CELLULAR TRANSPORT

Chapter 8, Section 1

Osmosis

Diffusion = movement of molecules from an area of high concentration to an area of low concentration

Osmosis = diffusion of WATER across a membrane

Solutions

A solution typically consists of the dissolved material called the solute and the dissolving agent called the solvent. A common example is sugar (the solute) dissolved in water (the solvent).

When talking a about the cell and solutions, what we have is a cell membrane that allows only water to diffuse across it.

Direction of Osmosis (p.196)

Hypotonic = concentration of solutes outside of cell is lower than concentration of solutes in cytosol, water moves into cell

Hypertonic = conc. of solutes outside of cell is higher than conc. of solutes in cytosol, water moves out of cell

Isotonic = conc. of solutes inside & outside cell are equal, water moves in & out at equal rates

Practice

In 2007 a woman died participating in a California radio station contest to win a video game console. The coroner’s report indicated she died of water intoxication. During the contest, participants were given two minutes to drink a bottle of water and then given another bottle to drink after a 10 minute break. This was repeated for several times. Explain what was happening to the woman’s cells.

Passive Transport (p.198)

Cell does NOT use energy to move particles across the plasma membrane

Facilitated Diffusion = passive transport of materials using proteins

Active Transport (p. 199) Cell requires energy to move particles

from low concentration to high concentration

Transport of Large Particles (p. 200)

Endocytosis = cell surround and takes in materials from its environment

Exocytosis = cells release materials from the inside out into the environment

Practice

How would you expect the amount of mitochondria in a cell to be related to the amount of active transport it carries out? Explain your answer.