Goal 2 - Active Transport Notes
ACTIVE TRANSPORT VERSUS PASSIVE TRANSPORT - Goal 2
Passive Transport
PASSIVE TRANSPORT requires NO energy. Like rolling a ball down a hill.
Simple Diffusion
Some particles can pass through the plasma membrane by simple diffusion. The cell uses NO energy to move these particles.
Facilitated Diffusion
Transport proteins (located within the plasma membrane) help substances to move through the plama membrane.
Carrier proteins are another type of transport protein.
Passive Transport
PASSIVE TRANSPORT requires NO energy. Like rolling a ball down a hill.
Simple Diffusion
Some particles can pass through the plasma membrane by simple diffusion. The cell uses NO energy to move these particles.
- Diffusion is classified as passive transport.
Facilitated Diffusion
Transport proteins (located within the plasma membrane) help substances to move through the plama membrane.
- Passive transport of materials across the plasma membrane using the transport proteins is called facilitated diffusion.
- Some transport proteins called channel proteins form channels that allow specific molecules to flow through. The movement is with the concentration gradient, and requires NO energy input from the cell
Carrier proteins are another type of transport protein.
- Carrier proteins change shape to allow substances to pass through the plasma membrane.
- In facilitated diffusion by carrier proteins, the movement is with the concentration gradient and require NO energy input from the cell.
Active Transport
ACTIVE TRANSPORT - requires the USE of ENERGY. Like rolling a ball up hill.
In many cases, cells must move materials up their concentrated gradient, from and area of lower concentration to an area of higher concentration. Such movement of materials is known as ACTIVE TRANSPORT.
Unlike Passive Transport, Active Transport REQUIRES A CELL TO EXPEND ENERGY (ATP).
Cells often move molecules across the membrane AGAINST a Concentration Gradient.
Cell membrane pumps from an area of LOW Concentration to areas of HIGH Concentration.
The cell membrane can pump and move molecules AGAINST the Concentration Gradient this REQUIRES ENERGY.
Carrier Proteins - Role in Active Transport
WHEN ENERGY IS USED TO TRANSPORT MOLECULES ACROSS THE MEMBRANE, THE PROCESS IS CALLED Active Transport often involves CARRIER PROTEINS.
Active transport allows particle movement into and out of the cell against the concentration gradient
Active Transport - Example in Plants
In Plants, ACTIVE TRANSPORT enables roots to absorb nutrients from the soil.
In many cases, cells must move materials up their concentrated gradient, from and area of lower concentration to an area of higher concentration. Such movement of materials is known as ACTIVE TRANSPORT.
Unlike Passive Transport, Active Transport REQUIRES A CELL TO EXPEND ENERGY (ATP).
Cells often move molecules across the membrane AGAINST a Concentration Gradient.
Cell membrane pumps from an area of LOW Concentration to areas of HIGH Concentration.
The cell membrane can pump and move molecules AGAINST the Concentration Gradient this REQUIRES ENERGY.
Carrier Proteins - Role in Active Transport
WHEN ENERGY IS USED TO TRANSPORT MOLECULES ACROSS THE MEMBRANE, THE PROCESS IS CALLED Active Transport often involves CARRIER PROTEINS.
- The CARRIER PROTEINS act as PUMPS that USE ENERGY to move IONS and Molecules across the membrane.
- The Carrier Proteins that serve in Active Transport are often called CELL MEMBRANE PUMPS.
- ACTIVE TRANSPORT is especially IMPORTANT in MAINTAINING ION CONCENTRATION IN CELLS AND BETWEEN CELLS.
- Carrier proteins first binds with a particle of the substance to be transported.
- Carrier protein must be a similar shape that fits the molecule or ion that it is binding to.
- When the molecule binds with the carrier protein, chemical energy allows the cell to change the shape of the carrier protein so that the particle to be moved is released on the other side of the membrane (like an open door). Once particle is released the carrier protein returns to its original shape.
Active transport allows particle movement into and out of the cell against the concentration gradient
- ATP supplies the energy
Active Transport - Example in Plants
In Plants, ACTIVE TRANSPORT enables roots to absorb nutrients from the soil.
- Plant Nutrients are more concentrated inside the roots than in the surrounding soil.
- WITHOUT ACTIVE TRANSPORT, NUTRIENTS would DIFFUSE OUT OF THE ROOTS.
- Active Transport in the root cell membrane enables the plant to absorb the nutrients against the Concentration Gradient
Active Transport - Bulk Transport
BULK TRANSPORT
Take in or release large molecules from the cell. These molecules or particle are too large to pass directly through the plasma membrane.
Two process are involved in taking in or releasing large molecule from the cell - ENDOCYTOSIS AND EXOCYTOSIS
Some Molecules, such as COMPLEX PROTEINS, are too LARGE to cross the Cell Membrane.
These Substances cross the Membrane by BULK TRANSPORT.
Endocytosis
LARGE MOLECULES, FOOD, AND OTHER SUBSTANCES ARE engulfed and enclosed by a portion of the cell plasma membrane (PACKAGED IN MEMBRANE-BOUND SACS CALLED A VACUOLE) AND MOVED ACROSS THE MEMBRANE.
Exocytosis
EXOCYTOSIS IS THE OPPOSITE OR REVERSE OF ENDOCYTOSIS.
Endocytosis and Exocytosis
Take in or release large molecules from the cell. These molecules or particle are too large to pass directly through the plasma membrane.
Two process are involved in taking in or releasing large molecule from the cell - ENDOCYTOSIS AND EXOCYTOSIS
Some Molecules, such as COMPLEX PROTEINS, are too LARGE to cross the Cell Membrane.
These Substances cross the Membrane by BULK TRANSPORT.
Endocytosis
LARGE MOLECULES, FOOD, AND OTHER SUBSTANCES ARE engulfed and enclosed by a portion of the cell plasma membrane (PACKAGED IN MEMBRANE-BOUND SACS CALLED A VACUOLE) AND MOVED ACROSS THE MEMBRANE.
- During ENDOCYTOSIS the Cell Membrane folds into a POUCH that Encloses the Particles.
- The Pouch pinches off INSIDE the Cell to form a VACUOLE (membrane-wrapped bubbles).
- The VACUOLE can then fuse with other Organelles (LYSOSOMES) or Release its contents into the Cytoplasm.
Exocytosis
EXOCYTOSIS IS THE OPPOSITE OR REVERSE OF ENDOCYTOSIS.
- DURING EXOCYTOSIS, WASTE AND CELL PRODUCTS LEAVE THE CELL.
- MUCUS, AND WASTE PRODUCTS ARE MATERIALS SECRETED BY EXOCYTOSIS
Endocytosis and Exocytosis
- Both move masses of material
- Both require energy
- Endo - means within “moves material into the cell”
- Exo - means out “moves material out of the cell”