Lesson 5: Cellular Transport Flashcards
the passage of materials into and out of cells is made possible by
cellular transport
factors that determine whether a substance can pass through a cell membrane or not
depending on their size and the functional groups present
allow for the regulation of the cell’s content and act as physical barriers for the cell
transport proteins
is the movement of substances across membranes without energy expenditure
passive transport
types of passive transport:
- diffusion
- osmosis
- facilitated diffusion
net movement of substances from an area of higher concentration, down the concentration gradient
diffusion
- is spontaneous and proceeds even without energy input
- some molecules may be moving against the gradient and some molecules may be moving down the gradient (motion is random)
is used to indicate the overall, eventual result of the movement
“net”
difussion
the diffusion of water molecules across a selectively permeable membrane
osmosis
process where solvent molecules like water move from a region of less concentrated solution to a region of more contentrated solution through a selectively permeable membrane
osmosis
Osmosis is the process where solvent molecules like water move from a region of less concentrated solution (_________) to a region of more contentrated solution (________) through a selectively permeable membrane
- hypotonic solution
- hypertonic solution
where the solute concentration is lower than that inside the cell
Hypotonic Solution
Water from the environment enters the cell, causing it to bulge or burst
where the solute concentration is higher than that inside of the cell
Hypertonic Solution
water leaves the cell, causing it to shrivel and die
in what environment do cells survive in?
isotonic
where solute concentration is equal to that inside of cell
what happens when cells that are surrounded by cell walls are placed in a hypotonic solution?
the inward movement of water builds up the turgor pressure of the cells and the cell then becomes very firm
without firmness or tirgidity, the plant wilts
what happends when cells that are surrounded by cell walls are placed in a hypertonic solution
water moves out, causing the plasma membrane to pull away from the cell wall
the cell becomes wilted or plasmolyzed
process where water moves out that causes the plasma membrane to pull away from the cell wall
plasmolysis
why is the addition of salt and sugar helpful against spoilage?
it increases the solute concentration / creates a hypertonic environment which is harmful for cells
refers to a situation in which plant cells are suspended in an isotonic solution
flaccid
refers to a condition in which plant cells are suspended in a hypertonic solution.
plasmolysed
refers to a condition in which plant cells are suspended in a hypotonic solution.
turgid
movement of solutes through protein channels down the concentration gradient, and without energy expenditure
facilitated diffusion
through this, water and certain hydrophilic solutes, cross the membrane
two types of transport proteins:
- channel proteins
- carrier proteins
- open or close as they respond to stimuli
- some open or close when a s pecific subtance, other than the subtance to be transported, binds to the channel
channel proteins
change in shape, triggered by the binding and release of a subtance it transports
carrier proteins
- the means of moving solutes across a membrane, up to the concentration gradient
- requires energy
active transport
the active transport requires the expenditure of energy through transport protein called
carrier proteins
what does the active transport utilized for energy?
adenosine triphosphate (ATP)
energy currency of the cell
this changes the shape of a transport protein, such that it enables the translocation of the solute attached to it across the membrane
when the terminal phosphate group of ATP transfers to the transport protein
what makes the movement of molecules in active transport different with the movement in passive transport?
- movement in passive transport is nondirectional
- whereas, the movement allowed for by active transport across membranes is unidirectional
if water and small solutes enter and leave the cell through passive and active diffusion, they how does large molecules such as protein and polysaccharides cross the membranes?
they cross the membranes in bulk through the processes of exocytosis and endocytosis
is the process of removing materials from the cell through the vesicles that fuse with the plasma membrane, subsequently releasing their contents outside the cell
exocytosis
- is common when a cell has to secrete substances for export
- e.g. secretion of digestive enzymes through the vesicle from the Golgi apparatus
is the reverse process of exocytosis wherein cells engulf materials
endocytosis
- is the most common form of endocytosis
- occurs when undissolved materials enters the cell
phagocytosis
“cellular eating”
e.g. white blood cells that engulf bacteria
occurs when dissolved substances enter the cell
pinocytosis
“cellular drinking”
e.g. human egg cell’s uptake of nutrients from its surroundings
- treatment given to patients with kidney failure
- it removes waste products from the blood when the kidney cannot do it
dialysis
