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Transcript
summary osmosis : movement of water from lower solute concentration ( higher water concentration )to higher solute concentration (lower water concentraion ) why hypotonic cause hemolysis of RBCs (red blood cells ) ? hypotonic: it means lower concentration of solute around the cell, which mean the amount of higher ---> so water transport to the cell and the cell swell . this is not the only way cause hemolysis . hypertonic : concentration of solute inside the cell is lower than cytosol (outside ) (it mean higher concentration of water ) ---> so the water go outside and the cell shrink . such shrinking of cells that called crenation Active transport _ transport that need energy to transport molecule against its concentration gradient , energy obtained come from hydrolysis of adenosine tri phosphate (ATP) ---> that we called primary active transport Active transport divided into : 1- primary active transport(using energy directly) 2- secondary active trasport (using of energy indirectly ) primary active transport : use hydrolysis of ATPase a source of energy , this will cause change the shape of certain carrier protein (most common integral protein) (pumps , because it will pump certain ion into and out of the cell )---> pumps called sodium -potassium ATPase , why we called sodium potassium ? because it is selective to Na and K ,,, why we called ATPase ? parts of protein (enzyme ) that hydrolyze ATP . this hydrolysis of ATP will cause conformational changes for this protein , and it will expel Na ---> expel 3 ions of sodium out of the cell , and allow to entry 2 ions of potassium inside the cell . net ion equal 1 out of the cell . So inside the cell the charge will be negative . ATP that we use to phosphorylate the pump ,how? ( يعني الفكرة انو االرتباط بسببhydrolysis for ATP and phosphorylate for the pump this expel sodium out of the cell and it will allowed to entry of 2ions of potassium ,,,this what we called sodium potassium ATPase . - Note that the hydrolysis happened from binding of integral protein since we name it ATPase (pumps) - Difference between channels and pumps ? - Channel may be gated or not , It allow the entry of material ( down it concentration gradient ) ( passive transport) - Pumps : push something against it concentration gradient(active transport) - what makes membrane potential ? 1- negative ions inside the cell 2- Sodium -potassium pump Secondary active transport : : وصار في انه تم وضع ايونات الصوديم خارج الخيه وتركزت بالخارج طيب: فكرتها Concentration and Electrical gradient this energy converted to another state ( energy of motion ) stored energy converted to kinetic energy and use to transport other substances So this energy we use as source of potential energy is concentrated in Na So Sodium ions have this potential energy and this will be use as we mentioned movement of another ions against its concentration gradient . ATP الصوديم تخزنت بداخله طاقة جايه من: يعني- " :P اذا ً هذه الطاقه ال تنفذ (( مثل ما بتعرفو بقانون حفظ الطاقة ))" اللي جننونا فيه ايام المدرسهindirect وهي بيحكو عنهاSecondary رح استعملها بشكل غير مباشر عشان هيك اسمهاdown it's concentration gradient طبعا ُ انتقال الصوديم يكون)against) وانتقال االيونات رح يضطر يستخدم هاي الطاقةagainst ألنه اذا الصوديوم رح ينتقل- So it will leak back in the cell and take with it ions ( against it's concentration )(I mean against ions concentration gradient ) - Na concentrated outside the cell it’s go down its concentration gradient (passive) , So it doesn't need energy . I can use energy to do Job It can transport another ions against its concentration gradient , this ions can be Calcium ions ; for Example ( Calcium out more ) its enter the cell against its concentration gradient, how can this happened ? by using potential energy stored in Na ions this is secondary use energy indirectly . يعني انت بتأثر بطاقة على البكرة (انو بتسحبها) من,,, فكرة الموضوع مثال ممكن نشبهها بالبكرة ( ,,, جهة و ازا كان مثال في صندوق عالجهة التانية بيرتفعAntiporters( بس يا جماعة ما حدا يفهم انو الprimary , ,, والsecondary يصيرو كل واحد لحال ال همي