Biology Test 2
microfilaments
(actin filaments) support the cell's shape and are involved in motility
microtubules
(made of tubulin) shape the cell and act as tracks for motor protein
concentration gradient
A difference in the concentration of a substance across a distance.
integrins
ECM attaches through connecting proteins that binds to membrane proteins called
hypertonic... greater
In osmosis, water always moves toward the ____ solution: that is, toward the solution with the ____ solute concentration.
his stomach cells would be surrounded by a really high concentration. it would cause his stomach to swell.
Seawater is hypertonic in comparison to body tissues. explain what would happen to his stomach cells if a shipwrecked sailor drank seawater.
endocytosis
a nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. these molecules probably enter the cells lining the baby's digestive tract via
the cell will shrivel because of osmosis
a plant cell is placed in a solution whose solute concentration is twice as great as the concentration of the cell cytoplasm. the cell membrane is selectively permeable, allowing water but not the solutes to pass through. what will happen to the cell?
exocytosis
a white blood cell is capable of producing and releasing thousands of antibody molecules every second. antibodies are large, complex protein molecules. how would you expect them to leave the cell?
gap junctions
are channels that allow molecules to flow between cells
vacuole
are membranous sacs that are found in a variety of cells and possess an assortment of functions
chloroplasts
are the photosynthesizing organelles of plants
selectively permeability
because membranes allow some substances to cross or be transported more easily than others, they exhibit
cytoskeleton
cells contain a network of protein fibers, called this, that functions in cell structural support and motility
mitochondria
cellular respiration is accomplished in this of eukaryotic cells
dynein arms
cilia and flagella move by bending motor proteins called
a plant would gain water in a hypotonic solution & lose water in a hypertonic solution. a animal cell would gain water by hypertonic solution & lose water by hypotonic solution.
describe the circumstances under which plant and animal cells gain and lose water by osmosis. which of the following is the least serious problem: water gain by a plant cell, water loss by a plant cell, water gain by an animal cell, or water loss by an animal cell? why?
anything that is large or polar molecules. there are transport protein that allow them to go through.
describe the kinds of molecules that cannot easily diffuse through cell membranes. how do proteins facilitate diffusion of these substances?
tonicity
describes the ability of a solution to cause a cell to gain or lose water
passive transport
diffusion across a cell membrane does not require energy
osmosis
diffusion of water across a selectively permeable membrane is called
intermembrane space
encloses the mitochondrial matrix where materials necessary for ATP generation are found
anchoring junctions
fasten cell's together into sheets
hypotonic
indicates a higher concentration of solute inside the cell
isotonic
indicates that the concentration of a solute is the same on both sides
hypertonic
indicates that the concentration of solute is higher outside the cell
extracellualr matrix (ECM)
is composed of strong fibers of collagen, which holds cells together and protects the plasma membrane
phagocytosis
is engulfment of a particle by wrapping cell membrane around it, forming a vacuole
photosynthesis
is the conversation of light energy to chemical energy of sugar molecules
pinocytosis
is the same thing except that fluids are taken into small vesicles
exocytosis
is used to export bulky molecules, such as proteins or polysaccharides
endocytosis
is used to import substances useful to the livelihood of the cell
receptor-mediated endocytosis
is where receptors in a receptor-coated pit interact with a specific protein, initiating formation of a vesicle
osmotegulation
many organisms are able to maintain water balance within their cells by a process called
hydrophilic heads... hydrophobic tails
phospholipid molecules in a membrane are arranged with their ___________ on the exterior and their ______________ on their interior.
plasmodestmata
plant cells have cell junctions called this that serve in communication between cells
cell wall
plant, but not animal cells, have a rigid
tight junctions
prevent leakage of extracellular fluid across a layer of epithelial cells
flagellum
propels a cell by an undulating, whiplike motion
less than... equal to
red blood cells shrivel when placed in a 10% sucrose solution. when first placed in the solution, the solute concentration of the cells is ______________ the concentration of the sucrose solution. after the cells shrivel, their solute concentration is ___________ the concentration of the sucrose solution.
intermediate filaments
reinforce cell shape and anchor organelles
endosymbiosis
the hypothesis of this proposes that mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells
diffusion
the movement of molecules from an area of higher concentraction to an area of lower concentraction is called
facilitated diffusion
these proteins assist in this, a type of passive transport that does not require energy
aquaporins
they require the help of specific transport proteins called
osmosis
water moves across membranes in response to solute concentration inside and outside of the cell by a process called
receptor-mediated endocytosis
which of the following enables a cell to pick up and concentrate a specific kind of molecule?
AT requires energy from ATP, and FD does not
which of the following is a difference between active transport (AT) and facilitated diffusion (FD)?
a large polar molecule
which of the following would be least likely to diffuse through a cell membrane without the help of a transport protein?
cilia
work more like the oars of a crew boat
