chapter 4: cells Flashcards
common features of cells
- maintain integrity and shape of a cell
- obtain nutrients and form chemical building blocks
- dispose of wastes
- SOME are capable of cell divison
plasma membrane
forms outer, limiting barrier separating internal contents from external environments
nucleus
- largest structure in cell; enclosed by a nuclear envelope
- contains genetic material DNA
cytoplasm
space contains all cellular contents between plasma membrane and nucleus
functions of the plasma membrane
1) physical barrier
2) selectively permeable boundary
3) communicator
4) electrochemical gradient (discussed with muscle and neurons)
passive process
movement of water or solutes from high to low concentration, energy is NOT used
diffusion
- movement down the concentration gradient (high to low concentration)
- does not require energy to get molecules across the plasma membrane
facilitated diffusion
transport protein required
channel-mediated diffusion
ion moves through channel
- movement of small ions across the plasma membrane through a protein channel
carrier-mediated diffusion
small polar molecule moved by carrier protein
- movement of polar molecules by binding to a carrier protein in the plasma membrane
- carrier protein changes shape and releases the molecule to the other side of the membrane
osmosis
- movement of water, not solutes
- energy is NOT used
- passive movement of water throughs electively permeable membrane
active processes
movement of solute up its concentration gradient (low to high concentration)
- requires energy (ATP)
active transport
- primary active transport
energy source from ATP
- sodium / potassium pump
secondary active transport
energy source from movement of another substance
secondary active transport
- symport
two substances moved in the same direction
antiport
two substances moved in opposite directions
vesicular transport
- aka bulk transport
involves energy input to transport large substances across the plasma membrane by a vesicle
vesicular transport
- exocytosis
large substances secreted from cell
vesicular transport
- endocytosis
cellular uptake of large substances from external enviornment
receptor
cell surface protein located in plasma membrane
ligand
molecule secreted from another cell that binds to receptor
ligand gated ion channels
if ligand can bind the to the receptor, then the receptor relays information to inside of the cell OR ligand can cause an ion channel to open or allow ions to flow through cells
purpose of cell signaling
important for controlling growth, reproduction, and other cellular processes
DNA
genetic code
