CELLS

1. CELLS Chapter 3

2. Molecules move across membranes in several ways

3. Passive transport • Two kinds • Diffusion • Osmosis

4. Diffusion and Concentration Gradients • Diffusion

5. Simple & Facilitated Diffusion • simple diffusion • facilitated diffusion

7. Defects in Transport Proteins • Can reduce or even bring facilitated diffusion to a complete stop • Serious health consequences • Many genetic diseases s/a cystinuria • when structured and functioning properly, this transport protein facilitates the diffusion of some amino acids (including cystine, from which the disease gets its name) out of the kidneys • when proteins are malformed, they cannot facilitate diffusion • amino acids build up in the kidneys, forming painful and dangerous kidney stones

8. Osmosis is the passive diffusion of water across a membrane

9. Direction of Osmosis • Determined by

10. An amoeba is placed in a solution. The volume of the cell increases (cell swells). The amoeba is in a hypertonic solution. Water is moving into the amoeba. The amoeba is in a isotonic solution. Water is moving out of the amoeba.

11. In active transport, cells use energy to move small molecules

12. Two types of active transport • Primary – • Secondary –

13. Primary Active Transport • To help break down food

14. Primary Active Transport

15. A normal cell has a high concentration of potassium on the inside and a low concentration of potassium on the outside. Also, a normal cell has a low concentration of sodium on the inside and a high concentration on the outside. Yet, the net movement of potassium is into the cell and the net movement of sodium is out of the cell. What type of transport is involved? Osmosis Facilitated transport Active transport Simple diffusion Secondary active transport

16. Secondary Active Transport • Transport protein simultaneously moves one molecule against its concentration gradient while letting another flow down its concentration gradient.

17. An intestinal epithelial cell powers the movement of glucose into the cell against its concentration gradient by simultaneously transporting sodium down its concentration gradient. Which transport mechanism is responsible? Osmosis Facilitated transport Active transport Simple diffusion Secondary active transport

18. Endocytosis and exocytosis are used for bulk transport of particles • Endocytosis: • Exocytosis:

19. Endocytosis and exocytosis are used for bulk transport of particles

20. 3 types of endocytosis • Phagocytosis – “cell eating” • Pinocytosis – “cell drinking” • Receptor-mediated endocytosis

23. Faulty cell membranes are a primary cause of cardiovascular disease • Cholesterol • large numbers of LDL receptors on liver cell  

24. Faulty cell membranes are a primary cause of cardiovascular disease • Those who consume food laden with too much cholesterol • This outcome can result in the early onset of cardiovascular disease. • Familial hypercholesterolemia –

25. Faulty cell membranes are a primary cause of cardiovascular disease

26. Cells are connected and communicate with each other

27. Connections between cells hold them in place and enable them to communicate with each other • Involves numerous types of protein and glycoprotein adhesion molecules

28. Tight Junctions • water-tight seals • anchor cells in place • small intestine

29. Desmosomes • fasten cells together • Velcro: • cavities of animal bodies

30. Gap Junctions • Pores • Large enough for • Too small for • cell-to-cell communication • heart: • cell recognition • chemicals flowing from one cell to the next

32. Your skin is water proof. What type of cell-cell junction is most likely involved in creating a water-tight barrier between the outside and inside of your body? Tight junctions Desmosomes Gap junctions

33. How can a lack of communication between cells lead to cancer? • Contact inhibition • Cancer cells

34. Plasmodesmata • Plant Cells