Cellular Transport And the Cell Cycle

1. Cellular Transport And the Cell Cycle

2. Diffusion • At all temperatures above absolute zero, the individual atoms that constitute any substance are always in movement. Indeed, the amount of this movement is what constitutes temperature itself. • Simply put, diffusion is the movement of particles from a region of high concentration to an area of lower concentration

3. Particles of a substance will move from a region of high concentration to a region of lower concentration. The difference in concentration of atoms is know as a concentration gradient As particles move in a given area, an equilibrium is reached where the space between the particles becomes fairly uniform. This equal distribution of atoms is called dynamic equilibrium Diffusion Cont.

4. Diffusion Cont. • Follow link to animation of diffusion The Diffusion Applet • Follow link to tutorial of diffusion and osmosis Diffusion and osmosis tutorial

5. Plasma Membrane • Made up of two layers of phospholipids • Controls what moves into and out of the cell • Selectively permeable

6. Passive Transport • Transport (diffusion) of particles across the membrane without the use of energy by the cell • Particles move from a region of high concentration to a region of low concentration across the concentration gradient

7. Passive transport by proteins Facilitated Diffusion - Transport of materials across the plasma membrane with the aid of channel proteins • Common method for moving sugars and amino acids across membranes • Driven by a concentration gradient (substances on both sides of the membrane are trying to reach equal concentration)

8. Passive Transport • Video

9. What is Osmosis? • Osmosis – Diffusion of water across a selectively permeable membrane • The plasma membrane does not limit the diffusion of water • In a cell, water always tries to reach an equal concentration on both sides of the membrane • Regulation of water flow through the membrane is important in maintaining homeostasis

10. What Controls Osmosis? • Concentration gradient - Unequal distribution of particles

11. Cells in an Isotonic Solution • Isotonic Solution – when the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside of the cell • Equal movement of water into and out of the cell, cell stays the same size

12. Cells in a hypotonic solution • Hypotonic solution – when the concentration of dissolved substances is lower in the solution outside the cell than the concentration inside the cell • Water is pulled into the cell, the cell swells and the internal pressure increases

13. Cells in a hypertonic solution • Hypertonic Solution – where the concentration of dissolved substances outside the cell is higher than the concentration inside the cell. • Water moves out of the cell, the cell shrinks, and internal pressure decreases

14. Water moves into a cell placed in a ___________________ solution. • Osmotic • Hypertonic • Isotonic • Hypotonic

15. Water moves out of a cell if it is placed in a _______________ solution • Hypotonic • Hypertonic • Isotonic • Passive

16. A cell moves particles from a region of lesser concentration to a region of greater concentration by _________________. • Facilitated Diffusion • Passive Transport • Osmosis • Active Transport

17. If a cell is placed in salt water, water leaves the cell by _____________. • Osmosis • Diffusion • Active transport • Phagocytosis

18. After viewing the recipe above, explain the role of osmosis in making pickles. Be ready to share your answers!

19. Active Transport • Cells can move particles from a region of low concentration to a region of high concentration, but it takes ! • Active Transport – movement of materials through a membrane against the concentration gradient energy

20. Active Transport Cont. • Proteins in the cell membrane (Carrier proteins) bind with particles of the substance. When the right molecule binds to the right carrier protein, chemical energy allows the carrier protein to change shape so that the particle can be moved to the other side of the membrane

22. Transport of Large Particles • Some cells can take in large molecules, groups of molecules, or even whole cells • Endocytosis – process by which a cell engulfs a material and forms a vacuole inside of the cell • Exocytosis – expulsion or secretion of materials from the cell • Used to get rid of waste, secrete hormones • Both endocytosis and exocytosis require cellular energy (Active transport)

23. Endocytosis

24. Exocytosis

25. Endocytosis and Exotytosis • Use the play dough to model the processes of endocytosis and exocytosis. Be able to explain the process. When you have finished, wait for Mrs. Johnson to come and check your work and hear your explanation.

