Passive Transport

PASSIVE TRANSPORT

CHAPTER 5 SECTION 1

PASSIVE TRANSPORT

• MOVEMENT OF SUBSTANCES ACROSS A

CELL MEMBRANE WITHOUT AN INPUT OF
____ENERGY______ BY THE CELL.

• FOUR TYPES : __DIFFUSION______,

___OSMOSIS______, ___FACILITATED_____
___DIFFUSION_______, AND
_____DIFFUSION THROUGH ION
CHANNELS____.

Source:
https://sites.google.com/site/cserfass3rd
2014/home/3rd-period-biology-honors-
project/passivetransport

DIFFUSION

• DIFFUSION - MOVEMENT OF MOLECULES

FROM HIGH TO LOW CONCENTRATION

• THE DIFFERENCE IN CONCENTRATION OF

MOLECULES ACROSS A SPACE IS THE
___CONCENTRATION____
_____GRADIENT________.

• DIFFUSION IS DRIVEN BY THE

___KINETIC_____ ____ENERGY___ OF THE
MOLECULES.

Source:
https://biologydictionary
.net/passive-transport/

DIFFUSION

• EQUILIBRIUM – STATE IN WHICH THE

CONCENTRATION OF MOLECULES IS THE SAME
THROUGHOUT

• EVEN AT EQUILIBRIUM, RANDOM

____MOVEMENT______ OF MOLECULES
CONTINUES.

DIFFUSION

• MOLECULES THAT ARE

__NONPOLAR_____ (DISSOLVE
IN LIPIDS) AND THOSE THAT ARE
___SMALL____ ARE ABLE TO
DIFFUSE THROUGH THE CELL
MEMBRANE.

OSMOSIS

• OSMOSIS – A SPECIAL CASE OF

DIFFUSION IN WHICH ____WATER______
MOLECULES GO FROM A ___HIGH___
CONCENTRATION TO A
____LOW_______ CONCENTRATION.

• IF WATER CONCENTRATION IS HIGH,

SOLUTE CONCENTRATION IS LOW

Source: http://slideplayer.com/slide/7464257/

OSMOSIS

• IF WATER CONCENTRATION IS HIGH,

SOLUTE CONCENTRATION IS LOW

• IF WATER CONCENTRATION IS LOW,

SOLUTE CONCENTRATION IS HIGH

• WATER GOES FROM WHERE WATER IS

HIGH AND SOLUTES ARE LOW TO
WHERE WATER IS LOW AND SOLUTES
ARE HIGH

Source: http://slideplayer.com/slide/7464257/

OSMOSIS

• DIRECTION OF OSMOSIS

DETERMINED BY TYPE OF SOLUTION
THE CELL IS IN:

• HYPOTONIC – LESS SOLUTES

• HYPERTONIC – MORE SOLUTES

• ISOTONIC – SAME SOLUTES

Source: http://encyclopedia.lubopitko-bg.com/OsmosisAffectsCells.html

OSMOSIS

• ANIMAL CELLS LIKE TO BE IN AN

ISOTONIC SOLUTION.

• HYPOTONIC SOLUTIONS = COULD

BURST

• HYPERTONIC SOLUTIONS =

CRENATION

Source: http://encyclopedia.lubopitko-bg.com/OsmosisAffectsCells.html

OSMOSIS

• TWO WAYS UNICELLULAR ANIMALS OR

PROTISTS GET RID OF EXTRA WATER THAT
COMES IN DUE TO OSMOSIS IN HYPOTONIC
ENVIRONMENT:

• 1. CONTRACTILE VACUOLE

• 2. PUMP SOLUTES OUT OF CYTOSOL

• WHAT HAPPENS IF THEY CAN’T GET RID OF

THE EXTRA WATER? CYTOLYSIS (CELL
BURSTS)

Source: http://wiki.district87.org/index.php/Osmosis

OSMOSIS

• HYPOTONIC ENVIRONMENT IS NORMAL AND HEALTHY FOR PLANTS BECAUSE IT

CREATES TURGOR PRESSURE. WHAT IS TURGOR PRESSURE? THE PRESSURE WATER
MOLECULES EXERT ON THE CELL WALL

• WHAT IS PLASMOLYSIS? WHICH TYPE OF ENVIRONMENT WOULD CREATE THIS

CONDITION IN A PLANT CELL? WHEN THE CELL MEMBRANE SHRINKS AWAY FROM THE
CELL WALL; HAPPENS IN HYPERTONIC AND DRY ENVIRONMENTS

Source: https://en.wikipedia.org/wiki/Osmosis

FACILITATED DIFFUSION

• USED BY ___POLAR______ AND

____LARGE_______ MOLECULES

• FACILITATED DIFFUSION – DIFFUSION

WITH THE HELP OF ___CARRIER_____
____PROTEINS____.

• DOES IT REQUIRE ENERGY? NO; STILL

GOING FROM HIGH TO LOW
CONCENTRATION

Source:
http://ib.bioninja.com.au/standard-level/topic-1-cell-
biology/14-membrane-transport/facilitated-diffusion.html

FACILITATED DIFFUSION

• DOES IT TRANSPORT INTO A CELL,

OUT OF A CELL, OR BOTH? BOTH

• ___CARRIER____

____PROTEINS_____ THAT HELP
WITH DIFFUSION ARE SPECIFIC
FOR EACH MOLECULE THAT IS
TRANSPORTED.

Source:
http://ib.bioninja.com.au/standard-level/topic-1-cell-
biology/14-membrane-transport/facilitated-diffusion.html

DIFFUSION THROUGH ION CHANNELS

• __ION___ _____CHANNELS____ ARE SMALL PASSAGEWAYS THAT IONS CAN

PASS THROUGH.

• ION – CHARGED PARTICLE (ATOM OR MOLECULE)

• SOME ION CHANNELS HAVE GATES THAT CAN OPEN AND CLOSE

Source:
https://www.fastbleep.com
/biology-notes/40/1176