Transcript down the concentration gradient

Homeostasis: Active & Passive
Transport
Type of solution
What is it
Which way will
water move
What happens to
a cell placed in the
solution?
Hypertonic
More solute
outside the cell
than inside the
cell
Outside the cell
Shrink
Hypotonic
More solute inside
the cell than
outside the cell
Inside the cell
Swell
Isotonic
Equal
concentration of
solutes inside and
outside the cell
Movement of
water is equal
nothing
Movement of water
• What will happen to a cell that is too
hypertonic?
– The cell will shrink
• What will happen to a cell that is too
hypotonic?
– The cell will burst!
Transport
• What does transport mean?
– The movement of something
• How many kinds are there?
–2
• What are they called?
– Passive transport and active transport
Passive Transport
• Definition: Movement of particles through the
plasma membrane with no energy
• Particles move down the concentration gradient
• What does this mean?
– Particles move from an area of high concentration to
low concentration
*(think of the tennis ball example)
Facilitated Diffusion
• Definition: passive transport of materials
across the membrane using transport proteins
• Channel proteins: form channels allowing
specific molecules to flow through
• Carrier proteins: change shape to allow a
substance to pass through the plasma
membrane
Specialized Passive Transport
• The movement of any molecule across a
selectively permeable membrane with the
concentration gradient is referred to as
Diffusion.
• The movement of H20 across a selectively
permeable membrane with the concentration
gradient is referred to as Osmosis.
Active Transport
• Definition: Movement of particles through a
membrane against a concentration gradient
• ***REQUIRES ENERGY!!!!!!!! ***:O
• Which way do particles move??
– LOW concentration to HIGH concentration
Active Transport
• Uses carrier proteins to move particles
against the concentration gradient
Passive vs. Active transport
Type of
transport
Transport
protein used
Direction of
movement
Requires
energy input
from cell?
Classification
of transport
Simple
diffusion
No
Down the
concentration
gradient
No
Passive
Facilitated
diffusion
Yes-channel
and/or carrier
proteins
Down the
concentration
gradient
No
Passive
Active
transport
Yes-carrier
proteins
Against the
concentration
gradient
yes
Active
Transport of large particles
• Endocytosis: Cell surrounds and takes in
material from the environment (Enters)
• Exocytosis: Cell expels (releases) material
from a cell (usually to remove wastes) (Exits)
What are buffers?
• Buffers are essential for many biochemical
processes. It serves to maintain the correct pH
and temperature necessary as many enzymes
work only under precise pH and temperature
conditions.
• Without buffers necessary chemical reactions
in cells would not happen resulting in cell
death.