Download Cell Transport PPT 2 File

Cell Transport
Miss P
2A/B Human Biological Science
Recap
• Cell Membrane = semi-permeable
• Passive = doesn’t require energy as
goes with the concentration gradient
(high to low)
• Active = requires energy as goes
against concentration gradient (low to
high)
Types of transport
Passive
• Diffusion
• Osmosis
• Facilitation
Diffusion
Active
• Active Transport
• Vesicular Transport
– Endocytosis
• Phagocytosis
• Pinocytosis
– Exocytosis
Diffusion
• Diffusion is the tendency for particles to
move from an area of higher
concentration to an area of lower
concentration.
• Diffusion results from the random
motion of atoms and molecules due to
their kinetic energy.
• Diffusion involves the movement of
atoms & molecules in gases and liquids
(specifically, solutes).
Diffusion
Simple diffusion
is the movement
of particles from
an area of high
concentration to
an area where
their
concentration is
lower.
Diagram created by LadyofHats
Concentration gradient
• When the concentration of a substance is
different at two places, the substance will
diffuse along the concentration gradient until
the concentration of the two areas becomes
equal.
High
concentration
Diffusion
gradient
Low
concentration
Concentration
at A
Concentration
at B
1
High
concentration
Diffusion
gradient
Low
concentration
2
3
Equilibrium
Uniform
concentration
Osmosis
• This is the diffusion of water across
a selectively permeable membrane.
• Water molecules move from high
concentration to low concentration.
• This is a passive process (does not
need ATP).
Osmosis
Low water
concentration
(concentrated
soln.)
Net water movement
from high conc. To
low conc.
Semipermeable
membrane
High water
concentration
(dilute soln.)
Facilitated diffusion
• Facilitated diffusion is a process of
diffusion where molecules diffuse
across cell membranes with the
assistance of transport proteins.
• Diffusion takes place from high
concentration to low concentration
and does not require ATP.
• Examples: glucose & amino acids.
Simple diffusion (left) &
facilitated diffusion
Diagram created by LadyofHats
Active transport
• Require energy (ATP).
• Substances move from low
concentration to high
concentration (i.e. against the
concentration gradient).
• Example: membrane pumps.
Active transport (sodium pump)
Diagram created by LadyofHats
Endocytosis
• Pinocytosis & phagocytosis are
specific types of endocytosis.
• Both processes involve cells
absorbing large particles such as
proteins (or even whole organisms,
such as bacteria & viruses) from
the outside by engulfing them with
their cell membrane to form a
vesicle (like a bubble) within the
cytosol.
Endocytosis & exocytosis
• Endocytosis = things entering the cell
–Phagocytosis = cell eating
–Pinocytosis = cell drinking
• Exocytosis = things leaving
(exiting) the cell
Endocytosis
Diagram created by LadyofHats
Exocytosis
Diagram created by LadyofHats