Cellular TransportCellular TransportIts how we maintain Its how we maintain

homeostasis homeostasis salt viewed under a microscopesalt viewed under a microscope

ObjectivesObjectives1. Explain how equilibrium is 1. Explain how equilibrium is

established as a result of diffusion established as a result of diffusion

2. Distinguish between osmosis and 2. Distinguish between osmosis and diffusion. diffusion.

3. Explain how substances cross the 3. Explain how substances cross the cell membrane through facilitated cell membrane through facilitated diffusion. diffusion.

4. Explain how Ion channels assist the 4. Explain how Ion channels assist the diffusion of ions across the memb. diffusion of ions across the memb.

1. Toward what condition 1. Toward what condition does diffusion eventually does diffusion eventually

lead in the absence of other lead in the absence of other influences? influences?

Eerie, dramatic pictures from the Hubble Eerie, dramatic pictures from the Hubble telescope show newborn stars emerging telescope show newborn stars emerging from "eggs“, compact pockets of from "eggs“, compact pockets of interstellar gas called evaporating interstellar gas called evaporating gaseous globules). Hubble found the gaseous globules). Hubble found the "EGGs," appropriately enough, in the "EGGs," appropriately enough, in the Eagle nebula, a nearby star-forming Eagle nebula, a nearby star-forming region 7,000 light-years from Earth in region 7,000 light-years from Earth in the constellation Serpens. the constellation Serpens.

These striking pictures resolve the EGGs at These striking pictures resolve the EGGs at the tip of finger-like features protruding the tip of finger-like features protruding from monstrous columns of cold gas and from monstrous columns of cold gas and dust in the Eagle Nebula (also called dust in the Eagle Nebula (also called M16). The columns — dubbed "elephant M16). The columns — dubbed "elephant trunks" — protrude from the wall of a trunks" — protrude from the wall of a vast cloud of molecular hydrogen, like vast cloud of molecular hydrogen, like stalagmites rising above the floor of a stalagmites rising above the floor of a cavern. Inside the gaseous towers, cavern. Inside the gaseous towers, which are light-years long, the which are light-years long, the interstellar gas is dense enough to interstellar gas is dense enough to collapse under its own weight, forming collapse under its own weight, forming young stars that continue to grow as young stars that continue to grow as they accumulate more and more mass they accumulate more and more mass from their surroundings.from their surroundings.

what condition does what condition does diffusion eventually diffusion eventually lead toward in the lead toward in the absence of other absence of other

influences?influences?-Equilibrium, which occurs when the -Equilibrium, which occurs when the concentration of molecules is the same concentration of molecules is the same throughout a space. Incidentally all of throughout a space. Incidentally all of

the universe will eventually reach the universe will eventually reach equilibriumequilibrium

2. How is osmosis related 2. How is osmosis related to diffusion? to diffusion?

-Diffusion: the -Diffusion: the movement of movement of molecules from molecules from areas of high to areas of high to low concentrationlow concentration

-Osmosis: the -Osmosis: the diffusion of water diffusion of water across a across a membranemembrane

3. If the concentration of 3. If the concentration of solute molecules outside a solute molecules outside a cell is lower than the cell is lower than the concentration in the cytosol, concentration in the cytosol, is the external solution is the external solution Hypotonic, hypertonic, or Hypotonic, hypertonic, or isotonic to the cytosol?isotonic to the cytosol?

Hypotonic Hypotonic

4. What role do carrier 4. What role do carrier proteins play in facilitated proteins play in facilitated

transport?transport? LONDON, England LONDON, England

(Reuters) --(Reuters) -- The The secret of carrier secret of carrier pigeons' uncanny pigeons' uncanny ability to find their ability to find their way home has been way home has been discovered by discovered by British scientists: British scientists: The feathered The feathered navigators follow navigators follow the roads just like the roads just like we do.we do.

4. What role do carrier 4. What role do carrier proteins play in facilitated proteins play in facilitated

transport?transport? - They bind to - They bind to

specific substances specific substances on one side of the on one side of the cell membrane, cell membrane, change shape and change shape and release the release the substances on the substances on the other side. They other side. They take things from take things from outside to inside outside to inside the cell. the cell.

5. How is facilitated 5. How is facilitated diffusion similar to diffusion similar to

diffusion through ion diffusion through ion channels?channels?

-Both help specific substances move -Both help specific substances move down their concentration gradient down their concentration gradient from one side of the cell membrane from one side of the cell membrane to the other, without an input of to the other, without an input of energy by cells. Both also involve energy by cells. Both also involve membrane proteins. membrane proteins.

6. Sea water has a higher concentration of solutes than 6. Sea water has a higher concentration of solutes than do human body cells. Why might drinking large do human body cells. Why might drinking large amounts of sea water be dangerous to humans?amounts of sea water be dangerous to humans?

- The solutes in the - The solutes in the sea water would sea water would make the solution make the solution outside the body outside the body cells more cells more concentrated. concentrated. Water would then Water would then diffuse out of the diffuse out of the cells, causing them cells, causing them to shrink and die. to shrink and die.

