4.2 cell transport mechanisms Flashcards
what is the structure of the cell surface membrane?
- parcially permeable membrane
- phospholipids with protein molecules between them
what are the different types of proteins in the cell surface membrane?
- transport proteins
- receptor proteins
- enzymes
- structural proteins
- recognition proteins
what is the function of the cell membrane?
to control the movement of substancesin and out of the cell
why do membranes need to be fluid?
- white blood cells need to engulf
- red blood cells need to be flexible to fit in capiliaries
what are membranes made of?
phospholipid bilayer (hydrophilic head and hydrophobic tail)
which molecules can diffuse through the bilayer?
fat soluble molecules
which molecules require proteins to pass through the membrane?
polar molecules
what are the three types of passive transport in cells?
- diffusion
- facilitated diffusion
- osmosis
what is diffusion?
the passive movement of small, non-polar, lipid-soluble molecules such as carbon dioxide and oxygen from an area of high concentration to low across the cell membrane
what can speed up diffusion?
- surface area increases
- diffusion distance decreases
- diffusion gradient becomes more steep
what is facilitated diffusion?
diffusion of polar, charged and water-soluble molecules that takes place through carrier proteins or protein channels in the cell membrane
what is osmosis?
the movement of water molecules from an area of high water potential to low water potential through a parcially permeable membrane
what are the three types of active transport in cells?
- endocytosis
- exocytosis
- active transport
what is endocytosis?
the movement of large molecules into cells through vesicle formation
what is exocytosis?
the movement of large molecules out of cells through vesicle formation
