CELL TRANSPORT

Tomato plant must take in nutrients from the soil. Potassium Nitrogen Phosphorus Every living cell exists in a liquid environment. One of the most important functions of the cell membrane is to keep the cell’s internal conditions relatively constant.

IN Food Glucose O2 H2O OUT Waste Hormone CO2 H2O What structure in the cell regulates what substances enter the cell? The cell membrane regulates and controls which substances enter and leave the cell.

There are two basic methods by which substances enter/exit the cell: (1) Passive transport --- no energy needed (2) Active transport --- requires energy

Passive transport is the movement of substances across a cell membrane from an area of higher concentration to an area of lower concentration. ( requires no energy ) aa sugarsaltO2O2 Higher Concentration Lower Concentration

InsideCell What are some characteristics of the cell membrane? Outside Cell Nonpolar---oily

InsideCell Small nonpolar substances such as CO 2, O 2, and small lipids can pass through the cell membrane by diffusion. lipids CO 2 O2O2 Outside Cell

Diffusion is the movement of substances from a region of higher concentration to a region of lower concentration. High Conc Low Conc Low Conc Low Conc higher conclower conc

Equilibrium is the condition in which the concentration of a substance is equal throughout a region. Even at equilibrium, molecules continue to move randomly.

Which way will fat move? inside cell outside cell fat LOW HIGH fat That’s diffusion!

InsideCell How do polar molecules like glucose get across the nonpolar membrane? Outside Cell Nonpolar--oily glucose By Facilitated Diffusion

Channel Proteins Facilitated Diffusion: The diffusion of substances across the cell membrane through channel proteins. passive transport No energy input substance higher conc lower conc

InsideCell Proteins in the cell membrane create channels making it easy for certain molecules to pass. Channel Proteins glucose

InsideCell Outside Cell Polar molecules like glucose diffuse across the membrane by moving through pores formed by channel proteins. Channel Proteins glucose

Osmosis Water is very important, so we talk about water separately. Cell survival depends on balancing water uptake & loss. freshwater balancedsaltwater Normal plant cell ******

Osmosis is the movement of water across a cell membrane from a region of higher conc to a region of lower conc. Osmosis is the diffusion of water across a cell membrane. high conc H 2 O low conc H 2 O Cellmembrane

high conc H 2 O low conc H 2 O Cellmembrane How does water move? Always from an area of higher concentration to an area of lower concentration.

The direction of osmosis depends on the relative concentration of solutes on the two sides of the membrane. low conc solutehigh conc solute Less water more water solute

How does water move? low conc solutehigh conc solute Less water more water solute more water less water

Cells are always surrounded by some kind of solution. The solution surrounding cells may be: (1) isotonic (2) hypotonic (3) hypertonic

An isotonic solution has the same concentration of solute molecules as the cell. iso = same 10 % solute 10 % solute Water moves in and out at the same rate

iso = same 2 % salt 2 % salt isotonic solution

iso = same 5 % glucose 5 % glucose isotonic solution

A hypotonic solution has a lower concentration of solutes than a cell. This means the concentration of water is greater outside the cell than inside. Water will move into the cell Hypo = more water 10 % solute 25 % solute The cell will swell. Less solute

1 % salt 5 % salt hypotonic solution

1 % glucose 2 % glucose hypotonic solution

A hypertonic solution has a higher conc of solutes than a cell. The water conc is lower outside the cell than inside. Water will move out of the cell The cell will shrivel. 25 % solute 5 % solute Hyper = less watermore solute

5 % salt 2 % salt hypertonic solution

3 % glucose 1 % glucose hypertonic solution

Summing Up! Passive Transport: Movement from high to low No energy Examples: diffusion facilitated diffusion osmosis

Contractile vacuole in Paramecium