Osmoregulation for fishOsmoregulation for fish

How do How do fish deal fish deal with the with the different different tonicity tonicity between between salt and salt and fresh fresh water?water?

Freshwater fish face two problems: 1) getting rid Freshwater fish face two problems: 1) getting rid of excess water and 2) maintaining proper salt of excess water and 2) maintaining proper salt content in their bodies. Their bodies need to content in their bodies. Their bodies need to maintain a higher level of salt than the maintain a higher level of salt than the surrounding water. As H2O passes in through surrounding water. As H2O passes in through their gill, Na+ is lost. To counter act this their gill, Na+ is lost. To counter act this problem, freshwater fish drink constantly to problem, freshwater fish drink constantly to maintain proper ionic levels. These ions obtained maintain proper ionic levels. These ions obtained from drinking are transferred to the blood from drinking are transferred to the blood through the kidney via the "Bowman's capsule". through the kidney via the "Bowman's capsule". Ions obtained through osmosis at the gill have a Ions obtained through osmosis at the gill have a direct link to the blood via specialized "Chloride direct link to the blood via specialized "Chloride cells" in the gill. The efficient kidney enables the cells" in the gill. The efficient kidney enables the fish to excrete H2O very rapidly as a dilute urine. fish to excrete H2O very rapidly as a dilute urine. Na+ loss is greatly reduced by efficient Na+ loss is greatly reduced by efficient reabsorption from the urine before it is excreted.reabsorption from the urine before it is excreted.

The Nile Perch is the largest fresh water The Nile Perch is the largest fresh water fish available to anglers!!fish available to anglers!!

Marine fish experience just the opposite effect because their internal salt content is less than that of the surrounding water. They loose water by osmosis and gain salts by diffusion. The effect is also worsened by a more permeable membrane. Marine fish also drink large amounts of water but their kidney functions differently. They pass small amounts of very dilute urine. Between 7 to 35% of their body weight is drank each day. Most of the H2O is retained to counteract the H2O lost via osmosis at the gill. Marine fish produce a daily urine amount about 1/10 to 1/20 of freshwater fishes. Terrestrial vertebrates produce approximately 1.5% of their total body weight in urine daily. Freshwater fish produce 20% daily! As you can see, marine fish pass considerably less urine than freshwater fishes.

Active Transport Active Transport

Objectives: Objectives:

1. Distinguish between active and 1. Distinguish between active and passive transportpassive transport

2. Explain how the sodium-potassium 2. Explain how the sodium-potassium pump operatespump operates

3. Compare and contrast endocytosis 3. Compare and contrast endocytosis and exocytosisand exocytosis

1. Explain the difference 1. Explain the difference between active and passive between active and passive

transporttransport Passive transport: Moves molecules Passive transport: Moves molecules

down their concentration gradient, from down their concentration gradient, from areas of high concentration to low areas of high concentration to low concentration. It does concentration. It does notnot require require energy from the cell. energy from the cell.

Active transport: Moves molecules up Active transport: Moves molecules up their concentration gradient, from areas their concentration gradient, from areas of low concentration to high of low concentration to high concentration. It does require energy concentration. It does require energy from the cell.from the cell.

2. What function do carrier 2. What function do carrier proteins perform in active proteins perform in active

transport?transport?

- They bind to specific - They bind to specific molecules on one side of the molecules on one side of the cell membrane and transport cell membrane and transport the molecules up their the molecules up their concentration gradient to the concentration gradient to the other side of the membraneother side of the membrane

3. What provides the energy that drives the 3. What provides the energy that drives the

sodium potassium pump?sodium potassium pump? - The removal of a phosphate group from - The removal of a phosphate group from

ATP supplies the energy ATP supplies the energy

4. Explain the difference 4. Explain the difference between pinocytosis and between pinocytosis and

phagocytosisphagocytosis -Pinocytosis: -Pinocytosis:

transport of transport of solutes or fluids solutes or fluids into cellsinto cells

-Phagocytosis: the -Phagocytosis: the movement of large movement of large particles into cellsparticles into cells

Amoeba showing Amoeba showing pinocytosispinocytosis

5. Describe the steps 5. Describe the steps involved in exocytosis.involved in exocytosis.

- During exocytosis - During exocytosis cytoplasmic cytoplasmic vesicles fuse with vesicles fuse with the cell membrane the cell membrane and release their and release their contents outside contents outside the cellthe cell

6. During intense exercise potassium tends to 6. During intense exercise potassium tends to accumulate in the fluid surrounding muscle cells. What accumulate in the fluid surrounding muscle cells. What

membrane protein helps muscle cells counteract this membrane protein helps muscle cells counteract this tendency? Explaintendency? Explain

- The sodium-- The sodium-potassium potassium pump does pump does this by this by transportintransporting potassium g potassium into the into the cells in cells in exchange exchange for sodium. for sodium.

The End,The End,You stay classy biology You stay classy biology

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