Download Transport - Valhalla High School

Transport
• The movement of
molecules and ions
across a membrane
Molecules in motion
• At all times molecules and ions are
moving into and out of your cells.
• The nutrients and oxygen your cells
need for respiration move in, and the
waste products move out.
• This activity is regulated by the cell
membrane.
Transport
• As we learned earlier, transport (the intake
and distribution of materials throughout an
organism) is one of the life processes.
• All molecules are not transported the same.
• Some types of transport require energy and
others do not.
• Sometimes molecules need a little help
getting from one side of the cell membrane to
the other.
Types of transport
I. Passive transport
II. Active transport
III. Endocytosis (Phagocytosis and
Pinocytosis)
IV. Cyclosis
Passive transport
• In passive transport there are two things that
you must remember.
1. There is no energy required.
2. Molecules move from areas of high concentration
to low concentration.
– Small molecules easily pass through the cell
membrane while larger ones need help.
– With ions, the charge of the particles can also
determine if they can diffuse across a cell
membrane.
Simple Diffusion
• Small molecules, such as dissolved
oxygen, carbon dioxide and glucose
pass through the cell membrane.
• They always move with the
concentration gradient, from high to low.
• No energy is required.
Facilitated diffusion
• Sometimes molecules are too big to pass
through the cell membrane on their own.
• These larger molecules require the help of
carrier proteins. Carrier or channel forming
proteins are embedded in the cell membrane.
• As with simple diffusion, no energy is
required, and molecules and ions move with
the concentration gradient.
Osmosis
• Osmosis refers to the passive transport of
water molecules across a cell membrane.
• As with the other times of passive transport
the water molecules move from high
concentration to low concentration.
• No energy is required for Osmosis.
Diffusion summation
• No energy
• Molecules move with the gradient
• Continues until equilibrium is reached.
This means that the concentration of
molecules are the same on both sides
of the membrane.
Passive transport video
• http://www.youtube.com/watch?v=JShw
XBWGMyY
Active transport
• Active transport is fundamentally
different from passive transport.
• In active transport, molecules move
against the concentration gradient,
which means they move from areas of
low concentration to high concentration.
• It also requires energy.
Endocytosis
• Endocytosis simply means the ingestion of solids or
liquids into a cell.
• Phagocytosis is the process by which solids are
taken into a cell. An amoeba eats paramecium by
the process of phagocytosis.
• Pinocytosis is the process by which liquids are taken
into a cell.
• Both phagocytosis and pinocytosis lead to the
production of vacuoles.
• The reverse process, of materials leaving a cell is
called exocytosis.
Passive v. active transport
• http://www.youtube.com/watch?v=1ZFq
OvxXg9M&feature=related
Cyclosis
• Cyclosis is the swirling motion of the
cytoplasm that helps to distribute
materials throughout a cell.
• Cyclosis does not directly require any
energy. The normal motion of the cell or
organism helps to create this motion.