Chapter 8 Cellular Transport & Cell Cycle

1. Chapter 8Cellular Transport & Cell Cycle

2. 8.1 Cellular Transport • Osmosis- diffusion of H2O • H2O moves freely through plasma membrane • H2O tries to maintain equal concentration on both sides of plasma membrane • Control of Osmosis • Concentration gradient- unequal distribution of particles

3. Isotonic solution • concentration of dissolved substances in solution = concentration inside cell • Cells in isotonic solution do not experience osmosis + retain normal shape ~ Fig. 8.2 p. 202 • Cells are not damaged

4. hypotonic solution • concentrate of solution < concentrate inside • H2O moves into cell • Cell swells • Internal pressure increases • Animal cells can burst • Plants cells cannot burst because of cell wall  becomes firm

5. hypertonic solution • concentrate of solution > concentrate inside • H2O moves out of cell by osmosis • Animal cells shrivel- inter pressure decreases • Plant cells- internal pressure decreases plant wilts

6. Passive Transport • Movement of particles such as lipids, lipid- soluble subs., & H2O across membranes using no E

7. Passive transport by proteins • Facilitated diffusion- passive transport of mat’ls across p.m. • W/ aid of transport proteins (fig. 8.5 p.204) transport proteins provide convenient opening for particles to pass through • Common method of moving sugars & a.a. across membranes • Factor- conc. grad.

8. Active Transport • Moving mat’ls against conc. grad.- from lower to higher concentrate • Requires E • How it happens- Fig. 8.6 p.205 • Carrier protein ( form of a transport protein) binds w/ particle of subs.- • Chemical E allows cell to shape of carrier protein so that particle to be moved is released on opposite side of membrane

9. Lg. Particle transport • Endocytosis- process by which a cell surrounds & takes in mat’l from environment • mat’l does not pass directly through membrane • engulfed by portion of p.m. • that portion of p.m. breaks away & resulting vacuole + contents moves into cell • active transport  + E

10. Lg. Particle transport • Exocytosis • opposite of endocytosis • used to expel wastes & secrete substances like hormones • active transport  + E

11. 8.2 Cell growth & Reproduction

12. Factors Limiting Cell Size • Diffusion is slow & inefficient over long distances & lg. Sizes • DNA • Limit to rate off genetic mat’l replication • In large cells, more than one nucleus has evolved • Surface Area (SA) to volume (V) Ratio • Volume increases faster then SA

13. Cell Reproduction • New cells made through cell division • Results in 2 identical cells

14. Chromosomes • Short, stingy, dark- staining structures in nucleus that contain DNA • Structure of eukaryotic chromosomes • Most of time, chromosomes exist as chromatin

15. Chromatin- long strands of DNA wrapped around proteins • As nucleus starts to divide, chromatin becomes, reorganized tightly packed chromosomes

16. Cell Cycle- Inside Story p.211 • Sequence of cell growth & division

17. Interphase- growth period in which a cell spends most of its life • Cell grows in size • Carries on metabolism • Chromosomes are duplicated • stages of interphase

18. Gl • beginning • chromosomes are not visible under light microscope because they are uncoiled • protein synthesis occurring rapidly

19. S stage • chromosomes replicated in nucleus

20. G2 • chromosomes begin to shorten & coil • high rate of protein synthesis • in animals, centriole pair replicates & prepares to form mitotic spindle • mitosis • follows interphase • nuclear division • process by which 2 daughter cells are formed, each containing a complete set of chromosomes

21. Cytokenisis • division of cytoplasm • after mitosis • chromosomes divide to form identical sister chromatids connected by a centromere

22. Phases of Mitosis

23. Prophase • 1st & longest phase • chromatin coils up into visible chromosomes • chromosomes look hairy • made up of 2 halves • sister chromatids held together by centromere • nucleus disappears • nuclear envelope & nucleolus disintegrate • in animal cells, centioles begin to migrate to opposite ends

24. Prophase

25. Centrioles • sm. Dark, cylindrical structures made of microtubules & are located just outside nucleus • as centrioles migrate, spindle, forms between them • Spindle • football shaped cage-like structure consisting of thin fibers of microtubules • in plant cells, spindle forms without centrioles

26. Metaphase • Short 2nd stage • Doubled chromosomes attach to spindle fibers by their centromeres • Chromosomes pulled by spindle fibers & line up at equator of spindle

27. Metaphase

28. Anaphase • 3rd Phase • beginning marked by separation of sister chromosomes • centromeres split apart • chromatid pair from each other • chromatids pulled apart by shortening of spindle fibers

29. Anaphase

30. Telephase • Fourth and final phase • Begins when chromatids reach the opposite poles • Many changes of prophase are reversed • Chromosomes unwind • Spindle begins to break down • Nucleolus reappears • Nuclear environment forms around each set of chromosomes • New double membrane begins to form between 2 new nuclei

31. Telephase

32. Cytokenisis • cytoplasm divides