2.1.7 - Active Transport Flashcards
Define Active Transport (AT)?
Movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration.
What Does AT Require?
(2 Points)
~ Energy in form of ATP from respiration to move substances against their concentration gradient, which is why it is an active process.
~ Carrier proteins.
What Type Of Process Is AT?
Active.
Why Is Energy Required & How?
(3 Points)
~ To change the shape of the carrier proteins.
~ Provided by ATP produced during respiration.
~ ATP is hydrolysed to release energy.
What Is Hydrolysis?
Breaking down of large molecules into smaller ones by the addition of water molecules.
What Are Examples Of AT?
(4 Points)
~ Reabsorption of useful molecules and ions into the blood after filtration into the kidney tubules.
~ Absorption of some products of digestion from the digestive tract into the blood.
~ Loading sugar from the photosynthesising cells of leaves into the phloem tissue for transport around the plant.
~ Loading inorganic ions from the soil into root hair cells.
What Is Endocytosis?
(6 Points)
~ Transport large particles.
~ Active process and requires a source of energy.
Steps Of Endocytosis:
~ Cell surrounds a substance with a section of the cell surface membrane.
~ The membrane engulfs the substance and pinches off inside the cell to form a temporary vacuole with the ingested substance contained inside.
~ Some molecules such as proteins, lipids and carbohydrates are too large to travel via membrane proteins.
~ E.g. Phagocytosis.
What Is Exocytosis?
(4 Points)
~ Active process and requires a source of energy.
~ Some substances produced by the cell need to be secreted such as hormones, enzymes and lipids.
Steps Of Exocytosis:
~ Vesicles containing the substance pinch off from sacs of the Golgi apparatus.
~ These vesicles are moved towards the cell surface and fuse with the cell surface membrane to be released outside the cell.
