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32 Cards in this Set
- Front
- Back
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what is a phospholipid?
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any lipid that contains a phosphate group
Most of these lipids have a glycerol backbone |
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Is sphingosine a phospholipid?
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YES
it forms sphingomyelin has a sphingosine backbone It is a sphingolipid but it is also a phospholipid |
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what is a neutral lipid?
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Storage lipids
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what is a polar lipid?
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glycerophospholipids, glycolipids
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what is a complex lipid?
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lipid used to form membranes
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what is a simple lipid?
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lipid that is used for energy storage
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What is a phospholipid used for?
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1. key structural/functional membrane constituent
2. Precursor of 2nd messanger in signal transduction 3. Can provide fatty acyl energy |
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where are phospholipids predominately present?
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In MEMBRANES
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where are phospholipids synthesized?
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Endoplasmic reticulum
phospholipids need to be constantly replaced within the cell |
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Where do the fatty acids for phospholipids come from ?
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Fatty acids come from serum albumin, VLDL, Chylomicrons, as well as elongation and desaturation reactions within the cell
The fatty acid must be activated and a source of glycerol-3-phosphate is needed |
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What are the 6 glycerol backbone phospholipids?
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1. PS: phosphatidylserine
2. PC: phosphatidlycholine 3. PE: phosphatidylethanolamin 4. PI: phosphatidylinositol 5. PG: phosphatidylglycerol 6. DPG: diphosphatidylglycerol |
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what is the major fatty acid that is synthesized by humans?
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Palmitic acid
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what is the precursor for all lipids that have a glycerol backbone?
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Phosphatidic acid is used to form every lipid that has a glycerol backbone
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How is phosphatidic acid synthesized?
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Three major ways:
1. Major pathway: Use Glycerol kinase > glycerol-3-phosphate > add two activated fatty acids > phosphatidic acid 2. add an activated fatty acid to DHAP > reduce the product using NADPH > add another activated fatty acid > phosphatidic acid 3. reduce DHAP to Glycerol-3-phosphate using NADPH > phosphatidic acid |
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what is phospholipid remolding?
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the fatty acids in the membrane phospholipids can be swapped out to change the properties of the membrane on an as needed basis
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Describe an example of phospholipid remolding
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Dipalmitoyllecithin in lung tissue is formed using remodeling. Phosphlipase A2 removes the fatty acid in the 2 position and replaces it with Palmitic acid
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What 4 enzymes degrade glycerophospholipids?
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1. Phospholipase A2
2. Phospholipase A1 3. Phospholipase D 4. Phospholipase C |
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what does phospholipase A2 do?
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Remodeling and degradation + signal transduction
present in many mammalian tissues and pancreatic juice & in snake venom Acts on phosphtidylinositol > releases arachidionic acid (precursor to prostaglandins) Proenzyme Rich in pancreatic secretions > activated by trypsin and requires bile salts for activity |
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What does phospholipase A1 do?
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Remodeling and degradation
Present in many mammalian tissues |
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What does phospholipase D do?
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Degradation of enzyme > cleaves off the base and phosphate to produce a diglyceride
found in the liver lysosomes and the alpha-toxin of clostridia and other bacilli Membrane bound/acitivated by many hormones > plays a role in producing 2nd messengers |
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what 3 enzymes are involved in signal transduction?
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Phospholipase A2, C, and D play critical roles in allowing external signals to be transmitted into cells
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How does Phospholipase A2 act in signal transduction?
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releases fatty acids from the plasma membrane for eicosanoid synthesis
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how is Phospholipase C involved in signal transduction?
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cleaves phosphatidylinositol and other inositides in the plasma membrane to give diglycerides and inositol phosphates, especially inositol 1,4,5-triphosphate which promotes calcium release
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how is phospholipase D involved in signal transduction ?
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forms phosphatidic acid which is probably acting as a second messenger
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what is the chemical name for surfactant?
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Dipalmitoylphosphatidal choline
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what is RDS?
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Respiratory distress syndrome
-condition where oxygen cannot be absorbed into hemoglobin in the blood because the alveoli cannot stay open because they do NOT contain enough lung surfactant |
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how is DPPC formed in the lungs?
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formed by phospholipid remodeling (phospholipase A1 & A2 actions)
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how can a physician determine if the lungs of a baby are developed enough to deliver?
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take amniotic fluid sample to measure DPPC levels
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besides DPPC levels in the amniotic fluid what else can be measured to determine the maturity of the fetus before delivery?
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Lecithin/sphingomyelin ration in the amniotic fluid can also be used to determine the maturity of the lungs
Ratio of 2 indicates full maturity This is usually reached ~35 weeks gestation |
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how many babies born before 28 weeks of gestation usually develop RDS?
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60%
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how many babies born at 35 weeks of gestation or later usually develop RDS?
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5%
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what can be given in utero to speed up the maturation of the lungs?
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Corticosteriods
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