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30 Cards in this Set

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  • Back
What two characteristics do all cells have in common?
All cells have plasma membrane which controls the passage of water/gas/molecules in and out. All cells have hereditary info that they pass on to daughter cells.
Describe some characteristics of prokaryotes
"before nucleus"
archaea and bacteria
high level of diversity confined to a cell
Describe some characteristics of eukaryotes
"true nucleus"
plants/animals/fungi/protitsts etc
What is the outer living limit of a cell? What is its function?
The outer living limit of a cell is the plasma membrane. The plasma membrane holds the components of a cell together and serva as a barrier or "gate keeper" for things that move in and out of the cell
Why are the phospholipid heads of the plasma membrane always pointed towards the cytosol and the extracellular fluid, whereas the tails are always oriented towards the middle of the membrane?
the phospholipid heads are always pointed towards the outer limits becaues the phospholipid heads are hydrophilic and polar (like water).
The 2 fatty acid chains only point inwards becaues they are hydrophobic/nonpolar (not like water)
What are the 4 main components of the plasma membrane?
phospholipid bilayer, cholesterol, proteins, glycoalyx
Describe the phospholipid bilayer
it gives membrane fluid nature and lets hydrophobic molecules pass through
Describe cholesterol of the plasma membrane
"patching" material--keeps small molecules from passing through the membrane
keeps optimal fluidity
Describe the proteins of the plasma membrane
2 kinds- integral and peripheral. integral-bound to the hydrophobic interior, peripheral-on surface of membrane and usually attached to integral proteins.
support structures, signaling antennas, identification markers, cellular passageways
Describe the glycoalyx of the plasma membrane
simple carbohydrate chains. formal layer on outside of membrane that attach to lipids and proteins.
they are protein binding sites that assist in cellular lubrication/adhesion molecules
what is the fluid mosaic model and why is it important to biological organisms?
the fluid mosaic model is a conceptualization of the plasma membrane as a fluid, phospholipid bilayer that has within it a mosaic of stationary and mobile proteins.
Define diffusion
movement of molecules from high concentration to low
ex: dye in water
Define osmosis
movement of water across the semi-perm membrane from low solute concentration to high solute concentration
Define semi-permeable membrane
some particles can pass through, others cannot. can control the extent to which certain substances pass through
What can and cant pass through the semi-permeable membrane?
CAN: nonpolars (ex: lipids), small polars (CO2, H20).
CANNOT: ions/charged molecules (ex: salts dissolved into H20), large polars (glucose), macromolecules
Define hypotonic
lower concentration of solutes than the cytoplasm of a cell
water flows into cell, causing swelling and expansion of a cell
in extreme conditions, membrane cant stand osmotic pressure of water inside and explodes
Define isotonic
equal solute concentration in and out of cell
water flows equally in and out
cell size stays the same
Define hypertonic
a cell environment that has a higher concentration of solutes than in cytoplasm
water will flow out of cell
if enough water is removed in this way, cytoplasm can become so concentrated that the cell can have difficulty functioning
how do plant cells prevent cell explosion in hypotonic environments?
the cell wall
define simple diffusion
a form of passive transport. particles simply pass through the membrane
define facilitated diffusion
transmembrane (integral) proteins form a channel through the cell membrane. channel can be opened or closed and doesnt require energy (ATP)
what kind of particles can pass through with simple diffusion?
limited to low molecular weight and uncharged molecules. gasses and small organic chemicals can pass through the mem with only simple diffusion.
O2, CO2, alcohol, anesthetics, pesticides, h2o
what kind of particles can pass through with facilitated diffusion?
glucose, ions, h2o
define active transport
transmembrane proteins form channel through membrane but require energy.
which form of transport moves particles from more to less concentration?
facilitated/simple diffusion
which form of transport moves from less to more concentration?
active transport
define exocytosis
move out of cell thru transport vesicle which moves in and out of the plasma membrane
what are the two parts of endocytosis
pinocytosis and phagocytosis
define pinocytosis
receptors on cell membrane grab molecules and make transport vesicles through invagination
define phagocytosis
no receptor needed--bacterium or food particles