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Honors Biology Chapter 7Section 3 Cell Boundaries.

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1 Honors Biology Chapter 7Section 3 Cell Boundaries

2  surround all cells  is a thin, flexible barrier that acts like the cell’s “gate keeper”  made of lipid-bilayer  provides protection & support

3  Fluid Mosaic Model  phospholipids

4  resembles an ever-moving sea of fluid lipids that has large proteins bobbing along throughout the lipids

5 1. Phospholipids (~70% of membrane) 2. Cholesterol:  changes fluidity of membrane 3. Glycolipids  sugar molecule on lipid

6  Integral Proteins  go all the way thru the membrane  channel proteins  receptor proteins  Peripheral Proteins  on inside or outside of membrane  +/- attached to integral proteins


8  found in:  plant cells  fungi cells  algae  bacteria  secreted by cell membrane  allow O 2, CO 2, glucose, & H 2 O to pass through



11  all cells bathed in liquid  solutes dissolve in solvent (water)  concentration:  mass of the solute /vol of solution

12  does not require cell to spend energy to move substances  substances moving from area where it is in higher concentration  area where it is in lower concentration

13 1. simple diffusion 2. osmosis 3. facilitated diffusion

14  all particles have KE  due to the KE of particles they will move about until they are evenly distributed in the space they occupy  what we see is particles moving from where they are in high concentration  where they are in lower concentration

15  a form of passive transport  cell not spending nrg to make it happen  movement of particles continues even after equilibrium reached

16  when concentration of solutes equal thru out a system  since solute particles still moving it is also referred to as dynamic equilibrium

17  http://highered.mcgraw- pter2/animation__how_diffusion_works.html http://highered.mcgraw- pter2/animation__how_diffusion_works.html

18  is the diffusion of water across a semi-permeable membrane  it‘s water moving from where water is in high concentration  water is in lower concentration  semi-permeable = selectively permeable

19  Predict what will happen in the container on other side

20  water will move down its concentration gradient until equilibrium is reached  when concentrations of solutes same on both sides of membranes : equilibrium reached


22  cells are in isotonic solutions when the concentration of solutes inside cell = concentration of solutes outside cell  for human cells isotonic soultions = 0.9% NaCl


24  “above strength”  cells in ECF (extracellular fluid) with a higher concentration of solutes than inside cell  water in higher concentration inside cell so water leaves cell by osmosis…..cell shrinks….called crenation


26  called plasmolysis

27  “below strength”  water now in higher concentration in ECF so water will move from outside cell  inside cell…. cell swells and eventually pops….. called hemolysis if it is a RBC, other cells it is called: cytolysis




31  some substances move in/out of cells by diffusion but require a transport protein to cross the cell membrane  substance still moving from side with higher concentration  side with lower concentration  example: sugars move into cells by facilitated diffusion


33  y/Biology1111/animations/passive3.swf y/Biology1111/animations/passive3.swf

34  moving substances in/out of cell that requires cells to spend energy (usually in form of ATP)  substances are moving against their concentration gradients (from where they are in low concentration  high concentration)

35 1. Pumps 2. Endocytosis 3. Exocytosis

36  protein in cell membrane that “pumps” ion or molecule in/out of cell against its concentration gradient  most pumps use ATP as source of energy  most important pump is Na+/K+/ATPase pump


38  mplates/student_resources/shared_resources /animations/ion_pump/ionpump.html mplates/student_resources/shared_resources /animations/ion_pump/ionpump.html

39  process of cell taking up material into cell by means of infolding pockets of cell membrane

40  cell “eating”  done by unicellular organisms and phagocytes in multicellular organisms  macrophages


42  cell “drinking”  cells take up liquid from surroundings


44  when cells need to expel larger amounts of materials than can be expelled thru transport protein  storage vacuole moves to cell membrane; its membrane fuses with cell membrane expelling contents into ECF



47  endocytosis is removing some membrane from cell membrane  exocytosis is adding some membrane to cell membrane  usually evens out

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