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Cellular Transport and the Cell Cycle (PowerPoint download)

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									Cellular Transport and the
Cell Cycle

        Unit 3
       Chapter 8
Different ways of transporting
materials across a cell membrane
1. Passive transport
  1.   Diffusion
  2.   Osmosis: water diffusion
  3.   Facilitated transport
2. Active transport
3. Exocytosis
4. Endocytosis
Cells in isotonic solutions
 Cell loses and gains
  water at an equal rate.

 Net change to cell =
  nothing
Isotonic solution
 Not ideal for plant cells
  because the cells
  become flaccid (limp)

 Ideal for animal cells or
  cells without cell walls
Cells in a hypotonic solution
 More water moves into
  the cell than moves out.

 Net change = cell mass
  increases
Hypotonic solution
 Ideal for plant cell
  where the cell becomes
  turgid (swollen)

 Not ideal for animal
  cells where the cell
  lyses (bursts)
Cells in a hypertonic solution
 More water moves out
  of the cell than moves
  in

 Net change = cell mass
  decreases
Hypertonic solution
 Not ideal for any cell
 Both shrink.
Passive transport
                     Movement of materials
                      across a cell membrane
                      in the direction of
                      higher concentration
                      to lower concentration
                     No ATP energy
                      required
Passive transport by proteins
                   Facilitated transport


                   Movement of chemicals
                    down a chemical
                    gradient (from high to
                    low concentration)
                    through a protein
Passive transport
Channel vs. carrier proteins



                               Click
                               on
                               image
                               to
                               view
                               video.
Active transport
 Requires energy to move substances across the
  membrane against the concentration gradient
  (from lower to higher concentration)




                                        Click on image
                                        to view video.
Exocytosis: transport of large particles
out of cell
Endocytosis: transport of large
particles inside of a cell
Cell reproduction: making new cells
by a process called cell division
                    Cell cycle: sequence of
                     growth and division of a
                     cell

                    Step 1: Interphase (G1,
                     S, G2)

                    Step 2: Mitosis and
                     Cytokinesis (M)
Eukaryotic chromosome structure
 Double helix coiled and
  twisted into a
  condensed structure

 Bacterial DNA differs in
  that it is circular and not
  linear.
Step 1: Interphase
 Grows in size
 Copies DNA




                  Each chromosome makes a copy, and the two
                  resulting chromosomes are joined at the
                  centromere.
Step 2: Mitosis (nuclear division)
 Prophase
 Metaphase
 Anaphase
 Telophase
Prophase: spindle fibers extend,
nuclear membrane disintegrates
Metaphase: chromosomes aligned
along the middle
Anaphase: chromosomes pulled apart
when spindle fibers become shorter
Telophase: two nucleus form at each
pole of the cell
Cytokinesis: forming two daughter
cells identical to the parent cell
 Animal cells:
  cell pinches
  down the
  middle

 Plant cells:
  cell plate
  forms to make
  new cell wall
Onion root tip showing phases of
mitosis
The cell cycle




          Click on image to view video.

								
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