interrupted by CH 2 units, i.e., at intervals of 3 carbon atoms along the chain). When ambiguity exists, this notation is usually paired with either a ?^x or n?x term. Examples: 18:3 18:3?6 18:3, cis,cis,cis-?^9,?^12,?^15
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What essential nutrients do humans need but cannot synthesize themselves?
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Omega-3 fatty acids
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Fatty acid solubility __ as chain length increases.
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Decreases
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Fatty acid melting point decreases as chain length __.
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Decreases
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Fatty acid melting point decrease as double bonds __.
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increase
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The double bonds in natural unsaturated fatty acids are commonly in ___ configuration, which __.
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Cis configuration/kinks the chain.
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Saturated fatty acids pack in __.
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a fairly orderly way (extensive favorable interactions).
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What makes unsaturated cis fatty acids pack in less orderly?
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Kinks (less-extensive favorable interactions)
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It is thermally __ to disrupt disordered packing than ordered.
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Easier
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Unsaturated cis fatty acids have a __ melting point than saturated fatty acids.
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Lower
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How are trans fatty acids formed?
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Partial dehydrogenation of unsaturated fatty acids.
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For what does a trans double bond allow?
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It allows a given fatty acid to adopt an extended conformation and stay liquid.
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Does trans fatty acid or cis fatty acid have a higher melting point?
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Trans
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The majority of fatty acids in biological systems are found in the form of ____.
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Triacylglycerols
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Solid triacylglycerols
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Fats
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Liquid triacylglycerols
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Oils
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Primary storage form of lipids
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Triacylglycerols known as body fat
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Triacylglycerols are __ soluable in water than fatty acids.
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less
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Why are triacylglycerols less soluable in water than fatty acids?
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Lack of charged carboxylate group.
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Fats and oils are __ dense than water.
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less
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Why do fatty acids carry more energy per carbon than polysaccharides?
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They are more reduced.
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Why do fatty acids carry less water per gram than polysaccharides?
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Because they are nonpolar.
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Glucose and glycogen are for __ energy needs.
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short-term
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Fats are for __ energy needs.
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long-term
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A kind of body tissue containing stored fat that serves as a source of energy
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Adipose tissue
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Esters of saturated fatty acids and long chain alcohol.
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Waxes
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Types of fatty acids are insoluble and have high melting points.
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Waxes
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5 Functions of Waxes
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1. Storage of metabolic fuel in plankton 2. Protection and pliability for hair and skin in vertebrates 3. Waterproofing of feathers 4. Protection from evaporation in plants 5. Used by people in lotions, ointments, and polishes
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___contain polar head groups and nonpolar tails (usually attached fatty acids)
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Lipid membranes
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Properties of lipid membrane head groups determine __.
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the surface properties of membranes.
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Different organisms, as well as different tissues, have different __.
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Membrane lipid head group compositions
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At what pH would a glycerophospholipid be charged?
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Physiological pH
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____ are composed of two fatty acid forming ester linkages with the first and second groups of L-glycerol-3-phosphate.
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Glycerophospholipids
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Glycerophospholipids are commonly found connected to which carbon?
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C2
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Substituent groups of glycerophospholipids are called __.
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Head groups
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How are head groups of glycerophospholipids formed?
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When the highly polar phosphate group is further esterfied by an alcohol on the non-fatty acid side (R-group) of the phosphate group.
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The major component of most eukaryotic cell membranes.
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Phosphatidylcholine
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Prokaryotes, including E. coli, can't synthesize this lipid.
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Phosphatidylcholine
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Ether lipid common in vertebrate heart tissue. It's a vinyl ether analog of phosphatidylethanolamine.
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Plasmalogen
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First signaling lipid to be identified after acetic acid has esterfied. Aliphatic ether analog of phosphatidylcholine.
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Ether Lipid: Platelet-Activating Factor
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Long chain amino alcohol (sphingolipid backbone).
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Sphingosine
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How are fatty acids joined to sphingosine?
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Amide linkage
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Polar head group of a sphingolipid is connected to a sphigosine by a(n) __ or __ linkage?
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glycosidic or phosphodiester
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Referred to as lipid rafts and play roles in cell recognition.
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Sphingolipids
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Abundant in myelin sheath that surrounds some nerve cells in animals.
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Sphingomyelin
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What's the difference between sphingomyelin and phosphatidylcholine?
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There are two cis double bonds on a fatty acid chain in phosphatidylcholine, where sphingomyelin has no double bonds (is saturated) on the hydrocarbon chains.
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The main constituents of membranes.
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Phospholipids.
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Both a membrane lipid and precursor for steroid hormones.
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Cholesterol
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The blood groups are determined in part by the __.
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type of sugars located on the head groups in glycosphingolipids
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Structure of sugar is determined by an expression of specific __.
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glycosyltransferases
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Individuals w/ a glycosyltransferase that transfers a(n) ___ have A blood group.
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acetylgalactosamine group
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Individuals with a glycosyltranferase that transfers a(n) ___ have B blood group.
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galactose group
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type of lipid containing a 4-ring carbon structure and a hydroxyl group (polar head) in the A-ring with any of a variety of side chains attached.
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Sterol
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The steroid nucleus is __.
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almost planar
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Physiological Role of Sterols
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Present in membranes of most eukaryotic cells to modulate fluidity and permeability and thicken plasma membrane.
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Cholesterol is an example of a(n) __.
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Sterol
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Most bacteria lack __.
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sterols
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How do mammals obtain cholesterol?
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from food or synthesize it de novo (a new) in the liver.
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Cholesterol bound to __ is transported to tissues via __.
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proteins/blood vessles
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Many hormones are derivatives of __.
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sterols
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Steroids are ___ derivatives of sterols.
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oxidized.
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Steroids are __ polar than cholesterol.
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more
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Steroids are synthesized from __ in the __ and __.
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cholesterol/gonads/adrenal glands
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Many steroid hormones are male and female __.
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sex hormones.
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Bio-active lipids are present in __ amounts than storage or structural lipids.
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much smaller
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Biologically active lipids play vital roles as ___.
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signaling molecules between nearby cells.
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4 Lipid soluble vitamins.
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A,D,E, K
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How does enzymatic oxidation of arachidonic acid act as a signaling lipid?
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It yields: Prostaglandins (inflammation/fever) Thromboxanes (blood clots) Leukotrienes (smooth muscle contraction in lungs)
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Vitamin D regulates __.
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calcium uptake
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Involved in visual pigment.
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Vitamin A (Retinol)
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Precursor for other hormones involved in signaling.
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Vitamin D
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Antioxidant examples
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Vitamin E, K, and other lipid quinones
