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The Cell. Movement Across the Membrane. Cell Diagram: College of Dupage. Quiz. 1. What is the type of bond within a single water molecule? 2. A carboxyl group is symbolized by what? 3. Briefly explain what happens in a hydrolysis reaction.

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the cell

The Cell

Movement Across

the Membrane

Cell Diagram: College of Dupage

slide2
Quiz
  • 1. What is the type of bond within a single water molecule?
  • 2. A carboxyl group is symbolized by what?
  • 3. Briefly explain what happens in a hydrolysis reaction.
  • 4. Is maltose a monosaccharide, disaccharide, lipid, or protein?
quiz cont
Quiz cont.
  • 5. Are lipids hydrophobic or hydrophilic?
  • 6. What is the difference between a saturated vs unsaturated fatty acid?
  • 7. What does the secondary structure of protein refer to?
  • 8. How does an enzyme work?
quiz cont1
Quiz cont.
  • 9. What is the difference between filtration and diffusion?
  • 10. What happens to a rbc in a hypertonic solution?
  • A hypotonic solution?
c fluid mosaic model
C. Fluid Mosaic Model

Plasma membrane is oily film made of lipids with diverse proteins embedded in

Phospholipid bilayer

  • Hydrophillic heads facing water on either side of cell membrane
  • Hydrophobic tails directed to center

Proteins

-integral or transmembrane

-peripheral

functions of the cell membrane
Functions of the Cell Membrane
  • Defines boundaries of the cell
  • Governs interactions with other cells
  • Controls passage of materials into and out of cell
iii movement across membrane
III. Movement Across Membrane

A. Selective Permeability

Depends on

  • Size of particle
  • Solubility in lipids
  • Charge on particle

4. Carrier molecules in membrane

movement across membrane occurs through
Movement across membrane occurs through:
  • Lipid bilayer
  • Membrane channels
  • With carrier molecules
  • In vesicles
passive vs active transport
Passive vs. Active Transport

Requires ___________

  • Primary Active Transport
  • Secondary Active Transport
b non mediated transport mechanisms
B. Non-mediated Transport Mechanisms
  • Diffusion
  • Osmosis
  • Filtration
  • Passive
  • Requires no energy
b non mediated transport mechanisms1
B. Non-Mediated Transport Mechanisms

DIFFUSION = when molecules

move from a higher to a lower concentration.

What type of things might affect the rate of diffusion?

a. Magnitude of concentration gradient

b. Temperature

c. Size of diffusing particles

d. Viscosity (thickness) of solvent

Diffusion Animation: biologycorner.com

osmosis diffusion of water across the membrane
Osmosis: Diffusion of water across the membrane

Water moves from an area of more

water to an area of less water

osmotic pressure
Osmotic Pressure

Whenever dissolved substances such as glucose or protein are confined in a space by a selectively permeable membrane, they can pull water into the compartment by osmosis.

The strength of the osmotic pull is directly related to the concentration of the solution.

The greater the concentration, the greater the pulling, or osmotic pressure.

tonicity the ability of a solution to affect fluid volume and pressure within a cell
Tonicity =the ability of a solution to affect fluid volume and pressure within a cell

Environment surrounding cells may contain amounts of dissolved substances (solutes) that are…

equal to

less than

greater than

…those found within the cell.

Tonicity

Isotonic: no net movement of water between cell and environment

Hypertonic: a higher concentration of solute.

Hypotonic : a lower concentration of solute.

Water will always move toward a hypertonic environment!!

Diagrams:

Cell: College of DuPage

Osmosis - www.scienceaid.co.uk/biology/plants/osmosis.html

Blood Cells: Mariana Ruiz

effects of tonicity on rbcs water moves from an area of more water to an area of less water
Effects of tonicity on RBCs:Water moves from an area of more water to an area of less water

www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

effects of tonicity on rbcs
Effects of Tonicity on RBCs

Isotonic solutions: normal saline (0.9% NaCl), 5%D/W, and Ringer’s solution

Under special conditions, hypotonic or hypertonic solutions may be administered IV.

Most IV solutions are isotonic.

mediated transport mechanisms
Mediated Transport Mechanisms

Characteristics

1. Specificity- carrier exhibits specificity for certain ligand, just as an enzyme does for its substrate

2. Saturation- once all carriers occupied, adding solutes will not make the process go any faster

Three types

1. Facilitated Diffusion

2. Active Transport

3. Bulk Transport

facilitated diffusion
Facilitated Diffusion

Passive

-Proteins assist in diffusion of molecules across plasma membrane.

-Movement only occurs in the presence of a concentration gradient.

-Some molecules move across the membrane more quickly if diffusion is facilitated by a carrier molecule.

web references
Web References

www.susanahalpine.com/anim/Life/memb.htm

www.northland.cc.mn.us/biology/biology1111/animations/passive3.swf

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation_how_osmosis_works.html

www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

www.education.uoit.ca/lordec/ID_LORDEC/capillary_fluid/capillary_fluid_LO.swf

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation_how_facilitated_diffusion_works.html

review
Review

What are three examples of non-mediated transport mechanisms?

review1
Review

What are three examples of non-mediated transport mechanisms?

1. Diffusion

2. Osmosis

3. Filtration

review2
Review

What are three examples of non-mediated transport mechanisms?

1. Diffusion

2. Osmosis

3. Filtration

Are these active transport or passive transport?

review3
Review

1. Osmosis is best defined as the movement of

A) molecules from an area of high concentration to an area of lower concentration

B) molecules from an area of low concentration to an area of higher concentration

C) water molecules across a membrane from an area of low water concentration to an area of higher concentration

D) water molecules across a membrane from an area of high water concentration to an area of lower concentration

2. A red blood cell placed in a hypertonic solution will

A) Expand

B) Burst

C) Shrink

D) Have no change in shape

3. Facilitated diffusion requires

A) Enzymes C) lipid carriers

B) Carrier proteins D) carbohydrate carriers

review4
Review
  • The main difference between filtration and diffusion is
active transport
Active Transport

Transport of solute across membrane up (against) concentration gradient

Analogous to a pump moving water uphill.

ATP Driven Active Transport

Energy from adenosine triphosphate (ATP) drives substances across the plasma membrane with the aid of carrier molecules.

Examples: Sodium-potassium pump, bring amino acids into cell, pump Ca2+ out of cell

Diagram:

Cell, College of DuPage

sodium potassium pump
Sodium-Potassium Pump
  • Needed because Na+ and K+ constantly leak out of the cell
  • One ATP utilized to exchange three Na+ pushed out for two K+ brought in to cell
functions of na k pump
Functions of Na+ K+ Pump
  • Regulation of cell volume
  • Heat production (thyroid hormone increases number of pumps; heat a by-product
  • Maintenance of membrane potential in all cells
  • Secondary active transport (no ATP used)
vesicular transport
Vesicular Transport
  • Transport large particles or fluid droplets through membrane in vesicles (uses ATP)
  • Exocytosis
  • Endocytosis
    • Phagocytosis
    • Pinocytosis
    • Receptor mediated endocytosis
pinocytosis cell drinking
Pinocytosis= Cell Drinking

Taking in droplets of ECF

  • Occurs in all human cells

Membrane caves in, then pinches off into the cytoplasm as pinocytotic vesicle

transcytosis
Transcytosis
  • Transport of a substance across a cell
  • Capture on one side and release on the other side
  • Receptor mediated endocytosis moves it into cell and exocytosis moves it out the other side