76

Biochemie (Fach) / Lipide (Lektion)

Diese Lektion wurde von violetta91 erstellt.

Lektion lernen

Diese Lektion ist leider nicht zum lernen freigegeben.

zurück  |  weiter 2 / 2

• Thermal transition Lß Thermal transition from the gel phase Lβ to the liquid crystalline phase Lαin a pure PC bilayer. At low temperatures, motion of the fatty acids islimited by van der Waals forces. As the temperature rises through thephase transition, heat is absorbed and fatty acids are melted.
• Lipases are important enzymes for lipid signalling Phospholipase A2:Phospholipid → Lyso-Phospholipid + Free Fatty Acid PIP2-specific Phospholipase C:Phosphatidylionositol-bisphopshate (PIP2) → Inositoltrisphophate + Diacylglycerol Phospholipase A2:Phospholipid → Lyso-Phospholipid + Free Fatty Acid
• Phospholipase C Phospholipase C generates the second messengersInositoltrisphophate and diacylglycerol
• Provitamin A Provitamin A (β-Carotin) Aus Pflanzen - Spaltung im Menschen - Vitamin A (Retinol) The eye effect of retinalThe rods contain a pigment, rhodopsin, consisting of a specific protein(photopsin) bound to 11-cis retinol. In light, the 11-cis retinol isconverted to all-trans-retinal which dissociates from the protein. Theenergy generated results in closure of Na channels via decrease incyclic GMP.
• Vitamin A Functions in humans:retinal: the visual effect in the retina Avitaminose A: deficiency syndroms:increased mortallity during intercurrent infectionsdryness of the conjunctiva and the cornea (xerophthalmia), ulcerationand finally eye damage, may lead to blindness Particularly in southeast Asia, where rice is consumed which iscarotenoid free, xerophthalmia occurs.
• Function of carotenoids in plants: Photosynthesis Carotinoides are pigments that protect the proteins of photosynthesisagainst high light damage (e.c. Xanthophyll cycle) Carotinoides participate in photon collection and are constituents oflight harvesting complex II (LHCII)
• Sterol lipids Cholesterol is the most abundant sterol in animals  In plants, β-sitosterol and stigmasterol are predominent.
• Brassinosteroids: Plant steroid hormones Brassinosteroides 1960, isolated from rape pollen. Steroid phytohormones Derived from campesterol Function in plants:Stem elongationPollen tube growth Leaf inclination of monocots
• Cholesterol in human health Cholesterol:is a plasma membrane lipid: enhances membrane fluidity Transprot in the blood as lipid-protein paticles: chylomikrons, VLDL, IDL, LDL, HDL(high cholesterol --> coronary heart disease) precursor for bile acids in the bile bladder (Vorstufe von Gallensäuren in derGallenblase) precursor for vitamin D synthesis precursor for steroid hormones: cortisol, aldosterone, progesterone, estrogens,testosterone,...
• Vitamin D supplementation The photochemical synthesis of vitamin D was discovered by Adolf Windaus in 1927(Nobel price 1928) Commercial sources for provitamin D are derivedfrom cholesterol (-> provitamin D3)or from ergosterol (-> provitamin D2).Ergosterol is a fungal sterol that can be isolated from yeast, or obtained synthetically
• Anzeige
• Calcitriol is the active form of vitamin D Function in humans:Calcitriol is a steroid hormone in Ca homeostasis.Calcitriol is transported to distal tissues, enters the cells, binds to a receptor and is taken up into the nucleus. Here, it triggers mRNA transcription of proteins of Ca homeostasis.
• Deficiency (Mangel) in Vitamin D Rickets (Rachitis)In children, vitamin D deficiency results in rickets,skeletal deformity, bone pain and tenderness andmuscle weakness, furthermore osteomalacia and bonedemineralization due to deficiency in Ca deposition. X-Ray of bone deformation in a children suffering from rickets
• Glucocorticosteroids Steroid hormones of the adrenal cortex in the kidney Glucocorticoids (e.g. Corticosterone, cortisone, cortisol) control carbohydrate, fatand protein metabolism and are anti-inflammatory by preventing phsopholipidrelease, decreasing eosinophil action.Cortisone, an inactive form, is the oxidized form of cortisol carrying a keto insteadof a hydroxy group at C-11.Cortisol (=Hydrocortisone) is used as an anti-inflammatory drug
• Mineralocorticoids Steroid hormones of the adrenal cortex in the kidney Mineralocorticoids (e.g. Aldosterone) control electrolyte and water levels, mainlyby promoting sodium retention in the kidney. Aldosterone
• Androgenes Produced in testis and adrenal cortex Promote the establishment of male characteristics Testosteron
• Estrogenes Produced in ovary and adrenal cortex Promote the establishment of female characteristics
• Progestagenes Produced in ovary and placenta During pregnancy Progesteron
• Sterol degradation and bile acids Bile acids are produced in the liver by oxidation of cholesterol. They are conjugatedwith taurine or glycine, stored in the gallbladder and released into the intestine.Bile acid have detergent-like characteristics and are required for micel formationwith lipids from the diet, a prerequisite for lipid uptake from the gut. Cholesterol Cholic acid Taurocholic acid Furthermore, bile formation also represents a pathway for cholesterolcatabolism and excretion
• Prenyl quinone lipids (Prenylchinon Lipide) are composed of a quinone ring and a prenyl side chain electron carrier of PS II electron carrier of respiration structural component of photosystemsVitamin K1 Antioxidants in chloroplast membranesVitamin E
• Vitamin E: Tocopherol and Tocotrienol Side chain: Phytyl Double bonds - Side chain: geranylgeranyl Vegetable oils from dicot plantsRapeseed, sunflower, olive oil Vegetable oils from monocot plantsWheat germ oil, palm oil
• Vitamin E Metabolism in the human bodyTocopherol binding protein in the blood is very specific for α- tocopherol Function in humansStrong antioxidants, protects lipids from oxidation by reactive oxygen species Vitamin E deficiency:Severe vitamin E deficiency affects reproduction in males andfemales (rat fetal absorption assay)very rare, some heritable diseases (tocopherol binding proteindeficiency): (Selten in der entwickelten Welt) encephalomalacida, cerebellar ataxia, anaemia, fatigue Dry skin, wounds
• Vitamin K (Phylloquinone) Vitamin K: Function in humans Cofactor of glutamate carboxylation in proteins: Faktors of blood coagulation (Factor II/Prothrombin, VII, IX and X) Osteocalcin (Protein of bone formation) Vitamin K deficiency:Haemorrhagic diathesis (bleeding) (with infants): Vitamin K supplementation postnatal γ-carboxylation of gluatmate residues in mammalian proteins is catalyzedby vitamin K dependent carboxylases Carboxylation is essential for Ca binding of these proteins
• Vitamin K: Function in plants Phylloquinone is a redox carrier (Fx) in Photosystem I
• Plastoquinol, PQ, (deutsch: Plastochinol) Plastoquinol serves as one or two electron carrier Plastoquinone (PQ) is the electron carrier betweenPhotosystem II and the Cyt b6/f complex in photosynthesis
• Ubiquinone (Ubichinon, Coenzym Q) (n = 10 isoprenoid units) Ubiquinone, Coenzyme Q10 (deutsch: Ubichinon) Ubiquinone is a redox carrier in the mitochondrion of all eukaryotes Redox reactions of ubiquinone: Ubiquinone can carry one or two electrons
• Respiratory chain (Atmungskette) Mitochondrial electron transfer chain in the inner membrane

zurück  |  weiter 2 / 2