Anticipatory Set 9-15-11

Anticipatory Set 9-21-11 L2&3

Cellular Transport

Selective Permeability⌂ Selective permeability- the cell

membrane’s ability to allow some substances to enter/ exit but not all.

⌂ Two processes that allow substances to enter/exit:• Passive transport – energy from

kinetic energy and concentration gradient.

• Active transport-ATP

Diffusion⌂ Process depends on concentration gradient.

• Particles will never stop moving, but when equilibrium is reached there will be no net change in their concentration.

• Movement of particles is from [high] to [low] concentration.

• Dependent on four factors: diameter, temperature, electrical charge (when applicable), and the concentration gradient.

• Majority of materials enter cell through diffusion…energy conservation for other processes.

Cell Membrane & Diffusion⌂ diffusion animation

Osmosis⌂ Diffusion of water.

⌂ Water always travels from hypotonic to hypertonic

⌂ Solute always travels in opposite direction of water.

⌂ Osmosis Animation

Isotonic Solutions⌂ Isotonic solutions-

the same amount of solute exists inside and outside the cell.

⌂ Water moves in and out at the same rate.

Hypertonic Solutions⌂ Hypertonic

solutions- have more solutes in solution than inside the cell.

⌂ Water moves out of the cell to achieve equilibrium.

Hypotonic Solutions⌂ Hypotonic solutions-

have less solutes in them than inside the cell.

⌂ Water will enter the cell to try and achieve equilibrium.

⌂ Cells may lyse if too much water enters.

⌂ Plants combat this risk with their cell wall, and turgor pressure results.

Data Set 9

Level 1 and 1

Level 1 & 2

Level 1, 1, 2

Osmoregulation-water control

⌂ Turgid- enough water, plant cell rigid

⌂ Flaccid- lacking water, plant cell limp

⌂ Plasmolysis- cell membrane is ripped from cell wall

.

Animalcell

Lysed

H2O H2O H2O

Normal

Hypotonic solution Isotonic solution Hypertonic solution

H2O

Shriveled

H2OH2OH2OH2OPlantcell

Turgid (normal) Flaccid Plasmolyzed

Water Potential- water’s ability to do work when going through the C.M.

⌂ Pressure Potential• Positive pressure is

the cell being pushed

• Negative Pressure- the cell being pulled (eg transpiration)

⌂ Solute Potential- based on solute concentration

Positive Pressure Potential

Positive Pressure Potential

Negative Pressure Potential

Negative Pressure Potential

Solute Potential

ΨS = -iCRT

-i (ionization constant) C (molar concentration) R (pressure constant) T (temperature in Kelvin)

Turgor pressure is ~100psi, much more than a tire. The pressure is so great that plant cells would detach from one another if not for adhesive molecules known as pectins.

Facilitated Diffusion with Channel Proteins

⌂ Facilitated diffusion- within the cell membrane are channel proteins that allow materials to pass into the cell.

⌂ Aquaporins- channel proteins that allow water to pass through, in addition to simple diffusion.• In kidneys and plants

where water is essential• Channel Protein Animation

FD with Ion Channel Proteins⌂ Channel protein let in ions.⌂ When the protein shape changes, the gate

will open.⌂ Ions pass through based on size and

charge.⌂ Can be ligand gated or voltage gated.⌂ Voltage gated channels depend on two

things:• Concentration gradient of K

Concentration of K (usually higher inside cell)• Membrane potential due to charge imbalance.

Anticipatory Set 9-22-11Level 3

Facilitated Diffusion with Carrier Proteins

⌂ Carrier proteins transport polar substances like amino acids and sugars.

⌂ When the carrier proteins become saturated the rate of diffusion is maxed out.

⌂ Animation: How Facilitated Diffusion Works

Figure 5.12 A Carrier Protein Facilitates Diffusion (Part 1)

Filtration⌂ Filtration- pressure

driven system that pushes water and nutrients across cell membranes.

⌂ This is how urine is produced

⌂ Does not require energy.

Active Transport

Active Transport is Directional⌂ Active transport always works against

the concentration gradient. Going from a lower to higher concentration.

⌂ Requires energy.⌂ Two types: primary and secondary

active transport.

Membrane Proteins associated with Active Transport

⌂ Cell Pumps:⌂ Uniports move a single substance in one direction.⌂ Symports – move two substances in the same

direction.⌂ Antiports - move two substances in opposite

directions. One into the cell, and one out of the cell.• e.g. NaK pump

• Coupled transporters are those that move two substances. Which of these are coupled?