التنين بيحدثو بنفس الوقت - secondary active transport can be Antiporters :moving two substances in opposite direction across the membrane . Symporters :of these transport move two substances in the same direction . - The concentration of Ca+2 is low in the cytosol because Na+ / Ca+2 Antipater's eject calcium ions . - Na+/ H+ Antiporters help to regulate the cytosol's PH by expelling excess H+ . - By contrast , dietary glucose and amino acids are absorbed into cells that line the small intestine by Na+/glucose and Na+/amino acid Symporters . Transport in vesicles : - Way to transport inside the cell , needs ATP , from one organelle to another , or one structure to another or from inside to outside or from Extracellular fluid to inside the cell. - which mean by = Endocytosis into the cell . = Exoctosis outside the cell . Endocytosis : material move into the cell بنجمعهم وبدخلهم كلهم مع بعض - There are three type of endocytosis 1- Receptor mediated endocytosis 2- Phagocytosis 3- Bulk -phase endocytosis - Receptor mediated endocytosis : highly selective , cells take up , specific ligands bind to specific Receptor. * Receptor protein in the plasma membrane recognise and binds to particular in ECF (Extracellular fluid ), for instance cells take up cholesterol containing low density of lipoproteins LDLs , tranferin (an-iron trans porting proteins (in the blood ) ,some vitamins , antibodies ,and certain hormones. - Lipoprotein (Lipid + protein) LDL -LDL : molecules that has low density lipoprotein we called transporter . -main function carry cholesterol so I have this molecules with all cholesterol it has transporter in the plasma then to cell . How cell take this cholesterol By endocytosis Receptor-mediated endocytosis of LDLs (and other ligands) occurs as follows (Figure 3.12): 1- Binding. On the extracellular side of the plasma membrane, an LDL particle that contains cholesterol binds to a specific receptor in the plasma membrane to form a receptor–LDL complex. The receptors are integral membrane proteins that are concentrated in regions of the plasma membrane called clathrin-coated pits. Here, a protein called clathrin attaches to the membrane on its cytoplasmic side. Many clathrin molecules come together, forming a basketlike structure around the receptor–LDL complexes that causes the membrane to invaginate (fold inward). 2-Vesicle formation. The invaginated edges of the membrane around the clathrin-coated pit fuse, and a small piece of the membrane pinches off. The resulting vesicle, known as a clathrin-coated vesicle, contains the receptor–LDL complexes. 3- Uncoating. Almost immediately after it is formed, the clathrin-coated vesicle loses its clathrin coat to become an uncoated vesicle. Clathrin molecules either return to the inner surface of the plasma membrane or help form coats on other vesicles inside the cell. 4-Fusion with endosome. The uncoated vesicle quickly fuses with a vesicle known as an endosome. Within an endosome, the LDL particles separate from their receptors. 5-Recycling of receptors to plasma membrane. Most of the receptors accumulate in elongated protrusions of the endosome. These pinch off, forming transport vesicles that return the receptors to the plasma membrane. An LDL receptor is returned to the plasma membrane about 10 minutes after it enters a cell. 6-Degradation in lysosomes. Other transport vesicles, which contain the LDL particles, bud off the endosome and soon fuse with a lysosome. Lysosomes contain many digestive enzymes. Certain enzymes break down the large protein and lipid molecules of the LDL particle into amino acids, fatty acids, and cholesterol. These smaller molecules then leave the lysosome. The cell uses cholesterol for rebuilding its membranes and for synthesis of steroids, such as estrogen. Fatty acids and amino acids can be used for ATP production or to build other molecules needed by the cell. بمستقبالت خاصه به علىCholesterol المحمل بالLDL يعني أي شي برتبطReceptor LDL Complex يكون Plasma membrane هاي المنطقة بتكون membrane هأل هاي المستقبلة بتكون مركزة على منطقة معينة من Pits ويوجد بروتين مركز بهاي المنطقة ورح