transport in cells (4) Flashcards
what is a plasma membrane?
a phospholipid bilayer embedded with proteins, carbohydrates and cholesterol.
What are hydrophobic molecules
Water hating (lipid loving)
What are hydrophilic molecules
Water loving (lipid hating)
What is the plasma membrane often referred as
Fluid mosaic model
What is the fluid mosaic model embedded with
Protein and cholesterol
Transport proteins…
cross the entire membrane and act as pathways for ions and larger polar molecules
Channel proteins
tunnel ions through the membrane
Carrier proteins
have to change shape to transport substances into the cell
What do cells need to function
nutrients and gases
Where do cells obtain nutrients and gases from
Extracellular fluid around them
what do cells need to remove
waste molecules and gases from the cytosol into the extracellular fluid
what is semi permeable
cell membrane
what does semi permeable mean
lets some things through and others not, determined by size, chemical nature and electric charge
what is diffusion
diffusion is the net movement of molecules from a region of higher concentration to lower
what does passive movements not require
energy
what is simple diffusion
small, non polar molecules (o2, co2), diffuse directly through the phospholipid layer. no energy required.
what is facilitated diffusion
when some substances cannot dissolve across the membrane due to size or charge. these substances move across via transport proteins
what is osmosis
the movement of water molecules across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.
what is active transport
the net movement of dissolved substances into or out of cells against a concentration gradient. enters via a transport protein. energy is required
what is bulk transport (endocytosis)
the transport of large particles into cell.
how does bulk transporting (endocytosis) work
part of the plasma membrane encloses the material to be transported and then pinches off to form a vesicle that moves into the cytosol
what is bulk transport (exocytosis)
transport of large substances OUT of a cell
Name all the types of transport.
Simple diffusion
Facilitated diffusion
Active transport
Osmosis
Endocytosis
Exocytosis
how does bulk transporting work (exocytosis)
a vesicle containing a substance travels to the membrane and fuses with it, realising the substance from the cell.
