Tonicity and Active Transport

1. Tonicity and Active Transport

2. Tonicity Tonicity: the concentration of solutes (dissolved substances) in a solution on either side of the membrane

3. Tonicity Remember these are comparative strengths based upon the amount of solute. • ISO means the same • HYPO means below/lower than normal/ under • HYPER means over/greater than normal/ excessive

4. TONICITY OF A SOLUTION The tonicity of a solution will affect the size & shape of cells: • ISOTONIC SOLUTION: • the solution concentration isequalon both sides of the membrane . • There is no net concentration difference across the cell membrane • Water moves back and forth, but there is no net gain or loss of water.

5. the cell stays the same

6. TONICITY OF A SOLUTION • HYPERTONIC SOLUTION: • The solution outside the cell is more concentrated than inside. • There is more water inside the cell and the water will move out of the cell. • This causes the cell to shrink

7. the cell shrinks

8. TONICITY OF A SOLUTION • HYPOTONIC SOLUTION: • The concentration inside the cell is more concentrated than outside. • Therefore there is more water outside of the cell, and water will move into the cell. • This will cause the cell to swell.

9. the cell expands or bursts

11. Hypertonic Isotonic Hypotonic In Biology we usually talk about the SOLUTION’S tonicity, NOT the cells!

13. hyper, hypo, or isotonic solution? hypertonic causes CRENATION

14. hyper, hypo, or isotonic solution? hypotonic causes HEMOLYSIS

15. hyper, hypo, or isotonic solution? isotonic

16. When we speak of plants, we speak of TURGOR PRESSURE. Which of these cells is in a hypertonic solution? Hypotonic?

17. Tonicity

18. ACTIVE TRANSPORT

19. Active transport moves molecules from [low] to [high],AGAINST the concentration gradient and this process requiresenergy in the form of ATP.

20. ACTIVE TRANSPORT Active Transport: the movement of polar, large, and charged molecules moving against the concentration gradient (uphill). EXAMPLES of molecules that move this way are: ions (like Na+ and K+ in cells, and iodine) and sugars, amino acids, nucleotides...

22. requires

23. LOW [ ] TO HIGH [ ]

24. GOITER

25. EXAMPLES OF ACTIVE TRANSPORT Example 2: a Na/K pump (mostly in nerve membranes). These function to restore electrical order in a nerve after an impulse has traveled along it. the Na/K Pump

26. where is active transport important?

27. Weeee!!! high low This is gonna be hard work!! high low Types of Cellular Transport • Passive Transport cell doesn’t use energy • Diffusion • Facilitated Diffusion • Osmosis • Active Transport cell does use energy • Protein Pumps • Endocytosis • Exocytosis

28. ENDOCYTOSIS & EXOCYTOSIS Aka BULK TRANSPORT

29. Endocytosis • Some things the cells needs are too large to pass through the cell membrane. • The cell membrane can surround a large particle located outside the cell. • The membrane forms a sac around the particle. • Then the sac opens inside the cell.

30. ENDOCYTOSIS Endocytosis: (“Endo” means “in”). Endocytosis is the taking in of molecules or particles by invagination of the cell membrane forming a vesicle. This requires energy.

32. requires

33. ENDOCYTOSIS There are two types of endocytosis: 1. pinocytosis (cell drinking): small molecules are ingested and a vesicle is immediately formed. This is seen in small intestine cells (villi) 2. phagocytosis (cell eating): large particles, (visible with light microscope) are invaginated into the cell (ie: white blood cells ‘eat’ bacteria).

36. phagocytosis

37. EXOCYTOSIS • Exocytosis: (“Exo” means “out”.) • Exocytosis is the reverse of endocytosis. • This is where a cell releases the contents of a vesicle outside of the cell. • These contents may be wastes, proteins, hormones, or some other product for secretion. • This also requires energy. • Example: vesicles from the Golgi fuse with the plasma membrane and the proteins are released outside of the cell.