يشكلو اشي مثلmembrane الجزء الداخلي من Clathrin-coated pits اسمهplasma membrane في ال Receptor LDL فبتكون اشي مثل السلة حول هاي البروتينات بتجمع على بعضها invaginated وو بسبب للغشاء Complex وهالClathrin بتكون مخاطة من الخارج بvesicles هاي الvesicles بعدين بكون un coated other vesicles عشان تعمل رح تروح كمان كمان مرةClathrin معfusion بصير لهاvesicles هاي الuncoated vesicles هيك بصير عنا Receptor هأل الReceptor بتنفصل عنLDL particles بعدينendosome(vesicles ) ) (نتوءاتprotrusions بتجمع وبتعملReceptor معظم هايplasma membrane لل ورح تروحvesicles وبتشكل كمانendosome فهاي النتوءات بتفصلendosome في . min 01 ُ ويحكيلك انو هاد االشي كثير سريع تقريبا membrane على ) عنbud off ( بتشكل زي برعم خارجيLDL اللي تحتوي علىtransport vesicle هال ال بكونDegredation بعدين بصيرlysosome وبعدين ترتبط معendosome ال lysosome وبعدها بتغادرالamino acids , fatty acids , cholesterol phagocytosis : cell engulfs large solid particle only a few body cells termed phagocytosis ..especially digestive cells two main type of phagocytosis cell 1- macrophage 2- neutrophils - phagocytosis begin when particles bind to plasma membrane Receptor on the phagocyte causing it to extend Pseudo pods . * Pseudo pods surround the particle outside the cell and membrane fuse to form vesicle called a phagosome Which enter the cytoplasm * How phagocytosis occurs? - The phagosome fuse with one or more lysosomes , and lysosomal enzymes break down ingestion and remain in vesicle called a residual Body . - The process of phagocytosis is a vital defense mechanism that helps protect the body from disease . - Through phagocytosis macrophages dispose of invading microbes and billions of aged , warn out red blood cells every day , neutrophils also help rid the body from invading microbes pus is a mixture of dead neutrophils an infected wound - Bulk- phase endocytosis , also called pinocytosis ECF contain a lot of bulk tiny droplet of ECF will taken up , Note that No receptor involved it's not selective , all solutes dissolved in the ECF are brought into cell . - During bulk -phase endocytosis the plasma membrane folds inward and form a vesicle detaches or " pinches off " from the plasma membrane and enters the cytosol , which in the cell the vesicle fuses with a lysosomes where enzymedegrade the engulfed solutes The resulting smaller molecules , such as amino acids and fatty acids , leave the lysosome to be used elsewhere in the cell . Bulk-phase endocytosis occurs in most cells , especially absorptive cell in the intestine and kidneys . Exocytosis - Exocytosis it release material from a cell . -All cells carry out exyctosis especially 1- secretary cells , 2-nerve cell release substance that called neurotransmitters (we will studied later ) - secretary cells : liberate digestive enzymes hormones , mucus ,or other secretion . wastes are also released by Exocytosis - There must be balance between Exocytosis and endocytosis why ? to keep the surface area of cell's plasma membrane relatively constant segments of plasma membrane . Lost through endocytosis and recycled by exocytosis - Membrane exchange is quit extensive in certain cells that . In pencrease for Example the cells that secrete digestive enzymes can recycle an amount of plasma membrane equal to the cell's entire surface area in 90 minute ( Balance) Trascytosis TRANSCYTOSIS Transport in vesicles may also be used to successively move a substance into, across, and out of a cell. In this active process, called transcytosis, vesicles undergo endocytosis on one side of a cell, move across the cell, and then undergo exocytosis on the opposite side. As the vesicles fuse with the plasma membrane, the vesicular contents are released into the extracellular fluid. Transcytosis occurs most often across the endothelial cells that line blood vessels and is a means for materials to move between blood plasma and interstitial fluid. For instance, when a woman is pregnant, some of her antibodies cross the placenta into the fetal circulation via transcytosis و االختالف بهاي,,, كل االغشية بتتشابه بكب شي تقريبا اال البروتينات اللي بتحتويها البروتينات هوالمسؤول عن االختالف بالوظيفة Good luck^^