![Active transport
Uses energy from ATP to move molecules
against concentration gradient
Moves from [lower] → [higher]
Uses protein pumps
OR
vesicles
Animations from:
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/cell-movement.html
http://www.cat.cc.md.us/courses/bio141/lecguide/unit1/eustruct/images/sppump.gif](https://image.slidesharecdn.com/cellmembranerassbiosolution-130610010409-phpapp02/85/Cell-membrane_rass-biosolution-29-320.jpg)
Cell membrane_rass biosolution
- 1. RASS-BIOSOLUTION PVT LTD www.rass-biosolution.com Email:sk@rass-biosolution.com Contact: +91-7897016047
- 3. Membranes provide a variety of cell functions
- 4. Fluid Mosaic Model of the PM A membrane is a mosaic Proteins and other molecules are embedded in a framework of phospholipids A membrane is fluid Most protein and phospholipid molecules can move laterally
- 5. Embedded in the bilayer are proteins Most of the membrane’s functions are accomplished by the embedded proteins. • Integral proteins span the membrane • Peripheral proteins are on one side or the other of the membrane
- 6. HYDROPHILIC/HYDROPHOBIC areas determine positions of molecules in cell membranes hydrophobic amino acids stick in the lipid membrane anchors the protein in membrane hydrophilic amino acids stick out in the watery fluid in or out of cell
- 7. Plasma Membrane Components Glycoproteins and glycolipids are proteins/lipids with short chain carbohydrates attached on the extracellular side of the membrane.
- 8. Fig. 5-1a Cholesterol Glycoprotein Glycolipid Carbohydrate of glycoprotein Phospholipid Microfilaments of cytoskeleton Integrin
- 9. Types of Membrane Proteins 1. Cell-cell recognition proteins 2. Integrins 3. Intercellular junction proteins 4. Enzymes 5. Signal transduction protein 6. Transport proteins – Passive and active
- 10. Transport Proteins Passive Transport Proteins allow water soluble substances (small polar molecules and ions) to pass through the membrane without any energy cost Active Transport Proteins The cell expends energy to transport water soluble substances against their concentration gradient
- 11. Fig. 5-1d
- 12. Molecules need to move across membranes in cells Image modiified from: http://www.accessexcellence.org/AB/GG/importProt.html IN food carbohydrates sugars, proteins amino acids lipids salts, O2, H2O OUT waste ammonia salts CO2 H2O products
- 14. Transport of Substances Across the Plasma Membrane 1. Passive Transport Simple Diffusion Facilitated diffusion Osmosis 2. Active Transport 3) Bulk Flow Endocytosis Exocytosis
- 15. Passive Transport In passive transport substances cross the membrane by diffusion Diffusion - net movement of substances from an area of high concentration to low concentration • no energy required
- 16. Factors Affecting Diffusion Rate Steepness of concentration gradient Steeper gradient, faster diffusion Molecular size Smaller molecules, faster diffusion Temperature Higher temperature, faster diffusion
- 17. http://www.le.ac.uk/pa/teach/va/anatomy/case2/2_2.html Example: DIFFUSION IN CELLS O2 automatically moves from HIGHER concentration (in lungs) to LOWER concentration (in blood) CO2 automatically moves from HIGHER concentration (in blood) to LOWER concentration (in lungs) http://facstaff.bloomu.edu/gdavis/links%20100.htm
- 18. Facilitated diffusion Move from HIGH to LOW concentration with aid of membrane transport proteins passive transport no energy needed facilitated = with help
- 19. Facilitated Diffusion Passive transport protein Lower concentration Higher concentration of
- 20. 1. Facilitated diffusion via a glucose transporter outside inside glucose MECHANISMS OF GLUCOSE TRANSPORT INTO A CELL
- 21. Glucose transporter GLUT1 RBc GLUT2 liver and pancreas GLUT4 muscle GLUT5 fructose
- 22. Osmosis Osmosis – diffusion of water across a selectively permeable membrane Water moves from an area of _______ water concentration to an area of _____ water conc. Is energy required ? Water travels in/out of the cell through aquaporins
- 23. Osmosis Terms Consider two solutions separated by a plasma membrane. Hypertonic solution with a relatively high concentration of solute Hypotonic solution with a relatively low concentration of solute Isotonic solutions with the same solute concentration
- 24. Water molecule Selectively permeable membrane Solute molecule H2O Lower concentration of solute Higher concentration of solute Equal concentration of solute Solute molecule with cluster of water molecules Net flow of water
- 25. Osmosis and Animal Cells
- 26. Osmosis and Plant Cells
- 27. Aquaporins Proteins embedded in the cell membrane that regulate the flow of water. Integral membrane proteins from a larger family of major intrinsic proteins (MIP) that form pores in the membrane of biological cells.
