Cellular Transport Flashcards
What is the cytoskeleton made of
Microtubules
Microfilaments
Intermediate filaments
what are microtubules
large, hollow tube shape made of tubulin, made in centrosomes and can be broken down or reassambled
what do microtubules do
form spindles and hold organelles in place
they are the track for motor proteins
what are microfilaments
they are the thinnest strands made of 2 actin chains twisted into helixes
what do microfilaments form
the cell cortex
what is the cell cortex
a mesh of microfilaments at the cell membrane that gives animals their shape
what are intermediate filaments
they are medium sized and highly variable
add strength
mutations likely to pass on
what are centrosomes
regions of the cell where tubulin is stored and organized into microtubules
most animal centrosomes contain
centrioles
centrioles
9 triplets of microtubules fused together into a cylinder and helps organize microtubule formation
centrioles are lacked in
fungi and plants
motor proteins
activated by ATP
changes in shape result in motion
most common proteins are
myosins, dynins, kinesins, and actins
all varied
kinesins
walk along microtubules dragging cargo like vesicles and organelles
how do motor proteins move
ATP drops a phosphate off, which gives the molecule energy by breaking the phosphate bond. The motor proteins uses the energy to move
Dynins
walk along microtubules dragging cargo or bending cilia and flagella
what motor proteins push microtubules past each other
kinesin push spindles for mitosis
dynin push microtubules for cilia motion
why does myosin push microfilaments past each other
to move the cell cortex or to move contract muscles
the pushing of microtubules past each other is known as what
sliding microtubule hypothesis
prokaryotic cytoskeleton
no nucleus
poorly developed
some lack cytoskeleton
all eukaroyotes have nearly identical genes for
actin and tubulin so they are highly conserved
tight junctions
block things from moving through cracks between cells
adhering (desmosomes) junctions
stick together, anchor cell in place by joining it to its neighbor
gap junctions
communicating junctions, cytoplasmic bridges between cell allow cytosol and small molecules to flow between cells
plasmodesmata
cytoplasmic bridges in plants
eukaryotic
membrane bound organelle
has nucleus
eukaryotic cilia and flagella
used for motion of cells ex sperm unicellular organisms
to move substances ex cilia moves eggs down oviduct, mucus in lung tracts
homologous structures among eukaryotic
anchored by basil body
homologous
same inherited
analogous
same function, different structure, not inherited
basil body has nine triplets, but one of everything three falls short, why?
to leave space for micrtubules
prokaryotic flagella
no basal body not covered by cell membrane different internal structure different protein (flagellin) analogous to eukaryotic flagella
cell membrane made of
phospholipid bilayer
selectively permeable
cholesterol
membrane proteins
phospholipid bilayer
hydrophilic heads point out (phosphate)
hydrophobic tails in center (fatty acid)
capable of rapid lateral movements
amphipathic
both philic and phobic
how is the phospholipid bilayer held together
by hydrophobic interactions
what molecules can pass through the membrane phospholipids on their own
small or non polar molecules (lipids)
how do large molecules get through
very slowly (glucose) or via transport proteins
how do ions get through
very seldom go through by their self, need to gain or lose an electron
how do you have faster transportation
use proteins
difference between selective and semi permeable membrane
selective can choose and change over time
semi permeable you cant choose, just based on size and stays same
cholesterol
found in animals cells
maintains membrane fluidity
what does cholesterol do at high temps
retrains p lipid movement
what does cholesterol do at low temps
prevents close packing
integral proteins
stuck in cell membrane, some are transmembrane (inside and out, part sticking in and out )
peripheral proteins
not embedded, edges of cell membrane. can be held in place by cytoskeleton (inside) or ECM extracellular matrix (outside)
membrane enzymes
often grouped in teams (speeds up process)
active in metabolism (building and breaking things down)
bind to cytoplasmic substrates- reactants
attachment proteins
bind to ECM(holds cell in place)
bind to cytoskeleton (move cell membrane with cell cortex)
maintain cell shape and location
non covalent (flexible changeable)
recognition proteins and lipids
sorts cells in embryo immune system self recognition often glycoproteins/lipids variant ex A B O blood types
intercellular joining
gap junctions and adhering junctions
receptor proteins aid in
signal transduction
process of transduction
receptors bind to chemical messenger (cAMP hormones)
binding signal molecule changes protein shape
signals inside of cell by binding cytoplasmic protein
transport proteins
always integral transmembrane
channel proteins
carrier proteins
and are all specific
channel proteins
ex aquaporin
makes hollow tube in the middle and stuff goes through
some gated so chooses what gets in and out
carrier proteins
glucose transporter and protein pumps
transporter
passive goes with the flow
pumps
active against gradient concentration
two types of cellular transport
passive transport and active transport
passive transport
no energy needed
molecules flow from high concentration to low concentration
active transport
energy needed
molecules pumped from low concentrations to high
exo/endocytosis
three types of passive transport
diffusion
facilitated diffusion
osmosis
diffusion
any molecule, random motion
high to low, movement due to concentration gradient
facilitated diffusion
molecules too big/polar/charged
must go through transport protein by channel protein or carrier
osmosis
diffusion of water through membrane
what is the relationship between solutes and concentration gradient
solutes follow their own concentration gradient
ignores all others
tonicity
ability of surronding solution to make a specific cell gain or lose water
isotonic
no net movement same solute (iso)
hypotonic solution
water moves into cell
less solute in solution (hypo)
hypertonic
water moves out of cell
more solute in solution (hyper)
osmoregulation
control of solute and water concentrations inside a cell
contractile vacoules
aquaporin
diffusion rates affected by
concentration size size of molecule temperature electric gradient pressure gradient number of pores
how does concentration size effect diffusion rate
increase concentration increase rate of diffusion- more molecules, more molecules crashing, better chance getting in, steeper concentration gradient
how does size of molecule effect diffusion rate
smaller cell size faster rate of diffusion- less volume SA:V
smaller cell size greater SA:V ratio
how does temperature effect diffusion rate
increase temp increase rate of diffusion- molecules go faster
how does electric gradient effect diffusion rate
moving ions, change charge to make opposites attract
how does SA effect diffusion rate
greater SA faster rate of diffusion, more space to enter cell (hair root LSI)
how does number of pores effect diffusion rate
larger or more pores increases diffusion- larger target opening
what does bulk transport
endo/exocytosis
protein pumps
carrier proteins that require energy
pushes molecules into areas where they are in high concentration
pumps h+ ions
exocytosis
how cells secrete materials like hormones
exocytosis path
transport vesicle buds from golgi
vesicle goes to CM and fuses
contents spill into extracellular space
endocytosis
phagocytosis
pinocytosis
receptor mediated
helps concentrate rare molecules
phagocytosis
takes in food
pinocytosis
takes in water
receptor mediated
triggered by molecule binding to membrane receptor