Figure 5.13 Three Types of Proteins for Active Transport

Primary Active Transport

⌂ ATP is hydrolyzed and drives the movement of ions against the concentration gradient.

⌂ Sodium potassium pump is an example of 1AT. Because the ions move against the concentration gradient. (Na leaves cell, although more Na outside cell, same with K more in cell, but K still enters)

⌂ NaK Pump located in all animal cells; antiport; coupled transporter

⌂ NaK Pump Simple Animation⌂ Na K Pump Animation

Figure 5.14 Primary Active Transport: The Sodium–Potassium Pump

Membrane Potential⌂ Membrane Potential aka Voltage

Gradient allows the cell to do work.

⌂ DNA is negative inside cell(-), NaK pumps extra Na out of the cell (+).

⌂ Difference in charge allows molecules to be transported using ATP.

⌂ E.g. glucose enters through because of membrane potential

⌂ Secondary AT Animation

H Pumps ⌂ Most important pump for

cell respiration and photosynthesis.

⌂ H+ pumped out of cell, and ions can now diffuse in

⌂ Pumping H requires little energy, and they help sugars enter the cell by AT

What if the macromolecules are too large, charged, or polar to enter through the membrane?

⌂ Is this a good problem or not?⌂ Which organelle is responsible for

substance transport?

Endocytosis⌂ Processes that bring

substances into the cell such as macromolecules and smaller cells.

⌂ Three types of endocytosis:• Phagocytosis• Pinocytosis• Receptor-Mediated Endocytosis

Figure 5.16 Endocytosis and Exocytosis (A)

Phagocytosis

• Cell eating• Part of cell membrane engulfs particles/cells• Phagosome fuses with a lysosome and digestion occurs

Endocytosis⌂ Phagocytosis- process fairly nonspecific⌂ Only a few cells can do this ex. WBC

• Must be able to change shape and form pseudopodia.

• WBC will attach to bacteria engulf bacteria with pseudopodia lysosomes with enzymes digest it residual waste is exocytosed.

• Pinocytosis- same process just with liquids. Also fairly nonspecific.

• WBC and Phagocytosis Animation

Receptor-Mediated Endocytosis⌂ Specific process that utilizes integral

membrane proteins to bind to specific molecules in the cell’s environment.

⌂ Receptor proteins are substance specific, aka coated pits. Coated with protein , formed by CM depressions.

⌂ When a ligand binds to the receptor protein, it invaginates and forms a vesicle.

⌂ E.g. cholesterol uptake in mammals rd. 113-114

Figure 5.17 Formation of a Coated Vesicle (Part 1)

Figure 5.17 Formation of a Coated Vesicle (Part 2)

Receptors will form a new vesicle and be recycled back to plasma membrane.

Exocytosis⌂ Anything that comes in must

go out. ⌂ Materials are packaged into

vesicles, which fuse with the cell membrane via a membrane protein.

⌂ The two membranes fuse, contents expelled, and the CM incorporates vesicle membrane.

Endocytosis and Exocytosis Animation

Hyper,Hypo,Iso

Other Cell Membrane Functions

⌂ Some organelle membranes help transform energy.

⌂ Some membrane proteins organize chemical reactions.

⌂ Some membrane proteins process information.

Plasmolysis⌂ Net loss of a cell’s volume

due to a hypertonic environment.

⌂ Plasmolysis Animation

Water Potential⌂ Tendency of water to leave one place in favor of

another.⌂ Always moves from higher to lower water potential.⌂ Affected by pressure and solute⌂ Water potential () = pressure potential (p) + solute

potential (s)⌂ Solute Potential = s=–iCRT

• i = The number of particles the molecule will make in water; for NaCl this would be 2; for sucrose or glucose, this number is 1

• C = Molar concentration (from your experimental data) • R = Pressure constant = 0.0831 liter bar/mole K • T = Temperature in degrees Kelvin = 273 + °C of solution

Water Pot. and Plasmolysis

Lab: Plasmolysis⌂ Perform a serial dilution of salt (100,

50, 25, 0% solution)⌂ Predict which solution will yield the

fastest plasmolysis results.⌂ Perform Experiment with each solution

and time results.

Lab: Water Potential⌂ Perform a serial dilution of sugar

( 100, 50, 25, 0). Label solutions.⌂ Core equal lengths of 2 vegetables.⌂ Record lengths, mass, and vegetable

type in table.⌂ Predict what will happen to length

and mass by tomorrow.

Anticipatory Set 10-10-11 Level 2