Cell Bio Flashcards
Membrane function
holds internal content of the cell separate from the outside and regulate what gets into and out of the cell.
Water, gases (O2, CO2), small noncharged or non-polar molecules pass through NA+, large molecules like sugar cannot
phospholipid bilayer
- two layers of phospholipids, flexible structure describes a fluid mosaic model
- cholesterol is an integral part of the cell membrane, is in the hydrophobic portion keeps the membrane flexible
Membrane proteins
associated with the membrane - some are external, some are on the inside, and some are transmembrane proteins (across)
function
1) acting as receptors
2) channels or pumps for ions and other material to cross the membrane
3) signaling across the membrane
Passive movements
diffusion
osmosis
diffusion
the tendency of molecules to spread from areas of high concentration to areas of low concentration in order to reach equal concentration throughout- the process is driven by the concentration gradient
Osmosis
movement of water across a cell membrane from high concentration to low areas
thing of salt
isotonic
equal salt concentration inside and outside of cells
hypotonic
salt concentrations outside the cell are less than those inside the cell,
water moves into the cell to reduce the internal salt concentration
the cell will swell and may eventually burst
Hypertonic
salt concentrations outside the cell are greater than those inside the cell.
water moves out of the cell to increase the internal salt concentration, the cell will shrink
active movement
requires cellular energy
Active transport
involves transmembrane protein acting as “pumps”- ATP is required - into the cell or “pumping out” materials such as ions to maintain unequal concentration such as K+ or Na+
Endocytosis
bringing something into the cell across the membrane
- Receptor-mediated endocytosis
- phagocytosis
- pinocytosis
receptor-mediated endocytosis
the molecule binds to a receptor on the surface of the cell- that triggers the receptors and the material bound to it to be brought in through the cell membrane to the inside of the cell in a vesicle
Phagocytosis
cell engulfs solid material (white blood cells ingesting a bacteria)- bring it in through the cell membrane and breaks it down
Pinocytosis
cell engulfs and brings in liquid material
exocytosis
moving something in vesicle from the inside of the cell to be released to the outside
Cytoplasm
the fluid or gel inside the cell (cytosol) and the various organelles
Ribosomes
structure and function
very small made up of 2 circular subunits-found free in the cytoplasm or attached to the round endoplasmic reticulum
the function is to make protein
Endoplasmic reticulum
structure and function
a ‘stack’ of folded interconnected membranes-start at the edge of the nuclear membrane
function- two type
rough: covered with ribosomes=make protein
smoot: make lipids