1 / 30

MEMBRANE TRANSPORT

MEMBRANE TRANSPORT. LECTURE-----4 DR ZAHOOR ALI SHAIKH. MEMBRANE TRASPORT. Plasma membrane is selectively permeable that means it allows some particles to pass while other can not pass. Things which can pass through Plasma membrane easily are:

tyra
Download Presentation

MEMBRANE TRANSPORT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MEMBRANE TRANSPORT LECTURE-----4 DR ZAHOOR ALI SHAIKH

  2. MEMBRANE TRASPORT • Plasma membrane is selectively permeable that means it allows some particles to pass while other can not pass. • Things which can pass through Plasma membrane easily are: 1. Lipid soluble particles e.g. O2, CO2, fatty acid. 2. Size of the particle—less than 0.8nm.

  3. MEMBRANE TRANSPORT(CONT) • Note – If particles are low lipid soluble and size more than 0.8nm, they can not pass. • MOVEMENT ACROSS CELL MEMBRANE • Two Types: 1. Passive transport– No energy is required 2. Active transport– energy is required

  4. MEMBRANE TRANSPORT(CONT) • DIFFUSION • If two solutions are separated by permeable membrane , the movement will take place from high concentration to low concentration That is down the Concentration Gradient also called CHEMICAL GRADIENT. • No energy is required for this movement • It is passive mechanism of Membrane Transport. • Example: O2 transferred across the Lung membrane is Diffusion.

  5. MEMBRANE TRANSPORT(CONT) DIFFUSION

  6. MEMBRANE TRANSPORT (CONT) • NET DIFFUSION It is the difference between Two opposite movement

  7. FACTORS INFLUENCING THE DIFFUSION • Concentration of a substance • Lipid solubility • Surface area of membrane • Thickness of membrane • Molecular weight of substance

  8. DIFFUSION (cont)

  9. MOVEMENT ALONG THE ELECTRICAL GRADIENT • Ions are electrically charged particles. • Movement of ions is also affected by their electric charge. • Cations (positively charged ions) move towards negatively charged area. • Anions (negatively charged ions) move toward positively charged area.

  10. Electrical Gradient (cont) • Therefore difference in CHARGE between two adjacent areas produces ELECTRICAL GRADIENT. • ELECTRICAL GRADIENT passively induces movement of ions. • There is ELECTRICAL GRADIENT between Intracellular fluid and Extracellular fluid.

  11. Electrochemical Gradient • When there is Electrical gradient (charge) and Concentration gradient (chemical) for ion it is referred ELECTROCHEMICAL GRADIENT. • REMEMBER THREE WORDS 1. Chemical gradient – concentration of ion 2. Electrical gradient – charge of ion 3. Electrochemical gradient – Both Electrical charge and concentration gradient

  12. OSMOSIS • If two solutions are separated by semi- permeable membrane or selectively permeable membrane, which allows water to cross but does not allow the solute (Na+) to pass, than water will pass from high concentration of water to low concentration of water. • This movement of water from high concentration to low concentration through selectively permeable membrane is called Osmosis.

  13. TONICITY • Tonicity—means concentration of Extracellular fluid. • Isotonic solution– means same concentration. Extracellular fluid (ECF) is isotonic to Intracellular fluid (ICF). • Hypotonic solution – below normal concentration. • Hypertonic solution – above normal concentration.

  14. TONICITY • Solve the problem • If RED BLOOD CELL (RBC) is put in Hypotonic solution, what will happen? • If RED BLOOD CELL (RBC) is put in Hypertonic solution, what will happen?

  15. SPECIAL MECHANISM FOR TRASPORT OF SUBSTACE ACROSS PLASMA MEMBRANE • How poorly lipid soluble molecules e.g. protein, glucose are transported across cell membrane? • To transport glucose, amino acid in the cell and transport waste products and secretary products out of cell, cell uses TWO different mechanisms. 1. Carrier mediated transport 2. Vesicular transport a). Endocytosis b). Exocytosis

  16. 1. Carrier mediated transport • i. Facilitated Diffusion • ii. Active Transport • TWO TYPES: A. Primary Active Transport B. Secondary Active Transport

  17. i. Facilitated Diffusion • Carrier is involved. • Carrier facilitates ( assists ) the substance to move from high concentration to low concentration. • No energy is required. • Example – glucose transport in cell.

  18. ii. Active Transport • It involves protein carrier to transfer the substance across the membrane. • It is from low concentration to high concentration. • Energy is required.

  19. ACTIVE TRANSPORT (cont) • TWO TYPES: A. Primary Active Transport B. Secondary Active Transport

  20. A. Primary Active Transport • In Primary Active Transport, energy is directly required to move a substance from low concentration to high concentration.

  21. B.Secondary Active Transport • In Secondary Active Transport, when Na+ and glucose are carried together, energy is required for Na+ to move it from lower concentration to higher concentration. • Now if glucose is also carried (co-transported with Na+) by the carrier – glucose gets free ride. • Therefore, glucose transport is called ‘Secondary Active Transport’.

  22. 2. Vesicular Transport • In Vesicular Transport , material is moved into or out of the cell, wrapped in membrane. • Vesicular Transport is of TWO types: i. Endocytosis ii. Exocytosis

  23. i.Endocytosis • Endocytosis means ‘substances are taken into the cell’. • Endocytosis of fluid is called ‘Pinocytosis’ (cell drinking). • Endocytosis of large particles e.g. bacteria is known as ‘Phagocytosis’ (cell eating). • Once inside the cell, Lysosomes unite the vesicle to kill the bacteria.

  24. ENDOCYTOSIS

  25. ii.Exocytosis • In Exocytosis, vesicle is formed within the cell. It fuses with plasma membrane then opens up and releases its content outside.

  26. Methods Of Membrane Transport • You should know 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Primary Active Transport 5. Secondary Active Transport 6. Endocytosis 7. Exocytosis

  27. Thank you

More Related