浙大生态学电子课件复习9.lipid

1、10. Li.5.sBiological functions of LisStructure and functions otty acids (triacylglycerols and waxes)Structures and functions of three Types of Membrane Lis (exles).Three subclasses of sphingolis and Tay-Sachs diseaseLis presentuch smaller amounts and play active roleshe metabolic traffic asme

2、tabolites and messengers (exles ofracellular signals messages to nearby cells,messages betn ties, hormone precursors cofactors and activate sugar precursors).The biological functions of the lis（emphsize）考点1.2.3.Energy storage (fats anls)Major structural elements of biological membrane (phospholis an

3、d sterols).Others (enzyme cofactors, light-absorbing pigments（色素）, hormone, electron carrier)* Storage Lis Fatty Acids;The fatty acids are hydrocarbon derivatives, at about the same low oxidation or highreduction se as the hydrocarbons in fossil fuels. The cellular oxidation otty acids (toCO2 and H2

4、O), like the controlled, raburning of fossil fuels inernal combustionengines, is high exergonic（放出能的）. Fatty acids are straight-chain acids of carbon atoms,whiay be saturated or unsaturated.注意常见脂肪酸的结构式及其特征Two Types oty Acids（emphsize）Structure and functions o1. Triacylglycerolstty acids (triacylglyc

5、erols and waxes)（考点）Triacylglycerols Are Fatty Acid Esters of GlycerolThe simplest lis constructed from fatty acids are the triacylglycerols, are comed ofty acids each in ester linkage wisingle glycerol. Simple triacylglycerols of 16:0,18:0, and 18: l, for exle, are tristearin 硬脂酸甘油酯, tripalmitin 软脂

6、酸甘油酯, andtriolein 油酸脂, respectively.Triacylglycerols Provide Stored Energy and Insulation （绝缘）As stored fuels, triacylglycerols have two significant advantages ovolysaccharidech as glycogen and starch.1.The carbon atoms of fatty acids are more reducedn those of sugars, andoxidation of triacylglycero

7、ls yields moren twice as much energy, gram fram,ast of carbohydrates.2.Furthermore, because triacylglycerols are hydrophobic and therefore unhydrated未水合的, theanismt carries fat as fuel does not have to carry the extraweight of water of hydration 水 合 作 用polysaccharides.t is assoted with storedTriacyl

8、glycerols stored under skin serve not only as energy stores but as insulation against low temperatures2. WaxesWaxes Serve as Energy Stores and Water Repellents 排斥的Biological waxes are esters of long-chain saturated and unsaturated fatty acids (having 14 to 36 carbon atoms) with long-chain alcohols (

9、having 16 to 30 carbon atoms). Their meltingpos (60 to 100 C) are generally highern those of triacylglycerols.Major Functions of Waxes;1.Chief storage form of metabolic fuel.Water-repellent (on feather) and theirfirm consistency (beeswax)2.3.* Structural LisembranesThree general types of membrane li

10、s:Structures and functions of three Types of Membrane Lis (exles).考点1.Glycerophospholis 磷酸甘油脂,Phosphatidic Acid ，are membrane liGlycerophospholis Are Derivatives ofs in which two fatty acids are attached inester linkage to theand second carbons of glycerol, and a highly polar orcharged group is atta

11、ched through a phosphodiester linkage to the third carbon.Some PhospholiSome animal tis Have Ether 醚-Linked Fatty Acids 其中的结构特例es and some unicellular 单细胞的anisms are rich in ether lis, inwhich one of the two acyl chains is attached to glycerol in ether, rathern ester, linkage.2.Sphingolis 鞘脂类, Sphin

12、golis Are Derivatives of Sphingosine 。are comedof one molecule of the long-chain amino alcohol sphingosine, one molecule of along-chain fatty acid, a polar head alcohol, and sometimes phosphoric acid in diester linkage at the polar head group.Three subclasses of sphingolis;考点(all derivatives of cera

13、mide 神经酰胺, but differing1.Sphingomyelins 鞘磷脂 areheir head groups)glycerophospholis.presentinplasma血 浆membranes of animal cells; the myelin 髓磷脂 sheath 鞘 which surrounds and insulates the axons 突触 ofmyelinated 有髓鞘的 neuronsisagoodsourceofsphingomyelins.Sphingomyelinscontainphosphocholine 胆 碱 磷 脂orphosp

14、hoe their polar thereforephospholinolamine 胆胺磷脂 ashead group, and areclassifiedtogetheraswiths,2. Glycosphingolis 鞘糖脂 The sugar-containing sphingolis are calledglycosphingolimembrane.s. These glycosphingolis occur largely in the outer face of the plasmaSphingolis Are Sites of Biological RecognitionT

15、he human blood groups (O, A, B) are determined in part by the sugar headgroupshese glycosphingolis. The same three types of complex sugar groups are alsofound attached to certain blood proteins of individuals of blood types O, A, and B,respectively.3. Gangliosides 神经节苷脂 the most complex sphingolis,

16、contain very largepolar heads made up of several sugar units. Gangliosides make up about 6% of themembrane lis in the gray matter of the human brain, and they are present inlesser amountshe membranes of most nonneural animal ties.考点例 Tay-Sachs disease, a specific ganglioside accumulates in the brain

17、 and spleen 脾 due to the lack of the lysosomal 神经元体细胞的 enzyme hexosaminidaseA. As a result, the partially degraded gangliosides accumulate, causing degenerationof the nervous system. The symptoms of Tay-Sachs disease are progressiveretardation in development, paralysis, blindness, and death byof 33.

