Biology AHSGE

Standard II- Cell Processes

Biology AHSGEBiology AHSGE

Standard 2. Describe cell processes necessary for achieving homeostasis, including active and passive transport, osmosis, diffusion, exocytosis, and endocytosis.

A. Recognize and apply the definition of homeostasis. B. Recognize and apply the definition of active transport. (The

movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.)

C. Recognize and apply the definition of passive transport.

Biology AHSGEBiology AHSGED. Recognize and apply the definition of osmosis. (The movement of

water across a selectively permeable membrane.)E. Recognize and apply the definition of diffusion. (The spontaneous

tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area.)

F. Recognize and apply the definition of exocytosis. (The cellular secretion of macromolecules by the fusion of vesicles with the cell membrane.)

G. Recognize and apply the definition of endocytosis. (The cellular uptake of macromolecules and particulate substances by localized regions of the cell membrane that surround the substance and pinch off to form an intracellular vesicle.)

HomeostasisHomeostasisThe ability of an organism or cell to maintain internal

balance and stability by adjusting its physiological processes.

If normal state is not restored, death might occur.Processes involved in homeostasis:

Nutrition- Use of nutrientsDigestion- Break down of materials into usable substances

Absorption- Ability of an organism/cell to take in materials from the outside environment

Transport- Movement of substances within an organism/cell

Biosynthesis- Making new compounds for growth, repair, or reproduction

HomeostasisHomeostasisHomeostasis processes cont’d:

Secretion- Release of substances within an organism/cell

Respiration- Release of energy from the breakdown of chemical compounds in the mitochondria

Photosynthesis- Autotrophic production of glucose from CO2 and H2O

Excretion- Rid of waste products to the outside of the organism/cell

Response- Reaction due to a stimulusReproduction (Fission)- Production of new cells by one cell dividing (mitosis and meiosis)

Passive TransportPassive TransportPassive Transport- The

diffusion of a substance across a biological membrane.

Diffusion- The net movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance.

High concentration to lower concentration

Requires no energyWill continue until all

concentrations are the sameDynamic equilibrium-

Particles will continue to move without an overall change in concentration.

DiffusionDiffusion

DiffusionDiffusion

3 factors affect rate of diffusion: Concentration (amount of a substance)Temperature (average kinetic energy of the particles)Pressure (Force of particles against the area of

membrane)In each case, the higher, the fasterMore collisions occur causing diffusion to occur

faster

Facilitated DiffusionFacilitated DiffusionFacilitated diffusion- Uses

transport proteins to move other ions and small molecules across the plasma membrane

Passive transport because it does not require energy

Water can diffuse across the membrane, but most other substances can not

Can use water-filled transport (channel) proteins or

Carrier proteins (change shape as material passes through)

OsmosisOsmosisOsmosis- Diffusion of water across a selectively

permeable membraneIn a solution, a solute is dissolved into a solvent.Water is the solvent in a cell and its environment

OsmosisOsmosis

Hypotonic Solution- Solution has a lower concentration of solute and higher concentration of solvent.

Cell will be cell will be hypertonicNet movement of water will be into

the cell, causing the cell to swellIn pure solvents, cells will burst

Ex: Distilled water, pure vinegar

Hypertonic solution- Solution has a higher concentration of solute and a lower concentration of solvent.

Cell will be hypotonicNet movement of water

will be out of the cell, causing the cell to shrink

OsmosisOsmosisIsotonic Solution- The solution has the same

concentrations of solutes and solvents as the cell.Cell is also isotonicWater will enter and leave the cell at equal rates, allowing for

the cell to remain unchanged.

Osmosis Practice Osmosis Practice

Active TransportActive Transport

Active transport- Movement of substances across the membrane from an area of lower concentration to an area of higher concentration; against the concentration gradient.

Requires energyUses carrier proteins called pumpsMaintains the proper balance of substances it needs

to maintain homeostasis

Active TransportActive TransportSodium-potassium ATPase Pump

Found in cell membrane of animal cells

Uses energy to transport 3 sodium ions out, while moving two potassium ions in (decreases sodium concentration inside the cell)

Coupled transport- Sugar molecules attach to sodium ions to be transported into the cell without energy through the coupled channel

Active TransportActive TransportEndocytosis- Cell surrounds a

substance in the outside environment, enclosing it in a portion of the membrane.

Pinches off into a vacuolePinocytosis- Cell drinkingPhagocytosis- Cell eating

Exocytosis- Vesicles surround waste inside the cell, attach to the cell membrane, and expel materials to the outside environment.