- 28. 4 monomer associated in a tetramer. Each monomer forms a transmembrane pore for water to pass. Each monomer-6 helices and 2 short helices-contain Asn- Pro-Ala repeats. Repeats extend inside the bi-layer, overlap with each other forming specificity filter.
- 29. Active transport Uses energy from ATP to move molecules against concentration gradient Moves from [lower] → [higher] Uses protein pumps OR vesicles Animations from: http://academic.brooklyn.cuny.edu/biology/bio4fv/page/cell-movement.html http://www.cat.cc.md.us/courses/bio141/lecguide/unit1/eustruct/images/sppump.gif
- 31. Fig. 5-8-2 Transport protein Solute Solute binding1 Phosphorylation2
- 32. Fig. 5-8-3 Transport protein Solute Solute binding1 Phosphorylation2 Transport3 Protein changes shape
- 33. Fig. 5-8-4 Transport protein Solute Solute binding1 Phosphorylation2 Transport3 Protein changes shape Protein reversion4 Phosphate detaches
- 34. Active Transport tell the story… ATP P ADP
- 35. Four classes of ATP-driven pumps
- 37. Primary Active Transport Na+-K+ Pump, ATPase (P-type pump)
- 38. Cycles of Na+-K+ Pump
- 42. Na+-Glucose Transporter: Cooperative binding of Na+ and glucose to the carrier. Kidney tubules and intestine, for re-absorption of glucose. Na+ moves down its electrochemical gradient, glucose moves up. Secondary Active Transport
- 43. 3 types of carrier-mediated transport Coupled carriers
- 44. Ion Channels Features: •They have high rates of fluxes •Are not saturable. •They are “gated” -they open or close in response to some cellular signal. •Provide hydrophilic pore
- 45. The Gating of Ion Channels
- 46. The Structure of bacterial K+ channel Selectivity filter-allows K+ (0.133nm) to pass10,000 fold more readily than Na+ (0.095 nm)
- 47. Gating Model of K+ channel • Consists of 4 identical subunits. • Each subunit -2 transmembrane helices+1 short helix=pore region • Carbonyl oxygen bind to K+ and not Na+ - ”preferential stabilization”
- 48. Carrier Proteins Channel Proteins •Monomeric •High Specificity •Saturable •Low rates of transport •Oligomeric •Low Specificity •Not Saturable •High rates of Transport
- 49. Ionophores can serve as channels and carriers for ions
- 50. Bulk Flow Vesicles are used to transport large particles across the PM. Requires energy Types: Exocytosis Endocytosis • Phagocytosis, pinocytosis, receptor-mediated
- 52. Bulk Flow Exocytosis Cytoplasmic vesicle merges with the PM and releases its contents Example: • Golgi body vesicles merge with the PM an release their contents • How nerve cells release neurotransmittors
- 53. Vesicle forming Endocytosis Endocytosis can occur in three ways • Phagocytosis ("cell eating") • Pinocytosis ("cell drinking") • Receptor-mediated endocytosis
- 54. Endocytosis Endocytosis PM sinks inward, pinches off and forms a vesicle Vesicle often merges with Golgi for processing and sorting of its contents
- 55. Endocytosis - terms Phagocytosis – cell eating Membrane sinks in and captures solid particles for transport into the cell Examples: • Solid particles often include: bacteria, cell debris, or food Pinocytosis – cell drinking Cell brings in a liquid
- 56. Endocytosis - comments Phagocytosis and pinocytosis are not selective Membrane sinks inward and captures whatever particles/fluid present. Vesicle forms and merges with the Golgi body…
- 57. Receptor Mediated Endocytosis Receptor Mediated Endocytosis is a highly specific form of endocytosis. Receptor proteins on the outside of the cell bind specific substances and bring them into the cell by endocytosis
- 58. Receptor Mediated Endocytosis 1. Receptor proteins on PM bind specific substances (vitamins, hormones..) 2. Membrane sinks in and forms a pit – Called a coated pit 3. Pit pinches closed to form a vesicle around bound substances • Cytoskeleton aids in pulling in the membrane and vesicle formation
- 59. Fig. 5-9c Coated vesicle Coated pit Specific molecule Receptor-mediated endocytosis Coat protein Receptor Coated pit Material bound to receptor proteins Plasma membrane
- 61. Fig. 5-9 Phagocytosis EXTRACELLULAR FLUID Pseudopodium CYTOPLASM Food vacuole “Food” or other particle Pinocytosis Plasma membrane Vesicle Coated vesicle Coated pit Specific molecule Receptor-mediated endocytosis Coat protein Receptor Coated pit Material bound to receptor proteins Plasma membrane Food being ingested