26. Active Transport • Video

27. Release of waste or large cell products from inside to outside of cell _____________________. • Endocytosis • Exocytosis • Osmosis • Facilitated Diffusion

28. Type of cell transport which requires energy from the cell. • Osmosis • Facilitated Diffusion • Active Transport • Passive Transport

29. Active Transport is to carrier protein as _____________ is to channel protein. • Osmosis • Endocytosis • Exocytosis • Facilitated Diffusion

30. When cell engulfs a large particle • and forms a vacuole inside the cell • _____________________. • Endocytosis • Exocytosis • Osmosis • Facilitated Diffusion

31. Term for “cell eating” • Osmosis • Exocytosis • Pinocytosis • Phagocytosis

32. Cell Growth

33. Cells come in different sizes • Red blood Cells = 8 µm • Some nerve cells can be up to 1mm in length • The yolk of an Ostrich egg measures 8cm • Most living cells are between 2 and 200 µm • Given the wide range of cell sizes, why can’t most organisms be just one giant cell?

34. What limits cell size? • Diffusion • Diffusion is fast and efficient over short distances but slow and inefficient over larger distances • a mitochondrion at the center of a hypothetical cell with a diameter of 20 cm would have to wait months before receiving molecules entering the cell

35. What limits cell size? cont. • DNA • The nucleus contains blueprints for the cell’s proteins (proteins are used throughout the cell by the organelles) • There is a limit as to how quickly the DNA (blueprints) can be copied • The cell can’t survive unless there is enough DNA to support the protein needs of the cell • Some large single celled organisms have developed more than 1 nucleus

36. What limits cell size? Cont. • Surface area to volume ratio • As cell size increases, its volume increases faster than its surface area • If cell size doubles, the cell would require eight times more nutrients and would have eight times more waste to excrete. The surface area would increase only by a factor of four. The plasma membrane would not have enough surface area for nutrients, waste and oxygen to diffuse through

37. 1mm 1mm 2mm 2mm 4mm 4mm Surface area to volume ratio Surface area = 6mm2 Volume = 1mm3 Surface area = 24mm2 Volume = 8mm3 Surface area = ?? Volume = ?? Refer to PS lab 8.1 pg 209

38. Cell Size • Video

39. To summarize…. • Substances move into and out of cells • Passive transport • Diffusion • Osmosis • Facilitated diffusion • Active transport • Carrier proteins • Endocytosis/Exocytosis • Cell size must be limited in order for a cell to function effectively • Video

40. The structure most responsible for maintaining cell homeostasis is the ___________. • Cytoplasm • Mitochondria • Cell Wall • Plasma Membrane

41. Which of the following explain why a cell’s size is limited? • Volume increases faster than surface area • Surface area increases faster than volume • Homeostasis is disrupted by a cell that is too large • Both a and c

42. As a cell grows, its ___________ increases more than its ___________. • Length, volume • Width, surface area • Volume, surface area • None of these

43. Cell Reproduction

44. Cell Reproduction (video clip) • The cell theory states: all cells come from preexisting cells • We know that all organisms grow and change • Throughout our lives, worn-out tissues are repaired or replace by new cells • All of this occurs through Cell Division • The process by which new cells are produced from one cell • Results in two cells that are identical to the parent cell

45. What are Chromosomes? • Chromosomes – dark staining structures that contain genetic material (DNA) • Made up of DNA and protein • Chromatin – long strands of DNA wrapped around protein (resembles a tangled plate of spaghetti) • Before a cell can divide, the long strands of chromatin must be organized into a chromosome http://www.sirinet.net/~jgjohnso/modchromosome.jpg

46. Chromosomes http://www.uic.edu/classes/bios/bios100/labs/realchromo.jpeg

47. Video clip http://lhs.lps.org/staff/sputnam/Biology/U3Cell/chromosome_1.png

48. The Cell Cycle • The sequence of growth and division of a cell • 2 phases: • Growth • Division

49. The Growth Phase: Interphase • The majority of a cell’s life is spent growing and making more DNA, this period is called – Interphase • During interphase, cell grows in size and the chromosomes are duplicated • G1 phase - rapid growth • S phase – DNA synthesis and replication • G2 phase – Centrioles replicate and cell prepares for division

50. The Division Phase:Mitosis • Cells undergo mitosis as they approach the maximum cell size at which the nucleus can provide blue-prints for proteins and the plasma membrane can efficiently transport nutrients and waste into and out of the cell • 4 phases of Mitosis: Prophase Metaphase Anaphase Telophase