Transcript Membrane Transport - Liberty Union High School District

Membrane Transport
• There are many molecules on (peripheral),
within (trans), and inside (intracellular) the
cell membranes. These all aid in getting
necessary molecules into and out of the cell.
They also play a role in cell to cell
communication.
• Most are proteins with or without
carbohydrates or lipids attached
These structures make membrane
Selectively permeable
• : The cell membrane acts like a wall around
the cell but it does have pores that act like
doors (see page 97)
• Some molecules are brought into the cell
and it TAKES energy to do this. ACTIVE
TRANSPORT
• Some molecules can flow through without
costing the cell any energy. PASSIVE
TRANSPORT
Passive Transport & examples
• Osmosis: The movement of water from High to low
concentrations.Aquaporins for diffusion of water,
• Filtration: process that is driven by hydrostatic
pressure (pressure from water) it drives particles in
and out of cell
• Blood pressure forces fluid through gaps in capillary
walls
• Water, salts, nutrients are transferred from blood to
tissues .
• Diffusion of molecules from High to Low conc
• O2 from the air to blood
• Facilitated diffusion: Uses carrier proteins but does
not use energy.
Active Transport and examples
• Carrier Mediated Transport: TAKES
energy to do this!!! Usually in the form of
ATP
• This can pump a molecule AGAINST the
gradient!!!
• Sodium/Potassium pump 3 Na out, 2K in
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Half your daily calories are used for this alone!!!!!! Why so important??
THIS PUMP:
1. Regulates cell volume
2. Provides secondary active transport via generating electricity to pump other
things..kidney function or Sodium Glucose transport
3. Heat production(thyroid stimulates na/k pump production..raising heat
4. Maintenance of membrane potential(Imp. In nerve function)
• Vesicular Transport: TAKES energy
• Endocytosis, exocytosis, phagocytosis,
pinocytosis
Most important Pumps
• Sodium-potassium pumps(Na-K): this pump burns
one ATP to push 3 Na+ out of cell and 2 K+ into
the cell
• Sodium-glucose transport protein(SGLT): binds
Na+ and glucose outside of cell. Uses ATP and
Na+ gradient to push glucose into cell
• ATP synthetase: As Na+ enters the cell ATP is
made from ADP and P+
Diffusion
• Diffusion: the process of particles, nutrients,
molecules, salts moving from high to low
concentration to achieve a balance
• Concentration Gradient: when the
concentration of a particle is higher in one
area then another
Osmolality
• Osmolality is the amount of solute (stuff) in
a solution.
• HYPO-tonic solution= has a LOW
concentration of solute compared to that
inside the cell High conc of water
• HYPER-tonic solution= has a HIGH
concentration of solute compared to that
inside the cell Low conc of water
• ISO-tonic solution= has equal conc of
water is same as the cell.
Movement of water
• Osmosis: the process of water moving from
low solute(High Water) to high solute
(Low Water)through a selectively
permeable membrane
• Osmotic Pressure: the force that stops
osmosis due to filtration.(the flow of water
across the membrane due to it’s own weight
= the flow of water due to osmosis
• http://www.mhhe.com