18、Sterols, compounds characterized by a rigid system of four fused hydrocarbon rings.Sterols are structural lis consisting offour fused rings, three with six carbons andith five. Cholesterol 胆固醇, the majorsterol in animal ties, ishipathic, a nonpolarlong as awith a polar head group andhydrocarbon body

19、 about as16-carbon fatty acid in its extended form.The sterols serve as precursors for a varietyofproductswithspecificbiologicalactivities. Bile acids, and variety of steroid hormones are produced from cholesterol byoxidation of the side chain at C-17.* Lis as Signals, Cofactors, and Pigments 考点：概况，

20、实例Lis present in much smaller amounts, have active roles in the metabolic traffic asmetabolites and messengers.1.Some serve as potent signals, as hormones carriedhe blood from one tie toanother, or asracellular messengers generated in response to an extracellularsignal (hormonerowth factor).2.Others

21、 function as enzyme cofactors in electron-transfer reactions in chloroplastsand mitochondria, or糖基化 reactions.lis with a system of t absorb visible light.les：Phosphatidylinositols (he transfer of sugar moieties in a variety of glycosylation3.conjugated 共轭的 double bonds: pigment 色素 moleculesEx1.2.rac

22、ellular Signals)Eicosanoids (Messages to nearby Cells)：Eicosanoids Are Potent Biological EffectorsThree classes of eicosanoids:1.prostaglandins素,The prostaglandins (PG) contain a five-membered ring of carbon atoms originally partof the chain of arachidonic acid. They derive their name from the tie i

23、n which theywererecognized (the prose gland).Major function; Some prostaglandins stimulate contraction of the smooth muscle of theuterus during labor or menstruation. Others affect blood flow to specificans, thewake-sleep cycle, and the responsiveness of certain ties to hormones such asnephrine and

24、glucagon. Prostaglandins in a third group elevate body temperature(producing fever) and cause inflammation, resulting in pain.2.thromboxanes,isolated from blood plaets (also known as thrombocytes),have a six-membered ring containing an ether. They are produced by plaets andact in formation of blood

25、clots and the reduction of blood flow to the site of a clot.3.leukotrienes. foundin leukocytes, contain three conjugated double bonds.They areerful biological signals; for exle, they induce contraction of theroduction of leukotrienes causesmuscle lining the airways to theg. Ovasthmatic attacks. The

26、strong contraction of the smooth muscles of thegtoccurs during anaphylactic shock is part of the potentially fatal allergic reaction inindividuals hypersensitive to bee stings, penicillin, or various other agents.3.Steroids (Messages betn Ties)Steroids derived from cholesterol（胆固醇）:Testosterone激素, t

27、he male sexhormone, is produced Estradiol 雌二醇, one hormones, is producedand placenta.he testes.of the female in the ovariesCortisol 皮质醇and aldosterone 醛固醇are hormones producedhe cortex ofthe adrenal gland; they regulate glucosemetabolismrespectively.andsaltexcretion,4. Vitamins A and D (Hormone Prec

28、ursors)Vitamins: The compoundst are essential to the health of humans and othervertebrates bthe diet.annot be synthesized by these animals and must be therefore be obtained inVitamins A and D Are Hormone PrecursorsVitamin A (retinol) is a pigment essential to vi. Deficiency of vitamin A leads to ava

29、riety of symptoms in humans, which include dry skin, dry eyes, membranes, retarded 智力迟钝 development and growth, sterility 中性 blindness.Fish liver oils, eggs, whole milk are good vitamin A dietary sourdry mucous 粘ale, and night. Carrots, stpooes and other yellow vegetables contain rich carotene, a pr

30、ecursor of vitamin AVitamin D (cholecalciferol) is a derivative of cholesterol and the precursor to a hormoneessential in calcium and phosphate metabolism in vertebrate animals. Vitamin D3 itself isnot biologically active, but it is the precursor of 1,25-dihydroxycholecalciferol, a potenthormonet re

31、gulates the uptake of calcium in theestine的 and the balance ofrelease and deition of bone calcium and phosphate. Vitamin D3 is normally formedheskin in a photochemical 光化学的 reaction driven by the ultraviolet 紫外线 component ofsunlight. It is also abundant in fish liver oils, and is added to commerl mi

32、lk as anutritional supplement.5. Vitamins E and K (Cofactors Cofactors)Vitamin E is the collective name for a group of closely related lis called tocopherols 生育酚, all of which contain a substituted aromatic ring 芳香取代基 and a longhydrocarbon side chain. Tocopherols are found in hens eggs and vegetable

33、 oils, and areespelly abundant in wheat germ. Deficiency of vitamin E is very rare in humans, butwhen laboratory animals are fed diets depleted of vitamin E, they develop scaly 劣质的skin, muscular weakness and wasting, and sterility 不育.Vitamin K is a licofactor required for normal blood clotting. Vita

34、min Kl is found ingreen plant leaves, and a related form, vitamin K2 is formed by bacteria residingheanimalestine.The vitamin K actshe formation of prothrombin, a blood plasma protein essential inblood-clot formation. Deficiency of vitamin K results in slowed blood clotting, which canbe fatal to a wounded animals.6. Dolichols (Activate Sugar Precursors)Dolichols; derived from four or more linked isoprene units. These compounds have stronghydrophobiceractions with membrane li, anchoring the attached sugars to themembrane where they participate in sugar-transfer reactions.* Separation andy