Active Transport

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  • Created by: zoolouise
  • Created on: 20-04-16 11:34
What is the definition of active transport?
The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier proteins.
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What does active transport allow and what does it use?
It allows cells to exchange molecules against a concentration gradient, metabolic energy in the form of ATP is required for this.
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What happens once the molecules are inside?
Once inside, the molecules are prevented from leaking back out by the barrier of the cell surface membranes bilayer. Different environment maintained on either side of the membrane.
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How is active transport different from passive forms of transport?
Metabolic energy (ATP) is needed. Materials moved against a concentration gradient. Carrier protein molecules are involved and act as a 'pump'. Process is very selective, specific substances are transported.
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How does active transport use ATP?
Uses ATP directly to move molecules. Uses a concentration gradient that's already been set up by direct active transport, also known as co-transport.
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What are the steps (1-2) of direct active transport of a single molecule/ion?
Carrier proteins span the cell-surface membrane, accepting molecules/ions to be transported on one side of it. Molecule/ion binds to receptors on the channels of the carrier proteins.
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What are the steps (3-4) of direct active transport of a single molecule?
On the inside of the cell, ATP binds to the protein causing it to split into ADP and a phosphate molecule. The protein molecule changes shape, opens to the opposite side of the membrane. Molecules ions are then released to other side of the membrane.
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What are the steps (5-6) or direct active transport of a single molecule or ion?
The phosphate molecule is released from the protein and recombines with ADP to form ATP. This causes the protein to revert to its original shape, ready for the process to be repeated.
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What can happen in active transport?
More than one molecule or ion can be moved at the same time, either in the same or different direction. e.g. sodium-potassium pump
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What happens in active transport in the case of sodium-potassium pump?
Sodium ions are actively removed from the cell while potassium ions are actively taken in from the surroundings.
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What affects active transport?
Anything which affects the respiratory process will affect active transport as the process requires ATP.
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What are the processes that involve active transport?
Muscle contraction, Protein Synthesis, Nerve impulse transmission, Absorption of mineral salts by plant roots
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What is endocytosis?
The cell surrounds the material with its cell membrane and then brings the material into the cytoplasm enclosed in a vesicle.
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What is phagocytosis?
How a cell obtains solid materials that are too large to be taken in via diffusion/active transport. Lysosome fuses with vesicle and enzymes in the vesicle digest the solid material. Products of digestion process then absorbed into the cytoplasm.
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What is pinocytosis?
How cells take in liquids, the process is the same as for phagocytosis but the vesicles used are much smaller.
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What is exocytosis?
How a cell can transport subtances through the cytoplasm in a vesicle and then release them to the outside of the cell. Digestive enzymes are often secreted in this way.
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Card 2

Front

What does active transport allow and what does it use?

Back

It allows cells to exchange molecules against a concentration gradient, metabolic energy in the form of ATP is required for this.

Card 3

Front

What happens once the molecules are inside?

Back

Preview of the front of card 3

Card 4

Front

How is active transport different from passive forms of transport?

Back

Preview of the front of card 4

Card 5

Front

How does active transport use ATP?

Back

Preview of the front of card 5
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