U1L9: Cell Transport Flashcards
What is diffusion?
the tendency for molecules to spread out into available space. Molecules diffuse passively down a concentration gradient (particles move from an area of high concentration to an area of low concentration until the concentrations are equal
What is diffusion AKA?
Diffusion is also called passive transport because no energy is used during this process
What is Facilitated Diffusion
the use of a transport protein to bring a polar molecule (e.g. glucose) through a membrane. Facilitated diffusion is also passive as it uses a concentration gradient (no energy) to transport.
Wha is osmosis?
Osmosis refers to the passive transport of water (i.e. the diffusion of water from an area of high concentration to an area of low concentration)
What is a Isotonic Solution
the concentration of water is the same outside the cell as it is inside the cell. Therefore, water moves in and out of the cell at an equal rate.
What is a Hypertonic Solution
the concentration of water is higher in the cell than it is outside the cell. Therefore, water has the tendency to move out of the cell causing the cell to shrivel and become flaccid.
What is a Hypotonic Solution
the concentration of water is higher outside the cell than it is inside the cell. Therefore, water has the tendency to move into the cell causing it to become turgid (very firm).
What is the main function of Active Transport
To pump a molecule across a membrane against its gradient (e.g. from low concentration to high concentration). This requires ATP energy. A cell needs to use active transport to maintain internal cellular concentrations of various ions
What is an example of Active Transport?
For example: compared to its surroundings, an animal cell has a much higher concentration of K+ ions and a much lower concentration of Na+ ions and an Na-K pump (protein) uses active transport to pump Na+ out of the cell and K+ into the cell
What is Exocytosis
a cell secretes macromolecules
What is Endocytosis
a cell takes in macromolecules
What are the 3 types of endocytosis?
There are three types of endocytosis: phagocyotsis, pinocyotosis, and receptor-mediated endocytosis
What is Phagocytosis
“cell eating”. A cell engulfs large particles by wrapping pseudopods around it and packaging it with a membrane bound sac (e.g. vesicle)
What is Pinocytosis
“cell drinking”. A cell “gulps” droplets of extracellular fluid into tiny vesicles
What is receptor-Mediated Endocytosis
A cell targets very specific molecules with the protein receptors on the cell membrane.
