Cell Transport
Getting Into and Out of Cells
Types of Cell Transport
 Passive Transport
- no cellular energy required to occur
- goes with the concentration gradient
- diffusion
- facilitated diffusion
- osmosis
 Active Transport
- requires cellular energy to occur
- goes against the concentration gradient
- Endocytosis/Exocytosis
Concentration Gradient
 The concentration gradient is the distribution of particles
across space from high to low concentration
Diffusion
 Primary means of cell transport
- molecules move from high to low concentration
- movement continues with the gradient until
the molecules are evenly distributed
- equilibrium is achieved
Passive Transport
 Energy for passive transport comes from the molecules
themselves
 In passive transport, molecules move with the
concentration gradient
- move from high concentration to low concentration
Facilitated Diffusion
 Particles move with the concentration gradient
across a transport protein in the membrane
- ions, sugar and amino acids all move into and
out of cells by facilitated diffusion
Osmosis
 Is the diffusion of water through a membrane .
 If the concentration of water is higher outside a cell than inside,
water moves into the cell.
 If the concentration of water is higher inside of a cell than
outside, the water moves out of the cell.
Active Transport
 Uses cellular energy/ ATP
 Goes against the concentration gradient
- Low concentration to High concentration
Endocytosis
o Endocytosis – taking things into cells
◦ Phagocytosis- cell eating – takes in food
◦ Pinocytosis- cell drinking – takes in liquid
- membrane encircles food or liquid, forming a vacuole
White blood cell engulfing
bacteria (bacillus)
Exocytosis
 Exocytosis-moving materials
out of cells
- wastes/ undigestible material
- cellular products like:
antibodies, hormones,
enzymes and
neurotransmitters
-vacuole/vesicle containing
the substance travels to
the cell membrane where
it fuses and releases it
contents out of the cell
Research 16.3
1)
2)
3)
4)
5)
6)
Describe diffusion using real world examples, and why it is
important to life functions
Describe how passive transport works and how does the
cell benefit from this?
Why do plant leaves shrink, and how can this be remedied?
Describe active transport, and why it is important.
What are the differences between endocytosis and
exocytosis, and why they are necessary?
How does cell size and shape affect cell transport?
Answers
1) When you walk into a bakery you can smell the bread baking. This
is the process of diffusion where molecules spread out and fill the
space. This helps cells maintain conditions necessary for life ex
oxygen enters cells and carbon dioxide leaves cells.
2)The materials move without using the cell’s energy. Cells benefit
from passive transport because some materials can move in or out
without any input of energy
3) Plants wilt due to osmosis where water moves through a
membrane. As the soil dries the water leave the plant cells by
osmosis and they shrink. This can be remedied by watering the plant
and water will fill the cells giving them shape
Answers
4) Active transport is the process of using energy to move
materials through a membrane. This is important to cells for
being able to remove excess salt from the body.
5) Endocytosis is where the cell moves materials that are too
large into the cell. Where as Exocytosis is the process of
moving materials that are too large out of the cell. This helps
your body defend against bacteria and viruses, and expel
proteins or hormones made by the cells.
Answers
6) The amount of cell membrane limits the ability of cells to
either get materials through the cell membrane this is related to
surface area. The larger a cell time comes when its surface area
is not large enough to allow resources to travel to all parts so it
stops growing. The cells shape affects the amount of surface
area.